JP3034717B2 - Power monitoring and control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to individual monitoring of various types of distribution equipment such as transformers, circuit breakers, etc., as well as transducers such as transformers and integrating wattmeters, instrumentation equipment and electromagnetic switches. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution equipment monitoring and control device that can easily configure a distribution equipment monitoring and control system in which control information is networked. .

[0002]

2. Description of the Related Art In general, a system using a control device of this type generally has a plurality of terminal control devices for performing specific monitoring and control corresponding to power distribution equipment, a central monitoring and control device for centrally monitoring them, and a transmission system for interconnecting them. Generally, it is composed of a line or the like.

In such a general system, when applied to a power receiving and distribution system, it is necessary to control a plurality of terminal control devices in a hierarchical manner, and complicated control is required as a power distribution system.

A device of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-27.
No. 4630 is an example of a distribution equipment monitoring and control device. In this example, there is shown a system including a large number of terminal control devices that perform corresponding control in response to a control command, a control command device that comprehensively monitors these, and issues a control command, and a signal transmission line.

[0005] In a conventional distribution equipment monitoring and control apparatus, an average value measurement or a peak value measurement is generally used as a voltage and current measurement method.

[0006]

The above-described conventional power distribution equipment monitoring and control apparatus has the following problems. (1) When the voltage and current are measured by an average value measurement method, the measurement accuracy may be inaccurate due to waveform distortion generated by an electronic device such as an inverter.

(2) The transmission protocol between the terminal control unit and the central monitoring and control unit is dedicated, and it is difficult to utilize the existing assets of the user such as a personal computer. Was needed.

(3) In a device having a function of selecting and displaying monitoring information, a key operation for reading out desired information is complicated.

(4) Since a transmission signal is superimposed on a power supply line and transmitted, an electric wire having a large sectional area (for example, 1.2 mm ² ) is required so as not to cause a voltage drop, and the transmission distance is also 5
It was limited to about 00m and the wiring work was troublesome.
Also, a dedicated transmission power supply was required.

(5) At the time of a connection test or operation check, the central monitoring and control device cannot be connected to an arbitrary part in the network, so that it takes a long time to start up after installation, and
Maintenance is not easy.

(6) The verification of the zero-phase current with the circuit current and the current cannot be performed by the terminal device alone.

(7) When the terminal control device needs to be replaced,
Transmission lines and other wiring had to be removed, and the transmission function of the system was temporarily lost.

[0013] (8) without the ability to measure a utilization against the rated capacity of the transformer power saving was incomplete.

[0014] It is an object of the present invention to display on a power supply monitoring and control device the usage rate for a rated capacity of a transformer or to provide a central monitoring system.
It is an object of the present invention to provide a power supply monitoring and control system capable of transmitting power to a control device and replacing the transformer with a transformer having an appropriate capacity in accordance with the power, thereby saving power and extending the life of the distribution system.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a power supply monitoring and control system comprising: an input unit for inputting voltage and current information of a distribution system including a transformer; and an input unit connected to the input unit. An analog interface circuit for performing effective value conversion and digital conversion of an analog signal, a central processing unit connected to the analog interface circuit, and an operation unit connected to the central processing unit for selecting information to be displayed. a display unit for displaying the information selected by the operation unit is connected to the central processing unit, the central Starring
Having a transmission interface unit connected to the arithmetic processing unit
Connected to the transmission interface
The information selected by the operation unit via the transmission line
Digital transmission central monitoring and control unit
The equipment is configured with a pre-configured transformer connected to the distribution grid.
Ratio of the actually used power to the rated power capacity
Display unit configured to store the usage rate calculated from the
Is configured to display the usage rate by selecting the operation unit,
The central monitoring and control unit becomes a power monitoring and control unit by command
That the stored usage rate is configured to be readable.
It is characterized by the following. Further, the present invention provides the above configuration
A power supply monitoring and control system having
There is a repeater interposed between the
The repeater has a pair of transmission line connection terminals and a pair of
, A pair of polarity detection circuits, and one of transmission signals.
A frequency divider that creates the time for the word length,
A reset circuit that initializes the polarity detection circuit after the elapse.
For example, one of the driver / receiver pair is used for the transmission of the pair.
A pair of drivers connected to one of the wire connection terminals
/ The other side of the receiver is connected to the other side of the pair of transmission line connection terminals
And a pair of polarity detection circuits is a pair of driver / receiver.
Shaping and amplification of transmission waveforms by connecting them in anti-parallel between
Is performed.

[0016]

The input section takes in information on the voltage and current of the distribution system. The analog interface circuit is connected to the input section and performs effective value conversion and digital conversion of an analog signal. The central processing unit performs overall control of the power supply monitoring and control unit and performs calculations based on voltage and current information such as calculation of power. The operation unit selects information to be displayed from information processed by the central processing unit. The display unit displays information selected by the operation unit. The transmission interface unit transmits information on the power distribution system based on the voltage and current information output from the central processing unit to a remote central monitoring and control unit.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

A power supply monitoring and control device including a power distribution device according to one embodiment of the present invention has the following configuration. (1) An effective value measurement method such as voltage and current was used, and a circuit was used to improve measurement accuracy. (2) A basic transmission control procedure (hereinafter referred to as a basic procedure) standardized by JIS (X5002) is used as a transmission protocol with the central monitoring and control apparatus. (3) For selecting monitoring information, the information is displayed by key input corresponding to the information item. The details of the information items are displayed cyclically by repeatedly inputting the same key. Each key can be used as another definition by mode switching. (4) A twisted pair cable having a small nominal cross-sectional area (0.2 mm ² or more) can be used by adopting an RS-485 transmission system standardized by EIA (Electronic Industries Association of America) as a transmission line. Do not require a dedicated transmission power supply individually. (5) The central monitoring and control device can be connected to any part of the network. (6) Verification of the zero-phase current, voltage, and current can be performed in the same terminal control device. (7) The terminal is detachable. (8) The usage rate can be measured. In this embodiment, the power supply monitoring and control device measures the measured information as an effective value and transmits the corresponding information to a central monitoring and control device composed of a personal computer or the like using a standard transmission protocol.

Data is transmitted through a twisted pair cable having a small cross section as a transmission line, and the transmission distance is extended.

A key input corresponding to an information item is used to select the monitoring control information, and further detailed information is cyclically displayed by repeatedly pressing the key.

When the mode is switched, the above keys function as other function keys. A plurality of pieces of information in the power supply monitoring and control device are operated in a complex manner, and new information is generated by combining information.

Referring to FIG. 1, a system according to an embodiment of the present invention will be described. FIG. 1 (a) is a conventional system that does not use a monitoring device, which is a transformer 3, a meter 3 connected to a zero-phase current transformer (hereinafter referred to as ZCT) 4 constituting a power distribution board 1 ', and a transformer ( A protection relay 6 connected to a PT 5 and an integrated wattmeter 8 connected to a current transformer 7 (hereinafter referred to as CT) 7.
, And the circuit breaker 9 ′ have no data transmission function, display individual monitoring control information individually, and do not have a device for supervising and controlling the whole. For this reason, it was necessary to go to the installation site regularly for inspection of the distribution board.

FIG. 1B shows a system according to this embodiment. In the present embodiment, reference numeral 8 denotes a pulse integrating watt-hour meter capable of outputting the used electric energy in pulses.
The circuit breaker 9 is capable of outputting a contact signal 11 indicating an internal state, has a data transmission function, and outputs those data to the power supply monitoring and control unit 10 .
The oil temperature, the ambient temperature, and the like of the transformer 2 are measured by a sensor (hereinafter referred to as a resistance temperature detector) 14, and these temperature data are output to the power supply monitoring and control unit 10 via a signal line. Each of ZCT4, PT5, and CT7 detects a leakage current, a voltage, and a current of a circuit on the secondary side of the transformer 2, and outputs them to the power supply monitoring and control unit 10 through signal lines.

The power supply monitoring and control unit 10 includes ZCT4, P
Analog signal information of T5 and CT7, a contact signal 11 indicating the internal state of the circuit breaker 9, a digital signal such as a pulse signal of the integrating wattmeter 8, and a resistance bulb 14
And the like, to monitor and control analog signals such as the signals in the system, display information in the power distribution board 1 and transmit data to the remote master station 12 via the transmission line 13. The transmission line 13 is connected to a plurality of units including a power monitoring and control unit of another power distribution board, and the master station 12 monitors and controls the status of these units.

In the system (b) according to the present embodiment,
(B) Labor saving in administrative work by centralizing monitoring and control;
(B) Energy saving by grasping and controlling the power demand and power factor of each switchboard, and (c) minimizing the size and range of accidents and preventing accidents by detecting abnormalities early by constantly monitoring the equipment and measuring preventive safety.

FIG. 2 is a block diagram of the power supply monitoring and control unit 10. Central processing unit (hereinafter referred to as CPU) that controls various analog inputs, digital inputs, and other controls
The analog interface circuit 24 is connected to a signal line from the CT7, a signal line from the ZCT4, and a signal line from the PT5. The signal of CT7 is transformed once again by a secondary current transformer (hereinafter referred to as internal CT) 22 so that it can be taken into an analog interface circuit 24, and the output of PT5 is outputted by a secondary transformer (hereinafter referred to as internal PT) 23. It is transformed again so that it can be taken into the analog interface circuit 24. ZC
The signal from T4 is directly sent to the analog interface circuit 2
It is taken in by 4.

The signal from the resistance temperature detector 14 is transmitted via a temperature measurement interface 25 for converting the signal from the sensor into a voltage, and the signal from the pulse integrated watt-hour meter 8 is transmitted via a pulse interface 26 for counting the pulse output. Each is output to a bus 34 connected to the CPU 28.

Reference numeral 15 denotes a power supply line for supplying power to the power supply monitoring and control unit 10, and reference numeral 27 denotes a power supply section for converting the power supplied from the control power supply 15 to a voltage used inside the power supply monitoring and control unit 10.

Reference numeral 13 denotes a transmission line connectable between the power supply monitoring control units 10 and between the master stations. Reference numeral 16 denotes a conversion of a transmission signal from the CPU 28 to the transmission line 13 into the above-described RS-485 transmission system, or This is a transmission interface for converting a signal transmitted from the RS-485 transmission system into a signal that can be determined by the CPU. 17 is various analog values,
Digital value and error item, presence or absence of digital input,
A display unit for displaying the presence / absence of a transmission / reception signal to the transmission line 13, the presence / absence of a digital output, etc. 29 is a driver for driving the display unit 17, 18 is a display selection of analog and digital input values and setting of monitoring values, PT ratio, An operation unit 30 that enables setting of a CT ratio and the like, etc.
Is the key buffer to tell.

Reference numeral 31 denotes a storage unit for storing data and programs, which is constituted by a memory element. This memory element 31 is an EEPROM in this embodiment. Reference numeral 19 denotes an alarm contact that operates under the control of the CPU 28 when the analog input value exceeds a monitoring value, 32 denotes a driver that receives an output signal from the CPU 28 and drives the alarm contact, and 20 denotes a power monitoring and control unit 10. A device address setting unit to be set. Reference numeral 21 denotes a transmission speed setting unit that makes the transmission speed to the transmission line 13 variable, 33 denotes a device address setting unit 20, a buffer for transmitting the setting contents of the transmission speed setting unit 21 to the CPU 28, and 34 denotes a CPU and each unit. It is an internal bus that connects

The power supply unit 2 is provided inside the power supply monitoring control unit 10.
7 eliminates the need for an external power supply, and supplies power to the power supply unit 27 at AC 85 V to 260 V or D
By diversifying with C110V, power can be supplied from various power supplies wired to sub-substations and the like. Therefore, a step-up / step-down power supply is not required, and troublesome work such as wiring work is also eliminated.

The transmission interface has the EIA described above.
By adopting the RS-485 system according to the standard,
Even a transmission line with a small cross-sectional area of 0.2 mm ²
It is possible to transmit at 8 kbps. Since the diameter of the transmission line can be small in spite of the high-speed transmission, wiring between the power supply monitoring and control units 10 and between the master station 12 can be performed easily and at low cost.

Next, an example of system connection is shown in FIG.

Reference numerals 10 and 12 denote the above-described power supply monitoring and control unit and the master station. The power supply monitoring and control unit 10 adopts the above-described RS-485 system specified by EIA as a communication specification for performing long-distance transmission. I have.

On the other hand, in the case of a general personal computer or the like, the master station 12 has the above-mentioned EIA standard RS-232.
Since a C-type interface is provided as standard, a converter 35 for converting an electric level is provided during this time.

In the RS-485 system, since the maximum transmission distance is 1.2 km, a repeater (amplifier) 36 for performing long-distance transmission is provided.

The devices thus configured are connected by a transmission line 13 in a bus system.

Here, the repeater 36 has a feature that it can be connected to any position as shown in FIG. (The reason will be described in detail with reference to FIG. 6.) According to such a repeater connection method, there is an effect that devices can be efficiently distributed in all directions since branching can be performed from the middle.

Next, FIG. 4 is an external view of the above-mentioned converter 35, and shows how the converter 35 is connected to the master station 12. As shown in FIG.

As described above, the master station 12 has the RS-232C
It has an interface function and has a connector 37 which is a connection part.

Reference numeral 38 denotes a connector provided on the converter side.
It is connected to the connector 37. Reference numeral 39 denotes a termination switch for connecting an internal termination resistor, which will be described later, when connected to the start or end of the transmission line 13. Reference numeral 40 denotes a terminal block for connecting the transmission line 13.

FIG. 5 is a block diagram showing the structure of the master station 12. As shown in FIG.

The master station 12 has a CPU 46 as a central processing unit, a keyboard 41 for performing various operations, and a keyboard I / F 301 for interfacing with an internal circuit, in addition to the RS-232 CI / F (interface) 45 as the communication interface. , A CRTI / F 48 for displaying various processing results, and a CRT 42, and a printer I which is an interface for printing various results on paper.
/ F49 and printer 43, floppy disk drive (FD) I / F50 for storing a large amount of various programs and data, and floppy disk (FD)
It comprises a device 44, a memory 47 for temporarily storing programs and data, and a power supply unit 51 for supplying power to each unit.

The master station 12 shown in FIG. 4 has a structure in which the printer 43 is separated and other parts are integrated. Master station 12
As another example, a keyboard 41, a CRT 42, an FD device 44, and a printer 43 are separately provided, and such a configuration may be used.

FIG. 6 is a block diagram showing the structure of a repeater (amplifier).

Reference numerals 52 and 53 denote a pair of signal lines provided in the transmission line 13, and reference numeral 54 denotes a shield for preventing external noise. The signals on the signal lines 52 and 53 are RS-
It operates in the differential type of 485 standard and has polarity. 5
Reference numeral 5 denotes a terminating resistor, which closes the terminating switch 302 and connects between the signal lines 52 and 53 when the repeater 36 is connected to the start or end of the transmission line 13.

This is because if the transmission line 13 is long, signal reflection or
Crosstalk occurs and normal transmission cannot be performed, so that transmission characteristics are improved, and so-called impedance matching is performed.

Reference numeral 56 denotes a driver / receiver RS-485.
This is an interface element. Reference numeral 303 denotes a receiver (reception unit), and reference numeral 304 denotes a driver (transmission unit). Reference numeral 57 denotes a polarity detection circuit, which detects the direction of the start bit of the transmission signal so that the signal lines 52 and 53 of the transmission line 13 may be connected in reverse, and sets the output line to the normal direction. 59
And the driver 304 is enabled (enabled) by the output line 305.

The transmission line 13, the termination resistor 55, the termination switch 302, the driver / receiver 56, the polarity detection circuit 57, the output line 58 of the receiver 303, and the polarity detection circuit 57
The output lines 59 and 305 are provided in two sets, and are transmitted to the right (R) side when received from the left (L) side in the figure, and transmitted to the left side when received from the right side. It is.

An OR gate 62 receives the output line 305 of the polarity detection circuit 57 as an input and is connected to the frequency dividing circuit 64. The frequency dividing circuit 64 generates a time corresponding to one word length of the transmission signal based on the frequency of the OSC (oscillator) 60. When the polarity detecting circuit 57 detects the start bit, the output line 305 and the OR gate The operation starts via the node 62, and when the time reaches one word length, the polarity detection circuit 5 via the NOR gate 65.
7 is initialized (reset). 63 is a reset circuit for initializing the polarity detection circuit at power-on. Reference numeral 61 denotes a power supply circuit for supplying power to the internal elements of the repeater.

The operation of the repeater thus configured will be described. When the power is turned on, the polarity detection circuit is initialized, the driver 304 is set to a high resistance state by the output line 305, and the receiver is set to the reception state. (Standby state) Here, for example, when transmission is performed from the left (L) side of the transmission line 13, the transmission is transmitted to the driver 304 on the R side via the polarity detection circuit 57 of the receiver 303 of the left (L) example. At this time, the driver 304 on the right (R) side is enabled by the output line 305, and the receiver 303 on the right (R) side is disabled (disabled). At the same time, the frequency dividing circuit 64 starts operating, and after a time corresponding to one word length, the polarity detecting circuit 57 is initialized, the right (R) driver 304 is disabled by the output line 305, and the receiver 303 can receive. State.

Even when a signal is received from the right (R) side, the signal is transmitted to the left (L) side by the same operation as described above.

By the way, the time of one word length of the transmission signal changes depending on the transmission speed, but it can be dealt with by providing a switch or the like in the frequency dividing circuit.

With the repeater 36 configured as described above, the transmission waveform is shaped and amplified, and the system can be made longer. However, the repeater 36 does not need the device address number (device number). Since there is an intermediary for receiving and transmitting from either direction, it can be arranged at any position in the system and can be branched in multiple directions.

On the other hand, when the branch wiring is performed in the above-described RS-485 system bus connection (serial connection), there is a problem due to reflection of the transmission line, and the terminal control devices must be routed in series and wired. Therefore, the wiring distance becomes long, which is uneconomical. In this embodiment, the total length of the transmission line 13 can be shortened by the repeater 36 as compared with the conventional case, and there is an effect that the wiring can be performed economically.

Next, FIG. 7 illustrates an external configuration of an embodiment of a power supply monitoring and control unit according to the present invention. The power monitoring control unit 10 is housed in a case 213. Case 21
There are two examples of an in-panel type 3 and an in-panel embedded type, and FIG. 7 shows an in-panel type. A display unit 17 for a user interface and an operation unit 18 are arranged on the front. Output terminals such as a monitoring control information input terminal, a control power supply terminal, an input / output terminal to a transmission line, and an alarm contact of various power distribution devices are configured by screw-type terminal blocks, and are disposed in upper and lower terminal portions 66.

FIG. 8 is a block diagram for each function of the embodiment. CT7 and other monitoring inputs 68 include current,
There are an analog signal input 70 such as a voltage, a digital signal input 73 such as a contact signal, and a pulse signal input 76 such as an integrating wattmeter signal.

Since the analog signal input 70 contains a distorted AC waveform, it is converted into a level signal corresponding to the effective value by an effective value converter 71, and an A / D (analog-digital) converter 72
Is converted into a digital signal. The CPU 28 reads this and performs arithmetic processing. Since the digital signal input 73 also includes a signal to which noise has been applied, the digital signal input 73 is insulated by the insulating circuit unit 74 and converted into a signal from which noise has been removed by the waveform shaping unit 75. The CPU 28 reads this and performs arithmetic processing. The input of the pulse signal 76 is converted into an internal signal by the insulating circuit unit 77 and the waveform shaping unit 78 in the same manner as the digital signal input 73,
The arithmetic processing is performed by the PU 28.

Reference numeral 16 denotes a transmission interface for connection with a higher-level device such as a master station, which receives commands from a higher-level device and transmits necessary internal data. Device address setting unit 2 for specifying a terminal device during transmission / reception
0 is provided, and the CPU 28 recognizes this set value and performs a selective reception process on a command to the terminal. FIG. 9 shows an example of the address. Here, the slave station (temporary master station) is defined as a device address so that when a plurality of master stations are connected, there is no simultaneous transmission between the master stations. The test address is provided for performing self-diagnosis and the like of the slave station.

In FIG. 8, the control program and calculation data of the CPU 28 are stored and held in the storage unit 31 and the ROM 281 and the RAM 282 built in the chip of the CPU 28. The user can display desired monitor control information on the display unit 17 by operating the operation unit 18.

Reference numeral 15 denotes a power supply line, and reference numeral 27 denotes a power supply unit, which converts and supplies necessary voltages to each unit. The driver 32 is driven by the calculation result of the CPU 28 or a command from the host, and the alarm contact 19 is operated to output an output to the control output 69. Similarly, in this embodiment, a termination resistance control output section 67 is provided, and connection / non-connection of the termination resistance can be controlled from a higher level.

FIG. 10 shows a basic communication procedure between the master station 12 and the power supply monitoring control unit 10 (displayed as a slave station). The procedure conforms to the basic transmission control procedure of JIS (X5002).
In the selecting method, the master station operates as the master station.

In normal communication, the master station sends a command message to the slave station as shown in FIG. 10 (1). The command message is composed of a text consisting of a slave station address, a command and data accompanying the command. On the other hand, the slave station performs control corresponding to the command request, and transmits a corresponding response message to the master station. The response message is composed of a text including a slave station address, a response (effective completion), a command, and monitoring control information data corresponding to the command request.

When a command error occurs when the command is not appropriate, a response (non-execution) and a message including an error code are transmitted to the incorrect command of the master station as shown in (2) of FIG.

When a failure such as a communication error occurs, as shown in (3) of FIG. 10, in this embodiment, in order to simplify the control, collision of responses on the transmission line is avoided as no response. There are various transmission control procedures at the time of such an abnormality depending on the system level.

FIG. 11 shows an example of a transmission / reception message. FIG. 7A shows the structure of a received message of the slave station, and FIG.
4 shows the configuration of a transmission message of the slave station, and FIG. 4C shows the content of the message.

DLE, STX and ETX are transmission control characters. The address indicates the address of the slave station as shown in FIG. The command is for requesting transmission of monitoring control information and controlling the alarm contact 19, and includes, for example, the command shown in FIG. The response indicates the command execution status of the slave station and is included only in the slave station transmission message. The data in the slave station received message is for transmitting a plurality of data from the master station, and is not normally required. The data in the slave station transmission message is supervisory control information of the slave station. BCC is a block check character,
It is added for the purpose of detecting transmission errors.

FIG. 12 shows an example of a command communication direction and its contents.

FIG. 13 shows a case where the master station 12 is in the monitoring room and a plurality of power supply monitoring control units 10, 10-2, 10-3, 1
This is an example where 0-4 are connected. In this example, the power supply monitoring control units 10-3 and 10-4 are located farther from the monitoring room, and are connected via the repeater 36. In a normal state, the termination switch 39 of the converter 35 attached to the master station 12 in the monitoring room as a termination resistor and the termination switch 39 of the power supply monitoring control unit 10-4 at the end of the transmission line are closed to form a transmission loop. doing.

In such a system, it is desired to connect a master station near the power supply monitoring and control unit 10-4 to perform monitoring or the like, but the master station 12 in the monitoring room is stationary and is inconvenient to carry. At this time, a temporary system can be configured by connecting the portable master station 12 'which is convenient to carry like a broken line. When the master station 12 is portable and can be carried from the monitoring room, it can be used as the master station 12 '.
The end (start) position of 3 becomes the power supply monitoring and control unit 10 and the end switch 39 at this position needs to be turned on.

FIG. 14 shows an example of a termination resistance control processing flow when the termination resistance is controlled. First, the master station is turned on (a), performs initial processing (b), and enters a standby state (c). If a key is operated (input of a slave station address number, input of a termination resistance control command, ON information, etc.) immediately before carrying the master station 12, the following processing is performed by a key interrupt.

First, it is determined whether or not a series of key operations for transmitting a termination resistance control command have been performed (2), and Ye
If s, the process proceeds to E, and if No, the process proceeds to another corresponding process. In (e), it is determined whether the terminating resistor included in the above series of key operations is to be turned on or off.
If this is the case, the information 01H of (f) is set, and if it is OFF, the information 00H is set (g).
Go to (f) to turn on the terminating resistor 39 of the information 01
Set H, (h) combine a series of transmission characters,
It is determined whether transmission is possible in (i) and transmission is performed in (nu).

On the other hand, slave stations 10, 10-2, 10-3, 10
In -4, reception is performed (l), it is determined whether or not the device addresses match (ヲ). If they match, the process proceeds to (w). In this case, the slave station 10 matches and the next process (w) is performed. Move on. On the other hand, the processing ends because the other slave stations do not match.

In (W), the received control command (command)
Is analyzed to determine whether it is a termination resistance control command (f) Y
If es, the process proceeds to (Y), and if No, another process is performed. In (Y), it is determined whether the ON information is OFF information. In this example, since the ON information is ON information, the process proceeds to (T), and FIG.
"ON" information is output to the termination resistance control output section 67 shown in FIG.

After performing this series of operations, master station 12
The transmission lines 13 to 35 are separated from each other, moved, and used as the master station 12 '.

FIG. 15 is a transmission control flow for performing control with the master station 12 when the master station 12 'is connected in FIG. The additionally connected master station 12 'is shown as a slave station (temporary master station). The slave station (temporary master station) 12 'sends a transmission non-permission command to the master station 12 to prevent conflicts in transmission between the master stations.

On the other hand, when disconnecting the temporary master station 12 ', a transmission permission command is sent from the temporary master station 12' to the master station 12;
The master station can be restored.

First, when the slave station 12 ', which is the temporary master station, performs a key input for disabling transmission of the address number input of the master station (master station) 12, a key interrupt occurs as shown in FIG. , (S) to determine whether it is a master station transmission control command, and Y
If it is es, the process proceeds to (T). If it is No, the process proceeds to another process. In (T), a determination is made as to whether the command is a transmission permission command or a non-permission command. In (n), "80" is used as data accompanying the command.
The information is set to transmit "H", a series of these transmission characters are synthesized in (a), it is determined whether or not transmission is possible in (m). (C) If Yes, the transmission is performed, and the transmission process is completed. On the other hand, if the transmission is permitted in (T), the process proceeds to (N), information is set to transmit “00H” as data accompanying the command, and the process proceeds to (A).

On the other hand, the master station 12 receives the above series of transmission characters (f), determines whether the device addresses match (no), and if yes, moves to (e) and analyzes the control command ( E) If No, the process ends.

As a result of the control command analysis, it is determined whether or not the command is a master station transmission control command. (H) If Yes, the process proceeds to (Y) to determine whether transmission is permitted or not. Move to (M), but in this example, since it is a non-permission instruction, N
In step (e), the transmission non-permission flag is set, and the master station 12
Will be banned from transmission from now on.

Accordingly, a plurality of master stations can be connected to any position in the network, and a system with high workability and maintainability can be provided.

FIGS. 16, 17, 18 and 19 show the internal block diagram of the power supply monitoring and control unit 10 shown in FIG. 8 in further detail.

FIG. 16 is a block diagram showing the input of an analog signal. 83 is a current / voltage conversion circuit for outputting a voltage proportional to the current extracted by the ZCT4 and the current extracted by the CT7 and further transformed by the internal CT22; 84 is a current, a ground fault current; Analog multiplexers 85 and 89 for selecting a voltage and a harmonic current are RMS (Root Mean) for converting an AC waveform of the selected analog signal into a DC effective value.
Square) / DC converter, 86 and 90 are RMS
Amplifying circuits for amplifying the effective value signals output from the / DC converters 85 and 89;
A protection circuit for preventing the next stage circuit from being destroyed by the output voltage; 88, an A / D converter for digitally converting the effective value signal output from the protection circuits 87, 91; 94, a current output from the analog multiplexer 84; A harmonic current extraction circuit that cuts only the fundamental wave of the signal and extracts a harmonic component current, a voltage zero cross detection circuit 95 that changes a digital waveform every time a voltage waveform between the phases crosses zero voltage, and a current waveform 97 that has a current waveform A current zero-cross detection circuit that changes a digital waveform every time a zero potential is crossed, 96
And 98 are protection circuits for preventing the next stage circuit from being broken by signals output from the voltage zero cross circuit 95 and the current zero cross circuit 97.

Reference numerals 99 and 100 denote a temperature measurement interface 25, 99 denotes a resistance / voltage conversion circuit for converting the resistance value of the resistance temperature detector 14 into a voltage, and 100 denotes a voltage output from the resistance / voltage conversion circuit 99. This is a protection circuit for preventing the destruction of the next stage circuit due to the above.

Reference numeral 92 denotes an AND between a decoder output from the CPU 28 and the write signal WR, and a negative logic input AND for outputting a signal for starting A / D conversion of the A / D converter 88. Reference numeral 93 denotes a decoder signal from the CPU 28. And a negative logic input AND which takes the AND of the read signal RD, outputs digital data from the A / D converter 88, and enables reading from the CPU 28.

The provision of the RMS / DC converters 85 and 89 in the CPU 28 and the display of the average value of the absolute value of the AC waveform on the display unit 17 by expressing the effective value in the CPU 28 means expressing the work of electricity by the method of capturing and displaying the average value. Is a faithful measurement method, and is more accurate than a method in which an input value is assumed to be a sine wave and an effective value is displayed assuming that the input value is a sine wave as shown by the following formula.

The average value Iav of the sine wave is

[0088]

(Equation 1)

In the case of the above equation, if the input is an AC input, the average value per cycle becomes zero.

[0090]

(Equation 2)

The effective value Ir of the sine wave is the calorific value when an AC current i is applied to a fixed resistor R for one cycle, and the calorific value when the DC current I is applied to a fixed resistor R for one cycle. Is determined as the effective value Ir of the AC current i, so that

[0092]

(Equation 3)

[0093]

(Equation 4)

[0094]

(Equation 5)

From Equations 2 and 5, Ir based on Iav is obtained.

From the equation (2)

[0097]

(Equation 6)

By substituting equation (6) into equation (5),

[0099]

(Equation 7)

Therefore, the effective value can be calculated from the average value according to Expression 7.

FIG. 17 is a block diagram of digital input / output. 101 is a DC switch, 102 is a signal DC power supply which is an external drive power supply of the DC switch 101,
Reference numeral 103 denotes a signal power supply switching circuit which can switch between an external signal DC power supply 102 for driving the DC switch 101 and an internal power supply, 106 denotes an AC switch, 107
, A signal AC power supply which is an external drive power supply for the AC switch 106; and 104, 108 such as photocouplers for electrically isolating signals from the DC switch 101 and the AC switch 106 and peripheral circuits of the next CPU 28. Insulating circuits, 105 and 109 are light emitting elements for digital input display for displaying the presence or absence of signals from the DC switch 101 and the AC switch 106, and 401 and 402 are DC switches 1
01 and a waveform shaping circuit by a chattering elimination, Schmitt, and trigger circuit included in the input signal from the AC switch 106.

Reference numeral 110 denotes an active power pulse input from a pulse input type active watt-hour meter, and 111 denotes a reactive power pulse input from a pulse input type reactive watt-hour meter.

Reference numerals 112 to 119 indicate the pulse interface 26.

Reference numerals 112 and 117 denote active power pulse input 1
10. Insulation circuit such as a photocoupler for electrically isolating the signal from the reactive power pulse input 111 and the peripheral circuit of the next CPU 28. Reference numerals 113 and 118 denote the active power pulse input 110 and the reactive power pulse input 111. Active / reactive power pulse input light emitting elements for indicating the presence / absence of a signal, 114 and 119 are chattering elimination, Schmitt and trigger included in the input signals from the active power pulse input 110 and the reactive power pulse input 111 A waveform shaping circuit by a circuit, 115 is a counter for counting the number of pulse inputs of the active power pulse input 110 and the reactive power pulse input 111 in binary, and 116 is a binary count value output from the counter 115 from the CPU 28. It can be put on the data bus 34 connected to the CPU 28 by the decoder output. Is Ffa.

Reference numeral 122 denotes a drive circuit for driving the alarm contact 19 in response to an output command for the alarm contact 19 from the CPU 28, reference numeral 123 denotes a light emitting element for displaying the presence or absence of an output command for the alarm contact 19 from the CPU 28, and reference numeral 121 denotes the drive circuit 1.
An insulation circuit such as a photocoupler for electrically insulating the signal 22 from the next-stage alarm contact 19, and 120 is a relay constituting the alarm contact 19.

FIG. 18 is a block diagram showing the periphery of the CPU 28. 39, 55, 56, 124 to 126 are block diagrams showing the inside of the transmission interface 16.

Reference numeral 124 denotes a transmission / reception control signal and transmission data driving circuit; 125, an insulation circuit for insulating the transmission / reception control signal, transmission data, and reception data between the CPU 28 and the transmission line 13; and 56, a driver such as RS-485. 126, a protection circuit for preventing the driver / receiver 56 from being destroyed by an abnormal voltage that may be input from the transmission line, and 55 a terminal unit or 55 for preventing reflection of a transmission signal generated in the terminal unit in the bus connection. A terminating resistor 39 matching the impedance on the transmission line required for the starting end unit, and a terminating switch 39 for switching according to the necessity / unnecessity of the terminating resistor 55.

127 is a vibrator which is a basic operation clock of the CPU 28, 129 is a storage unit 31, a display unit driver 2
9, negative logic AND9 for controlling the A / D converter 88
2, 93 and the binary count value of the integrated electric energy
Buffer 1 that can be placed on the data bus to 28
16 is connected to a decoder capable of decoding the control of the CPU 28.

Reference numerals 130 and 131 denote internal blocks of the storage unit 31, reference numeral 130 denotes a nonvolatile memory EEPROM readable / writable from the CPU 28, and reference numeral 131 denotes a CPU 2
8 is a non-volatile memory EPROM that can only be read.

When FIG. 18 corresponds to FIG. 2, the display unit driver 29 is a buffer 132 with a latch function in this embodiment, the display unit 17 is a numeric display light emitting element 133 and a light emitting element 134, and the operation unit 18 is The key switch 137 and the device address setting unit 20 are a rotary switch 138.

The power supply monitoring unit 1 configured as described above
0 is provided with the termination switch 39, so that there is no need to be aware of which power supply monitoring and control unit 10 is the termination, and the switching can be performed after the wiring work is completed. As a result, when the terminal unit is changed at the time of expansion, the unit which has been the terminal until now is not brought to the terminal and wired, and it is possible to cope with which unit becomes the terminal.

Further, by providing the EEPROM,
Even if the control power supply 15 of the power supply monitoring unit 10 is cut off, the contents set by the customer, measured values, and the like remain in a non-volatile manner, so that resetting after the control power supply 15 is restored is unnecessary, and the measurement result can be read. Become.

FIG. 19 is an internal block diagram of the power supply unit 27.

139 is AC85V to 264V, and D is
AC / DC converters that can withstand C110V and wide-range input control power supply 15, 140, 141, 14
2 is a DC / DC converter that outputs +12 V, ± 15 V, and 5 V (A15 V) for transmission with respect to a single input,
Reference numeral 43 denotes a voltage detection circuit capable of detecting the output voltage of the AC / DC converter and outputting a reset signal based on the voltage.

FIG. 20 shows an overall control flow. In the main, communication, display, setting, and measurement modules are controlled in a time-sharing manner. When each of the above modules is in the operation prohibited state, the check module is operated.

As the interrupt processing, an interrupt (IRQ) from the above-mentioned zero-cross circuit, a fixed-cycle interrupt (ICI) of three types of timers (CMI), (OCI), an interrupt from a transmission circuit (SIO), etc. Interrupt processing.

FIG. 21 shows a communication module flow. The communication module checks the message (d), returns no response when a communication error is detected (te), and ends. When the message is normal, a command check is performed (A), and when a command error is detected, a response indicating a command error is transmitted (M), and the process ends. When the command is normal, the command processing corresponding to the command is performed (G). If there is response data, the data and the response indicating the normal command are transmitted (U), and the process ends.

FIG. 22 shows a display module flow. The display module checks (M) whether there is a display item change instruction by pressing the display push button switch, and if there is no change instruction, shifts to data conversion processing (H). If there is a change instruction, the display item corresponding to the pressed push button switch is analyzed (S), and the item is set to L.
This is shown on the ED display (d).

Next, the data stored in the designated display item is converted into data for display on the numerical display (e), and the numerical display is performed (e).

FIG. 23 shows a setting module flow. The setting module checks whether there is a setting item change instruction by pressing the setting push button switch (A), and terminates if there is no change instruction. If there is a change instruction, the setting item corresponding to the pressed push button switch is analyzed (Yes), and the item is displayed on the LED display (U). Next, by pressing the push button switch, the setting data is input (E), and the value is displayed on the numeric display (O). Further, when the push button switch is depressed, the value is stored after the confirmation (?), And the process ends.

FIG. 24 shows a flow of the measurement module. In the measurement module, input each analog data
Calculate each measurement item (ke) and finish.

FIG. 25 shows a check module flow. In the check module, ROM sum check,
The stack pointer is checked (this), (sa).

FIG. 26 shows a timer interrupt processing flow.

In the timer interruption process, the operation status of each timer is checked (S), the elapsed value is updated (S), and the process corresponding to each timer is performed at the time of timeout (T).

FIG. 27 shows an SIO interrupt processing flow. S
The IO interrupt processing includes a transmission interrupt processing and a reception interrupt processing.

In the transmission interruption processing, the DL which enables the transmission of the binary code in accordance with the basic procedure and the transmission mode is used.
Perform double transmission of E code, calculate block check code (BCC) for error check, etc.
(H).

In the reception interruption processing, the message reception check, the above-described DL
E One character is deleted at the time of double reception, and the communication module is started at the time of normal message reception (F) to (M).

Further, communication errors such as a parity error, an overrun error, and a framing error are checked as reception errors.

FIG. 28 shows an example of the slave station communication state matrix.
FIG. 29 shows an example of the master station communication state matrix.

Next, a specific measuring method for the analog signal shown in FIG. 16 will be described with reference to FIGS.

FIG. 30 shows a current measuring circuit.

CT7 installed in the R and T phases of the measured circuit
The primary current is taken out and is passed through the internal CT 22 as an internal CT primary wire 144 to be transformed and the secondary C
T current is obtained. In this case, since the CT 7 is not installed on the S-phase electric wire that is the intermediate phase, the S-phase current measurement employs a method of indirectly performing measurement.

The internal primary wire 144, which is the output from the CT 7 installed in each of the R and T phases, is passed through one internal CT 22. Thus, the S phase can be indirectly measured by the vector sum of the R and T phase currents. (However, only when it is assumed that the ground fault current Iz = 0) The principle of the S-phase indirect measurement is shown by a calculation formula.

[0134]

(Equation 8)

[0135]

(Equation 9)

[0136]

(Equation 10)

[0137]

[Equation 11]

[0138]

(Equation 12)

Here, it is assumed that the relationship between IR, IS and IT is ideal, and IZ = 0.

[0140]

(Equation 13)

[0141]

[Equation 14]

Secondary C, each of which is transformed by internal CT22
The T current is a current / voltage conversion circuit (load resistance in the embodiment).
83 allows the current to be output as a voltage.
The current converted into a voltage for each phase (by Ohm's law: V = IR) is converted by the analog multiplexer 84 into the CPU 2.
8, one of the phases is selected by the control command from R,
After being input to the MS / DC converter 85 and subjected to effective value conversion, the signal is amplified by the amplifier circuit 86, the peak voltage is regulated by the protection circuit 87, then converted to a digital value by the A / D converter 88, and can be read by the CPU 28. Become.

FIG. 3 shows a current measurement flow as viewed from the CPU 28.
It is shown in FIG.

First, the current value is digitally converted by the current measuring circuit and read as x (31-a). With respect to this x, it is possible to calculate and obtain the measured current value y from the current conversion count a and the current conversion offset current b obtained by circuit constant calculation or actual measurement (31−
b) and y can be stored (31-c) in the memory 31 and displayed.

When the current transformation ratio P1 of CT7 changes,
The current ratio can be set by the customer, and the current value can be obtained by the following equation.

[0146]

(Equation 15)

FIG. 32 shows a voltage measuring circuit.

P connected to the R, S, and T phases of the measured circuit
The primary voltage is taken out by T5 and transformed by connection with the internal PT23 to obtain a secondary PT voltage. A secondary voltage, which is a voltage for each phase, is converted to C by an analog multiplexer 84.
RMS / D is selected by the control instruction from PU28.
After being input to the C converter 89 and subjected to effective value conversion, the voltage is amplified by the amplifier circuit 90 and the peak voltage is regulated by the protection circuit 91. Then, the digital value is converted by the A / D converter 88 to be readable by the CPU 28. CP
FIG. 33 shows a voltage measurement flow viewed from U28.

First, the voltage value is digitally converted by the voltage measurement circuit and read as v (33-a). With respect to this v, it is possible to calculate and obtain the measured voltage value y from the voltage conversion coefficient e and the voltage conversion offset voltage f obtained by circuit constant calculation or actual measurement (33-
b) and y can be stored (33-c) in the memory 31 and displayed.

When the metamorphic ratio P2 of PT5 changes,
The transformation ratio can be set by the customer, and the voltage value can be obtained by the following equation.

[0151]

(Equation 16)

FIG. 34 shows a ground fault current measuring circuit. As can be seen from Equation 8, since the vector sum of each phase current is the ground fault current Iz, the ground fault current can be extracted by installing the ZCT 4 in the R, S, and T phases of the measured circuit. This ground fault current is converted into a current / voltage conversion circuit (load resistance in the embodiment) 146.
Can output a current as a voltage (Ohm's law: V = IR). The voltage-converted ground fault current is selected by the analog multiplexer 84 in accordance with a control command from the CPU 28, input to the RMS / DC converter 85, and subjected to effective value conversion, and then amplified by the amplifier circuit 86 and amplified by the protection circuit 87. After the peak voltage is regulated, it is converted into a digital value by the A / D converter 88 and can be read by the CPU 28.

FIG. 35 shows a ground fault current measurement flow as viewed from the CPU 28. First, the ground fault current value is digitally converted by the ground fault current measurement circuit and read as iz. With respect to this iz, it is possible to calculate and obtain a measured ground fault current value y using a ground fault current conversion coefficient c and a ground fault current offset current d obtained by circuit constant calculation or actual measurement,
y can be stored in the memory 31 and displayed.

When the current transformation ratio P3 of the ZCT 4 changes, the current transformation ratio can be set by the customer, and the ground fault current value can be obtained by the following equation.

[0155]

[Equation 17]

FIG. 36 shows the internal configuration of the voltage zero-cross circuit 95 and the current zero-cross circuit 97. 149 and 151 are input resistors, 152 and 157 are pull-up resistors, 150 is a diode for supplying current when a negative voltage is applied, and 153 and 154.
Denotes a zero-cross reference voltage setting resistor, 155 denotes a comparator, 156 denotes a feedback resistor, 158 denotes a noise removing capacitor, and 159 denotes a protection diode. Part A is a-(minus) terminal of the comparator 155, and part B is a + (plus) terminal of the comparator 155.

Consider a case where the forward voltage of the diode 150 is set to VD, and a current transformation voltage waveform is input to the IN terminal. The input voltage is represented by Vin · sin θ, and VD <Vi
The voltage VAH of the portion A in the circuit diagram in a range where the relationship of n · sin θ can be maintained is

[0158]

(Equation 18)

In the range where the relationship of VD ≧ Vin · sin θ can be maintained, the voltage VAL of the portion B in the circuit diagram is

[0160]

[Equation 19]

Can be expressed as follows.

When the voltage at the portion A of the comparator 155 is lower than the voltage at the portion B, the output of the comparator 155 is at the H level. Conversely, when the voltage at the portion A is higher than the voltage at the portion B, the comparator 155 Is at L level.

The reference voltage at the + terminal has the following two values depending on the output level of the comparator 155 since the feedback resistor 156 is provided.

(1) Reference voltage VBL when output of comparator 155 is L

[0165]

(Equation 20)

(2) Reference voltage VBH when the output of the comparator 155 is H

[0167]

(Equation 21)

The zero-cross circuit is composed of R, T phases and ZCT.
4, the ground fault phase can be determined by Equation 8. (Assuming that the phase relation between the R and T phases is 120 degrees, the zero cross circuit of the R or T phase and the ZCT4
The ground fault phase can be determined by the zero cross circuit. FIG. 37 shows a period measurement flow for frequency measurement. FIG.
When an interrupt from the voltage zero cross circuit 95 shown in FIG. 37 occurs, the cycle is taken out according to the cycle measurement flow of FIG.
7-c), the value is converted to a frequency value by the frequency measurement flow of FIG. 38 (38-b) and stored (38-c).
c).

When the display of the frequency is selected by pressing the display selection key 137e in FIG.
When the ED display is turned on, it indicates that the frequency is being displayed, and the value is displayed on the numeral displays 133a to 133f.

Further, it is possible to read out the frequency values stored in the ten slave stations by a command from the twelve master stations connected in the system configuration as shown in FIG.

Next, FIGS. 39 and 40 show the power factor, active power,
4 shows a time difference measurement flow and a phase difference measurement flow for obtaining reactive power and the like.

The time difference measurement flow is similar to that shown in FIG. 37 when an interrupt from the current zero cross circuit shown in FIG. 36 occurs.
This value is converted into a phase difference by the phase difference measurement flow of FIG. 40, and this value is compared with the current stored in FIG. 31 and FIG.
The active power and the reactive power are calculated from the voltage values according to the active power and reactive power measurement flow in FIG. 43 and stored.

Further, by setting the rated power capacity in advance, the usage rate is calculated and stored according to the usage rate measurement flow of FIG.

When the display of the usage rate is selected by pressing the display selection key 137h in FIG.
Lighting of the ED display indicates that the usage rate is displayed, and the value is displayed on the numeral displays 133a to 133f.

Further, it is possible to read out the utilization ratio values stored in the ten slave stations by commands from the twelve master stations connected in the system configuration as shown in FIG. As a result, the usage rate with respect to the rated capacity of the transformer 2 is obtained. If the usage rate is low, the transformer 2 is replaced with a smaller capacity transformer or integrated with another transformer (not shown). Thus, unnecessary loss can be reduced by reducing the number of transformers, and power saving of the distribution system can be achieved. Further, when the usage rate is high, the load is optimized by replacing the transformer 2 with one having a large capacity, so that the life of the transformer 2 can be extended.

When the transformer 2 is replaced with a smaller capacity transformer, it is important to control the temperature when the load increases.
FIG. 66 shows a temperature measurement flow of the transformer 2 in such a case. The CPU 28 determines the temperature measuring resistor 1 at (66-a) in the figure.
A / D output of temperature measurement interface 25 connected to
The converted value is input, the temperature is obtained by the conversion formula shown in (66-b), and the value is stored in (66-c).

When the display of the electric energy charge is selected by pressing the display selection key 137d in FIG.
Is turned on, indicating that the electric energy is being displayed, and the value is displayed on the numeral displays 133a to 133f.

Further, it is possible to read out the electric energy charges stored in the ten slave stations by a command from the twelve master stations connected in the system configuration as shown in FIG.

The following describes the measurement of power, the measurement of the usage rate, the measurement of the amount of power, and the calculation of the power rate.

FIG. 43 shows a flow of measuring apparent power, active power, and reactive power. The values of each phase current, each phase voltage, sine and cosine stored at (43-a) in the figure are read out,
According to the conversion formula shown in (43-b), the apparent power, the active power,
The reactive power is obtained, and the value is stored in (43-c).

FIG. 44 shows a usage rate measurement flow. The values of the apparent power and the rated power capacity stored at (44-a) in the figure are read, the usage rate is obtained by the conversion formula shown at (44-b), and the values are stored at (44-c). I do.

FIG. 45 shows a power amount measurement flow. In the measurement of the electric energy, the value input by the pulse interface 26 shown in FIG. 2 is converted by the electric energy measurement flow of FIG. 45 and stored. At (45-a) in the figure, the pulse count value is input from the power amount measuring circuit, and the stored value of the power amount conversion coefficient is read out, and the power amount is obtained by the conversion formula (45-b). , (45-c) to store the value.

FIG. 46 shows a flow chart of the electricity charge calculation. The calculation of the power rate is performed by setting the unit price of the power rate and calculating and storing the power rate according to the power rate calculation flow of FIG. The power amount and the value of the charge calculation parameter stored at (46-a) in the figure are read out, the power amount charge is obtained by the calculation formula shown in (46-b), and the values are calculated by (46-c). Remember.

The measurement of the power factor, the accumulation of the apparent power, and the measurement of the load factor will be described below.

FIG. 67 shows a power factor measurement flow. The values of the phase difference and cosine stored at (67-a) in the figure are read out, and the power factor is obtained by the conversion formula shown in (67-b), and
In 7-c), the phase lag or advance is judged. In the case of phase advance, the sign is reversed as shown in (67-d), and (67-c).
The value is stored in e).

FIG. 68 shows the apparent power accumulation flow. The current value, the cumulative value, the cumulative number, and the maximum value of the apparent power stored at (68-a) in the figure are read, and the cumulative value and the cumulative number are updated by the equation (68-b). , (68-c)
To compare the current value and the maximum value. If the current value is larger than the maximum value, the maximum value is updated as shown in (68-d), and (6
The value is stored in 8-e).

FIG. 69 shows a flow chart of the load factor measurement. The value of the accumulated value, the number of times of accumulation, and the maximum value of the apparent power stored at (69-a) in the figure are read out, and the load factor is obtained by the conversion formula shown in (69-b), and (69-c) Memorize the value with
At (69-d), the accumulated value, the accumulated number, and the maximum value of the apparent power are cleared to zero.

FIG. 41 shows a harmonic current measuring circuit. FIG.
In the current measurement circuit of 0, the current value taken into the A port of the analog multiplexer 84 and voltage-converted for each phase is selected from one of the A ports by a control command from the CPU 28, After only the harmonic components are extracted by the harmonic current extraction circuit 94 composed of circuits up to 199, the harmonic components are again input to the B port of the analog multiplexer 84 and output from the B port of the analog multiplexer 84 according to the control command from the CPU 28. And RMS / D
After being input to the C converter 89 and subjected to the effective value conversion, the amplification circuit 90 amplifies and the peak voltage is regulated by the protection circuit 91, and then is converted into a digital value by the A / D converter 88 and can be read by the CPU 28. .

The inside of the harmonic current extracting circuit 94 will be described. First, a current value converted into a voltage passes through a twin T-type filter that realizes a band, an eliminator, and a filter composed of three stages. First, the input fundamental frequency is 50/6
This filter removes the 50 Hz band from 0 Hz.
64 to 175. The second stage is a filter for removing a 55 Hz band which is an intermediate band of the input fundamental frequency of 50/60 Hz, and is constituted by 176 to 187 in the figure. The third stage is a filter for removing a 60 Hz band out of the input fundamental frequency of 50/60 Hz, and is constituted by 188 to 199 in the figure.

The first stage will be described as a representative. Resistance 164
165, 170 and 171 have the same resistance value R [Ω], and the capacitors 166 to 170 also have the same capacitance C [F]. This dip frequency f (the frequency with the largest attenuation) is

[0191]

(Equation 22)

When the dip frequency f is input, at the point A, the phase is delayed by 45 degrees with respect to the input, and at the point B, the phase is advanced by 45 degrees with respect to the input. Therefore, the phase point between A and B becomes 90 degrees, the current flowing through the resistor 165 and the capacitor 167 is canceled, and does not appear at the point C. 172 and 173 are buffer amplifiers, and 173 performs feedback. Reference numerals 74 and 75 denote resistors for determining the feedback ratio. In the relationship of R74≫R75, the feedback ratio is small and the removal band is wide. In the relationship of R74≪R75, the feedback rate is large and a sharp band characteristic is exhibited.

FIG. 42 shows the harmonic transmission filter characteristics.
There are removal bands at 50 Hz, 55 Hz and 60 Hz, and there is almost no attenuation in the second harmonic band of the fundamental wave.

As described above, by removing only the fundamental wave, the remaining band component can be taken in as a harmonic current.

FIG. 65 shows a harmonic current measurement flow. The value obtained by A / D conversion of the harmonic current from the harmonic current measurement circuit is input at (65-a) in the figure, and the harmonic current is obtained by the conversion formula shown in (65-b), and (65-c) Stores the value.

FIG. 47 shows a display example of measured values. 133
a to f are measurement value display sections; 134a to e and i to m are types of data (current, voltage, etc.) displayed on the measurement value display section, display sections corresponding to display selection keys 137a to 137j, 1
Reference numerals 34f to 34h denote display units corresponding to the data display of the RST phase of the current, voltage, and harmonic current.
This is a display unit that is also used for displaying valid and invalid data of the electric energy. Reference numerals 134h to 134p denote display units indicating the current, maximum, and minimum values of data corresponding to display selection keys displayed on the measurement value display unit, 137a to h denote display selection keys, and 137i denote upper and lower limits of the monitoring state detection state. A key 137j is a monitoring key for switching the display of the measurement value and the monitoring value, and a key 137h is a display switching key for switching the current, maximum, and minimum values of the content displayed on the measurement value display section.

By adopting such a key arrangement and a display structure, each target monitoring element can be viewed with a single touch.

FIG. 48 shows the display switching operation for the R, S, and T phases. By repeatedly pressing the display selection key of 137a, 137b, or 137f, the display contents are switched (R → S → T). Also, the display switching key 137
By repeatedly pressing k, the display contents can be switched (current → maximum → minimum).

Thus, selection of each phase and selection of the current, maximum, and minimum are possible.

FIG. 49 shows key input and display contents. When the display selection keys 137a to 137h are repeatedly pressed, the current of each phase of RST is displayed in the case of current, and RS and S are displayed in the case of voltage.
Displays the voltage of the T and TR phases, displays the effective and invalid values for power and power, displays the power factor and then frequency for power factor and frequency, and displays the current for each phase of RST for harmonic current. In the case of display and temperature ground fault, the temperature and then the ground fault are displayed. Similarly, the load factor and the usage factor are also displayed in order. As for the other display selection keys except for the electric energy, when the display switching key 137k is repeatedly pressed, the current value, the maximum value, and the minimum value of each monitoring element are displayed.

FIG. 50 shows a display example of the monitoring value, and shows a display example of the temperature upper limit monitoring value. When the monitor value key 137j is pressed, the 134m LED display section is turned on, and the monitor value display mode is set. Next, by pressing the display selection key 137g corresponding to the content to be displayed, 134h, 1
34j lights up. At this time, 134h indicates a temperature display, and the setting contents of the monitoring values are displayed in 133a to 133f.

Thus, the monitoring value of each monitoring element can be viewed directly.

FIG. 51 shows a status display. Reference numeral 201 denotes a power indicator (POW. LED), which indicates that power is supplied when the indicator is lit. A CPU status indicator (RUN. LED) 202 indicates that the CPU is operating normally when the indicator is lit. Reference numerals 113 and 118 denote pulse input indicators, 105a, 105b, and 109a to 109c denote digital input indicators, 123a to 123c denote alarm contact output indicators, and 20.
Reference numerals 0a and 200b indicate transmission interface signal indicators.

Thus, the digital input from outside, the transmission / reception data on the transmission line, and the digital output can be directly viewed.

FIG. 52 shows the structure of the operation unit. The operation unit is
137a to 137l, 12 key SWs, 2 rotary SWs, 2 slide SWs 138a, 138b
1 and 39. 21 is a transmission rate switch SW,
Reference numeral 39 denotes a transmission line terminating resistor SW, and 137l, a mode key for switching to a monitoring value setting registration function.
8b denotes a device address setting SW, 138a denotes an upper digit, 138b denotes a transmission line terminating resistor SW39, and the device address setting SW39 is covered by a cover 601 so as not to be operated normally.

FIG. 53 shows the monitor input key. The setting values can be entered by using the display selection keys 137a to 137j and the registration key 13
7k can be entered. At that time, display selection key 1
37a to 137j are also used as numeric keys.
Therefore, the operation of directly inputting the set value is easy.

FIG. 54 shows a terminal arrangement. 203 is a digital input terminal, 204 is a pulse input terminal, 205 is an alarm contact output terminal, 206 is a transmission interface terminal, 20
7 is a power supply input terminal, 208 is a PT temperature detector input terminal, 20
9 denotes a ZCT input terminal, 210 denotes a CT input terminal, and 211 denotes a PT input terminal.

FIG. 55 shows an application of the configuration of the current measuring circuit shown in FIG. CT is applied to the S phase in addition to the R and T phases of the measured circuit.
7 is installed, and primary currents of all phases are taken out and penetrated as internal CT primary wires 144 through internal CTs 22 corresponding to the respective phases, thereby obtaining secondary CT currents. Below C
The fetch operation up to the PU 28 is the same as in FIG.

In this case, since the current value actually flowing in each phase can be directly converted and measured, the accuracy is good, and by providing a zero-cross circuit for each phase, the ZCT4
The ground fault current can be measured and the ground fault phase can be determined even without installing the ground fault current. (Assuming that the current phase difference of each phase is 120 degrees, the measurement of the ground fault current and the determination of the ground fault phase can be performed without the zero cross circuit. See Equation 8).
FIG. 4 is an explanatory diagram of semi-automatic correction of analog input. Problems that occur when an analog waveform is input and read by the CPU 28 as a digital value after various conversions are zero adjustment and span adjustment. If errors occur in the zero point and span aimed at in the design stage due to element errors such as resistance values and capacitor capacitances, and variations in the A / D conversion reference voltage, etc. It is necessary to perform adjustment and span adjustment.

However, in the present embodiment, a constant reference analog input binary value on the maker side or the customer side is given to the operation unit 18.
The correction is performed by the CPU 28 by the setting by the following.

In FIG. 56, five possible characteristic lines are described by taking a current as an example. In this embodiment, the A / D conversion output with respect to the analog input has linearity in principle.

A straight line a is A / D at analog input 0 [A].
The converted output data is "0", indicating that zero adjustment is unnecessary. First, when a reference analog input value 1 [A] was input, the A / D conversion output data was Ya1.
This Ya1 is stored in the memory 31. Next, when another reference analog value 4 [A] was input, the A / D conversion output data was Ya2. This Ya2 is stored in the memory 31. As a result, if the variable of the A / D conversion output data is Da,

[0213]

(Equation 23)

Can be expressed as follows.

A straight line b is A / D at analog input 0 [A].
It can be seen that the converted output data is "0" or more and has a positive offset. Assuming that the reference analog input value is input as in the case of the straight line a and the variable of the A / D conversion output data of the straight line b is Db

[0216]

(Equation 24)

Are represented as follows. Similarly, each A of the straight lines c, d, and e
If the variables of the / D conversion output data are Dc, Dd, and De, each straight line is represented by the following equation.

[0218]

(Equation 25)

[0219]

(Equation 26)

[0220]

[Equation 27]

Formulas were created for the above five straight lines, but the shapes are the same, and a straight line can be represented by one representative formula regardless of the inclination or offset.

[0222]

[Equation 28]

As described above, it is understood that the relationship between the analog input value and the A / D conversion output data is represented by the linear equation of i by knowing each value between two points.

By converting this characteristic linear equation into a relational equation of an analog input value with respect to A / D conversion output data, CP
The magnitude of the analog input value at that time can be calculated from the magnitude of the A / D converted digital value captured by U28.

Converting equation 24 into an analog input value for A / D conversion output data

[0226]

(Equation 29)

It can be expressed as

FIG. 57 is a flow chart of the analog input automatic correction. First, an analog input mode item to be set is selected by switching with an analog setting mode changeover switch. Next, a reference analog value is input (the reference analog value is stored in advance in the CPU 28 or the operator can freely set the analog value using the operation unit 18), and A / D conversion is performed. Is displayed, the operator confirms the digital value, and stores it in the memory 31 by pressing the registration button. Similarly, another reference voltage is input, and the A / D converted digital value is stored in the memory 31.

As a result, a linear equation can be obtained, and correction suitable for each unit can be performed.

Next, FIG. 58 shows an example of an external view of a power receiving panel of the conventional system shown in FIG. 1, wherein 1 is a power receiving and distribution panel, 3 is a meter showing voltage and current, and 6 is a protection relay.

FIGS. 59A and 59B show an application example of the power supply monitoring and control unit according to the present invention. FIG. 59A shows an application example of an in-panel mounting type mounted inside a distribution board or the like, and FIG. An application example of the recessed type mounted on the panel is shown below.

FIG. 59 shows an example of a vertically long type. In general, a box or cubicle box (housing) is often of a vertically long type, which is convenient for mounting. However, as shown in FIG. 60, it is of a horizontally long type. Is also good.

FIG. 60 shows an in-panel mounting type having a mounting groove 310 and a fixing lever 311 which can be mounted on a DIN rail.

FIG. 61 is a perspective view showing an external view of the board-embedded type, but showing an example of a vertically long type in which the arrangement of the operation unit and the display unit is changed from the above-mentioned example.

FIG. 62 shows an example in which colors are classified by measurement system in order to make it easy to determine the operation and display. For example, as described above, the voltage, current, and harmonic current are related to the R, S, and T phases. However, the power and the power amount are related to the active power (amount) and the reactive power (amount). It is best if these operation keys and indicators are provided individually, but they often serve the same purpose because they hinder miniaturization and cost reduction. In this case, it is difficult to judge and the usability is poor. This example solves this.
A key 137a for displaying current, a key name and a unit display unit 215a are arranged in the same color as the R, S, and T display units 216. Similarly, at the voltage and the harmonic current, ie, 137b, and 215b, 137f, and 215
f is also arranged in the same color, while the power display key 137c and the name section 215c are arranged in the same color as the valid / invalid display section 217. Similarly, the power amount display key 137d and the name part 215d are also arranged in the same color.

FIG. 63 is a rear view of the above-described board-surface embedded type shown in FIG. The terminal block 218 is arranged on the back surface to improve workability of wiring. FIG. 64 shows the terminal block 218 removed, and 219 denotes a receiving-side terminal block fixed to the main device. The terminal block 218 is detachable with a fixing screw 320.

As described above, since the attachment / detachment is easy, when replacement such as a failure is required, the replacement can be performed without removing the connection wire from the terminal block, so that the maintainability is extremely excellent.

According to the above embodiment, (1) the measured values of the voltage and the current can be obtained as the effective values, so that the accuracy is improved.

(2) Operation is simple because it can be displayed by key operation corresponding to monitoring information.

(3) Since this is a basic transmission control procedure, it is possible to configure a highly versatile system.

(4) Since a plurality of pieces of monitoring control information can be calculated in a complex manner, various kinds of information can be obtained.

(5) Maintenance can be performed without removing the wiring by the detachable terminals, and the work efficiency is good.

There are the following effects.

According to the present invention, it is possible to know the usage rate of the transformer with respect to the rated capacity, and to replace the transformer with an appropriate capacity in accordance with the usage rate, thereby saving power and extending the life of the distribution system. Power monitoring and control system that can

[Brief description of the drawings]

FIG. 1 is a connection diagram showing a power distribution system. FIG. 1A is a diagram illustrating a conventional system example, and FIG. 1B is a diagram illustrating a system example according to an embodiment of the present invention.

FIG. 2 is a block diagram of a power supply monitoring unit of the power supply monitoring and control device according to one embodiment of the present invention.

FIG. 3 is a block diagram illustrating a connection example of a system of a power supply monitoring and control device according to an embodiment of the present invention.

FIG. 4 is a perspective view showing an appearance of a converter of the power supply monitoring and controlling apparatus according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a master station of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 6 is a block diagram of a repeater of the power supply monitoring and control device according to one embodiment of the present invention.

FIG. 7 is a front view of an external appearance of a power monitoring and control unit of the power monitoring and control device according to one embodiment of the present invention.

FIG. 8 is a functional block diagram of a power supply monitoring and control device according to an embodiment of the present invention.

FIG. 9 is an address map showing an example of device addresses of the power supply monitoring and control device according to the embodiment of the present invention.

FIG. 10 shows a communication procedure of the power supply monitoring and control apparatus in one embodiment of the present invention. FIG. 10A shows a procedure at the time of normal operation, FIG. 10B shows a procedure at the time of a command error, and FIG. It is a figure which shows the procedure at the time of a communication error, respectively.

11A and 11B show transmission / reception messages of the power monitoring and control apparatus according to an embodiment of the present invention. FIG. 11A shows the configuration of a reception message, FIG. 11B shows the configuration of a transmission message, and FIG. It is a figure which shows the content of each.

FIG. 12 is a diagram showing an example of the contents of a command of the power supply monitoring and control device according to an embodiment of the present invention.

FIG. 13 is a connection diagram of a plurality of power monitoring and control units of the power monitoring and control device according to one embodiment of the present invention.

FIG. 14 is a flowchart of the terminating resistance control of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 15 is a transmission control flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 16 is an internal block diagram of a power monitoring and control unit of the power monitoring and control device according to one embodiment of the present invention.

FIG. 17 is an internal block diagram of a power monitoring and control unit of the power monitoring and controlling apparatus according to one embodiment of the present invention.

FIG. 18 is an internal block diagram of a power monitoring and control unit of the power monitoring and control device according to one embodiment of the present invention.

FIG. 19 is an internal block diagram of a power monitoring and control unit of the power monitoring and control device according to one embodiment of the present invention.

FIG. 20 is a flowchart of the entire control of the power supply monitoring and control unit of the power supply monitoring and control device according to one embodiment of the present invention.

FIG. 21 is a flowchart of a communication module of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 22 is a flowchart of a display module of the power monitoring and control apparatus according to one embodiment of the present invention.

FIG. 23 is a flowchart of a setting module of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 24 is a flowchart of a measurement module of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 25 is a flowchart of a check module of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 26 is a flowchart of a timer interruption process of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 27 is a flowchart of an interrupt from a transmission circuit of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 28 is a diagram of a communication state matrix of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 29 is a diagram of a communication state matrix of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 30 is a circuit diagram of a current measuring circuit of the power supply monitoring and controlling apparatus according to one embodiment of the present invention.

FIG. 31 is a flowchart of a current measurement of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 32 is a circuit diagram of a voltage measurement circuit of the power supply monitoring and control device according to one embodiment of the present invention.

FIG. 33 is a voltage measurement flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 34 is a circuit diagram of a ground fault current measurement circuit of the power supply monitoring and control device according to one embodiment of the present invention.

FIG. 35 is a flowchart of a ground fault current measurement of the power supply monitoring and control apparatus in one embodiment of the present invention.

36A and 36B show the configuration and operation of a voltage zero-cross circuit and a current zero-cross circuit of the power supply monitoring and control device according to one embodiment of the present invention. FIG. 36A is a circuit diagram, and FIG.

FIG. 37 is a flowchart of a cycle measurement of the power supply monitoring and controlling apparatus according to an embodiment of the present invention.

FIG. 38 is a frequency measurement flowchart of the power supply monitoring and controlling apparatus in one embodiment of the present invention.

FIG. 39 is a time difference measurement flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 40 is a phase difference measurement flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 41 is a circuit diagram of a harmonic current measuring circuit of the power supply monitoring and controlling apparatus according to one embodiment of the present invention.

FIG. 42 is a characteristic diagram illustrating a harmonic transmission filter characteristic of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 43 is a flowchart for measuring the active power and the reactive power of the power supply monitoring and controlling apparatus in one embodiment of the present invention.

FIG. 44 is a usage rate measurement flowchart of the power supply monitoring and control apparatus in one embodiment of the present invention.

FIG. 45 is a power amount measurement flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 46 is a flowchart of calculating a power amount charge of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 47 is a front view showing a display example of measured values of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 48 is a diagram illustrating an example of an operation of switching display units of R, S, and T phases of the power supply monitoring and control apparatus according to an embodiment of the present invention.

FIG. 49 is a diagram showing key inputs and display contents of the power monitoring and control apparatus according to one embodiment of the present invention.

FIG. 50 is a front view showing a display example of monitored values of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 51 is a front view showing a state display of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 52 is a front view showing a configuration of an operation unit of the power supply monitoring and control apparatus according to the embodiment of the present invention.

FIG. 53 is a front view showing a monitor input key of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 54 is a front view showing a terminal arrangement of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 55 is a circuit diagram of a current measuring circuit of the power supply monitoring and controlling apparatus in one embodiment of the present invention.

FIG. 56 is a characteristic diagram illustrating semi-automatic correction of an analog input of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 57 is a flowchart of automatic analog input correction of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 58 is a perspective view showing the appearance of a power distribution board of a conventional system of the power supply monitoring and control device in one embodiment of the present invention.

59 is a perspective view showing an application example of the power supply monitoring and control unit of the power supply monitoring and control device according to one embodiment of the present invention, wherein FIG. 59 (a) shows an in-panel mounting type and FIG. FIG.

FIG. 60 is a perspective view showing an external appearance of an in-panel type of a power supply monitoring and control device according to an embodiment of the present invention.

FIG. 61 is a perspective view showing an external appearance of a buried-in-panel type of a power supply monitoring and control device according to an embodiment of the present invention.

FIG. 62 is a front view showing a color-coded example of an operation unit and a display unit of the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 63 is a perspective view showing a back surface of a buried-in-panel type of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 64 is a perspective view showing a state in which the terminal block of the power supply monitoring and control device in one embodiment of the present invention is removed.

FIG. 65 is a flowchart of harmonic measurement by the power supply monitoring and control apparatus according to one embodiment of the present invention.

FIG. 66 is a temperature measurement flowchart of the power supply monitoring and control device in one embodiment of the present invention.

FIG. 67 is a power factor measurement flowchart of the power supply monitoring and control apparatus in one embodiment of the present invention.

FIG. 68 is an apparent power accumulation flowchart of the power supply monitoring and control apparatus in one embodiment of the present invention.

FIG. 69 is a flowchart illustrating a load factor measurement of the power supply monitoring and control apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1: Power distribution board, 2: Transformer, 4: Zero-phase current transformer, 5: Transformer, 7: Current transformer, 8: Pulse integrated watt hour meter, 9: Circuit breaker, 10: Power supply monitoring and control unit , 11: contact signal, 12: master station, 13: transmission line, 14: sensor, 15:
Power line, 16: transmission interface, 17: display unit, 1
8: operation unit, 19: alarm contact, 20: device address setting unit, 21: transmission speed setting unit, 22: secondary current transformer, 23:
Secondary transformer, 24: analog interface circuit, 2
5: temperature measurement interface, 26: pulse interface, 27: power supply unit, 28: central processing unit, 29: driver, 30: key buffer, 31: storage unit, 32: alarm contact driver, 33: buffer, 34: Internal bus.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor ▲ Taka ▼ Naohiro Kamo 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Pref. Nakajo Plant, Hitachi, Ltd. (72) Inventor Yasuyuki Hiyama Naka-Kitabara, Niigata 46-1 Tomioka, Jomachi-cho, Nakajo Plant, Hitachi, Ltd. (72) Inventor Matsuichiro Takahashi 4-chome, Kanda-surugadai, Chiyoda-ku, Tokyo Hitachi Techno Engineering Co., Ltd. 110953 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02J 13/00-13/00 311

Claims (2)

(57) [Claims] 1. An input unit for inputting information on voltage and current of a distribution system including a transformer, an analog interface circuit connected to the input unit for performing effective value conversion and digital conversion of an analog signal, and an analog interface A central processing unit connected to the circuit, an operation unit connected to the central processing unit for selecting information to be displayed, and an information unit connected to the central processing unit and displaying information selected by the operation unit Power supply monitoring system having a display unit for performing the operation and a transmission interface unit connected to the central processing unit.
Control device and transmission connected to the transmission interface
The information selected by the operation unit via the line
A central monitoring and control device for transmitting the
The equipment must be pre-installed with the transformer connected to the distribution system.
Power actually used for the specified rated power capacity and
Is configured to store the utilization calculated from the ratio of
The display section displays the usage rate by selecting the operation section.
The central monitoring and control device is configured to
Read the usage rate stored in the power monitoring and control device.
A power supply monitoring and control system characterized in that the power supply monitoring and control system is configured to be able to output . 2. The power supply monitoring and control system according to claim 1, wherein
Thus, the power monitoring and control device and the central monitoring and control device
And a repeater interposed therebetween, wherein the repeater has a pair of
Transmission line connection terminal, one pair of driver / receiver, one pair
Polarity detection circuit and time for one word length of transmission signal
Divider circuit and polarity detection after the time of one word length
A reset circuit for initializing the circuit.
One of the driver / receiver is connected to the pair of transmission line connection terminals.
Connected to one side and the pair of driver / receiver
The other end of the bus is connected to the other end of the pair of transmission line connection terminals.
The pair of polarity detection circuits is connected to the pair of driver / lasers.
Shaping of transmission waveform by connecting anti-parallel between the sheavers
Power supply monitoring configured to perform power and amplification
Control system.