JP2002199466A - Transmission terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission terminal that can easily measure each electric power of the respective branches of a distribution system. SOLUTION: The transmission terminal 1 installed at an installation site of an electric line to be monitored consists of a selector 17, that selects the current signal of two or more electric lines to be monitored in prescribed timing, an analog/digital converter 19 that converts the selected current signal into a digital quantity, a storage means 26 that stores the digital quantity converted from the current signal, a rated value setting section 22 that sets a rated value corresponding to each of the electric lines to be monitored, a central processing unit 8 that makes arithmetic operations of the stored contents, on the basis of the contents set by the rated value setting section 22, a transmission section 24 that communicates as for the arithmetic operation results with a host device and an enclosure that integrally accommodates the terminal components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission terminal device for measuring various electric quantities of a distribution system on site and transmitting the measured electric quantities to a centrally installed higher-level device. The present invention relates to a transmission terminal device suitable for measuring and transmitting to a higher-level device.

[0002]

2. Description of the Related Art Measurement and monitoring of various amounts of electricity in a power distribution system in a factory or a building are necessary for stable supply of power and for grasping load conditions. For example, Japanese Patent Application Laid-Open No. 60-186007 describes a conventional technique for monitoring a transformer, and Japanese Utility Model Application Laid-Open No. 61-14854 discloses a conventional technique for monitoring the maximum power demand. Has been described.

[0003] Such equipment and devices for measuring and monitoring the power receiving and distribution system have high investment costs, and therefore are limited to places where the objects to be measured and monitored are important, as in the prior art. For example,
When measuring and monitoring the distribution system branch section, if there are five branch circuits, measure and monitor only the important branch circuits among them, instead of measuring and monitoring all five of them. ing. Because the amount of electricity differs for each branch circuit, the meter transformer (CT), the meter transformer (VT), and the transducer for signal conversion attached to the branch circuit must be rated for the mounting location. This is because there is a problem that it must be used.

[0004] Further, when calculating the quantity of electricity from the measured data, it is necessary to perform calculation in accordance with the rating of the measuring instrument. Therefore, data taken in from different locations by instruments having different ratings are collectively collected by a central computer. There is a problem that it is not easy to perform calculations. Conventionally, for example, when measuring and monitoring the amount of electricity for two important branch circuits out of five branch circuits, a dedicated measurement / monitoring device (controller) is installed for each branch circuit. I have.

[0005]

In recent years, more and more energy saving has been required, and fine measurement and monitoring have been required. That is, in the above example, if there are five branches, it is necessary to measure and monitor all five branch electric circuits. However, when performing such detailed measurement and monitoring, if measurement and monitoring are performed by extending the conventional concept, it becomes necessary to install a transducer and controller for each branch circuit, and equipment costs become enormous. There is a problem that is not the target. That is: 1) It is necessary to select a transducer according to the rating of CT or VT for each branch, and it is not easy to determine the specifications.

2) The controller or the central unit needs to perform calculation processing in accordance with the CT for each branch, which is complicated.

[0007] 3) When the specifications of the CT change, it is necessary to change the transducer and the calculation process of the controller or the central unit.

[0010] 4) The number of man-hours for wiring the transducer, A / D converter, etc., is large.

5) The installation area is large when the transducers and the like are gathered.

6) The investment cost is large.

There is a problem that

SUMMARY OF THE INVENTION An object of the present invention is to solve all of the above-mentioned problems and to make it possible to easily perform detailed measurement and monitoring of a branch portion of a power distribution system, that is, a transmission terminal device which is most required in a branch portion. It is an object of the present invention to provide a transmission terminal device capable of realizing measurement of “voltage”, “power”, and “power amount” with one small device mainly by measuring “current” for each branch.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmission terminal device installed at a site where a monitored circuit is installed by transmitting a current signal of at least two sets of monitored circuits and a voltage signal of the monitored circuit at a predetermined timing. Selecting means for selecting, analog / digital converting means for converting the selected current signal and voltage signal into digital quantity, storing means for storing the converted digital quantity, and corresponding to the voltage and current of the monitored circuit. Rating value setting means for setting the rated value, a central processing unit for calculating the electric quantity of the monitored electric circuit based on the rated value set by the rating value setting means for the stored digital quantity, and a higher-level device. This is achieved by a configuration in which transmission means for communicating the result of the calculation between them are housed integrally.

[0014]

The current values and the like of all the branch circuits are taken into one transmission terminal device having the above configuration, and the central processing unit calculates various amounts of electricity in accordance with the ratings of the respective current values and the like, and the calculation results are superordinated. Transmit to device. This eliminates the need to install transducers of different ratings on one branch circuit, calculates various quantities based on each rating by the transmission terminal equipment installed on site, and the upper-level equipment installed in the center uses various electrical equipment. There is no need to perform quantity calculations.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a transmission terminal apparatus according to a first embodiment of the present invention. The transmission terminal device 1 includes components and devices described below in a single housing and is configured as an integral unit. In the transmission terminal device 1, reference numeral 2 denotes a voltage input unit, reference numerals 2a, 2b, and 2c denote terminals for supplying power to the transmission terminal device 1, and reference numeral 3 denotes a unit that converts the supplied power to a voltage suitable for each unit described below. It is a power supply unit for supplying to each unit, and corresponds to an input voltage of 85 V to 264.
4 is a signal transformer, 5 is a comparator for converting an AC signal into a DC signal of a predetermined rectangular wave, and 16 is an IC for shaping the waveform. Reference numeral 7 denotes a signal line for transmitting the shaped rectangular wave signal, which is a frequency detection signal line.

Reference numeral 8 denotes a central processing unit (hereinafter referred to as a microcomputer).
Called CPU. ), And each unit is collectively controlled with a main purpose of calculating current signals of two or more sets of monitored electric circuits. Reference numeral 9 denotes an R which stores the above-described arithmetic processing and overall control procedures.
OM (read-on memory), 10 is a RAM (random access memory) for storing the calculation results and the progress of the operation,
These ROM 9 and RAM 10 are built in the CPU 8.

Each of 11a, 11b,..., 11n is a current input section for receiving a current signal from one set of monitored electric circuits.
4 terminals 2a, 12b, 12c, 12d, internal current transformer 13, amplifier 14, and sample hold (hold)
It is composed of a circuit 15. Reference numeral 6 denotes a holding command signal line for giving an instruction to the sample and hold circuit 15, and reference numeral 17 denotes a selection unit (multiplexer) for selectively selecting signals from the plurality of input units at a predetermined timing. Is indicated by the control line 18.

Reference numeral 19 denotes an A / D converter (A / D converter) for converting the signal (analog signal) selected by the selector 17 into a digital value (value). 20, 21
Is a control line for giving a conversion instruction to the A / D converter 19 and detecting the end of conversion. 22b, 22c, ..., 2
2n is a setting unit provided corresponding to the CT 105a,.
This is to set the primary rating of CT. Also, 22a
Is a setting unit for setting the primary rating of the VT.

Reference numeral 23 denotes an address setting unit for setting a unique address of the transmission terminal device 1. When performing communication with a higher-level device installed in a central control room or the like, a plurality of addresses 23 are connected to the higher-level device. Is assigned to each of the transmission terminal devices. Reference numeral 24 denotes a transmission unit that communicates with a higher-level device.
5 connects to a higher-level device via a transmission line described later.
Reference numeral 27 denotes an amplifier of the same type as the amplifier 14 described above, for amplifying a voltage signal.

FIG. 2 is a configuration diagram of a system in which the transmission terminal device 1 shown in FIG. 1 is applied to a distribution system. 102 is a transformer (TR), 103 is a fuse (F) 104 is an instrument transformer (VT) 105a to 105e are instrument current transformers (C
T). 106 is a transformer (T) such as a secondary substation.
R), 107a to 107e are CTs. Reference numeral 108 denotes various loads such as a motor, a lighting device, a computer, and an air conditioner.

Reference numeral 100 denotes a central unit, which is a computer (general-purpose personal computer or the like) for totalizing and monitoring the results measured and calculated by a plurality of transmission terminal devices 1 installed at each site. 10
Reference numeral 1 denotes a transmission line that connects each transmission terminal device 1 and the central device 100.

FIG. 3 is a detailed actual connection diagram of the monitored circuit of the distribution system and the transmission terminal device 1 shown in the single line diagram of FIG. The solid connection diagram of FIG. 3 shows a three-phase three-wire system among various phase-wire systems, and is the most general one in a distribution system. In the figure, R, S, and T indicate phases of the distribution line. For easy understanding, R indicates the R phase, S indicates the S phase, and T indicates the T phase. Therefore, such a phase-wire type current measurement / monitoring requires at least two locations for one branch, and CTs are shown as 105aR, 105aT, etc. in the figure. The same applies to the single-phase three-wire system.

FIG. 4 shows the setting sections 22a and 22 in FIG.
The detailed circuit of 2b-22n and the correspondence of the setting part to the primary rating of VT and CT are shown. 220 and 221 are resistors for establishing a potential.

FIG. 5 is a front view of the transmission terminal device 1.
Parts indicated by reference numerals correspond to FIG. Terminal 2
a to 2c, 12a to 12d, 25 and each setting unit can be covered with covers 223, 224.

Next, the operation of the transmission terminal device 1 will be described. FIG. 6 shows a basic method of obtaining a measurement value by sampling (extracting) an AC signal at a predetermined timing, and in this embodiment, one cycle of AC is sampled 12 times.

The execution value I of the current is calculated by squaring each sampling value (i1 to i12), adding one cycle, and dividing by the number of samplings n (12), as shown in the formula shown in FIG. It can be calculated by taking the root. The same applies to the voltage. In this embodiment, the calculation result is obtained in one cycle after the sampling.

An example in which the number of branches in the branch portion is "8" will be described below. FIG. 7 is a flowchart illustrating a power-on processing procedure. First, in S1, internal initial processing is performed. In S2, a rectangular wave check of the frequency detection signal line 7 in FIG. 1 is performed to determine whether the frequency is 50 Hz or 60 Hz, and a sampling interval is determined based on the determination result. That is, 50
In Hz, one cycle is 1/50 second, so the sampling interval is 1 / (50 × 12) seconds.
(60 × 12) seconds.

The next step S3 is to take into consideration the case where the calculation processing shown in FIG. 6 has been completed earlier, and checks the next sampling start timing (for example, the rising edge of the rectangular wave). Then, in S4, the CPU 8 sets the sampling interval to
The internal timer is set so that interrupt processing can be performed at a predetermined timing. In the next step S5, the timer interrupt is released so that the above-described interrupt processing can be performed, and the process waits for an interrupt.

FIG. 8 is a flowchart showing a timer interrupt processing procedure. The time of the interruption interval is the time of the sampling interval described above. First, in S6, a hold (hold) command is issued via the hold command signal line 6, and the process proceeds to S7. In S7, first, in S7a, the selection unit 1
7 is selected (in this case, R
Next, in S7b, a conversion command is issued to the A / D conversion unit 19. Next, in S7c, it is determined whether or not the conversion has been completed. If the conversion has not been completed, the process waits for the completion.
Is read and stored in the RAM 10. The storage location will be described later with reference to FIG.

Next, in S8, the second channel of the selector 17 is selected (corresponding to the voltage between the S phase and the T phase of the monitored electric circuit in this case), and the same processing as in S7 is performed. In the next S9, the third channel of the selector 17 is selected (corresponding to the R phase of the CT of the monitored electric circuit in this case), and the same processing as the above S7 is performed. In S10, the fourth channel of the selection unit 17 is selected (in this case, it corresponds to the T phase of CT of the monitored circuit), and
The same processing is performed. Hereinafter, similarly, the processing is successively performed up to the 18th channel corresponding to the CT of the monitored electric circuit of the other branch portion. This series of processing is performed by v1, i1 shown in FIG.
Is the timing corresponding to the position.

In S12, it is checked whether or not the number of samplings for one cycle of the AC described above, that is, in this embodiment, whether or not twelve has been completed. If not, the flow proceeds to S13 to update the storage location. In S14, the reception interrupt described later is released, and the next sampling timing (ie, v in FIG. 6)
Wait for an interrupt at (2, i2).

When a series of processes of 12 times in one cycle is completed in this way, the process proceeds to S15 to inhibit the timer interrupt (that is, the sampling process). In S16, the reception interrupt is released, and the process proceeds to S17. The calculation process will be described later with reference to FIG. Next, when the calculation process is completed, the process proceeds to S18, where a timing check is performed in the same manner as in S3, the timer interrupt is released in S19, and a standby state, that is, an interrupt wait state is set.

FIG. 9 is a flowchart showing a reception interrupt processing procedure. This process is a process for performing communication with the host device 100. The reception interrupt has a lower priority than the timer interrupt process described with reference to FIG. 8, and the process is performed when the reception interrupt is released.

First, the content received in S40 is checked for a communication failure, then the head address of the data to be transmitted (the calculation result shown in FIG. 12) is set in S41, and the transmission is possible in S42. If it is possible to transmit, data is read from the location indicated by the above address in S43 and transmitted in S44. In the next S45, it is checked whether or not all the data has been transmitted. If not, the data address is updated in S46 and the process returns to S42. When the transmission of all data is completed, the process returns to the original processing, that is, the place in the standby state. Alternatively, the process returns to the middle of the calculation process in S17 and continues.

FIG. 10 is a flowchart showing the calculation processing procedure in the three-phase three-wire system and the single-phase three-wire system. FIG.
FIG. 9 is a diagram showing that sampling is performed at the predetermined timing described in FIGS. 6 and 8, converted into a digital amount by the A / D converter 17, and stored in the readable / writable RAM 10. FIG. 12 is a diagram illustrating an example in which the result of the calculation process illustrated in FIG. 10 is stored.

First, the line voltage between the R phase and the S phase is calculated in S30 from the sampled data shown in FIG. 11, and the calculation is basically performed as shown in FIG. Then S
At S31, the line voltage between the S phase and the T phase is similarly obtained, and at S32, the line voltage between the T phase and the R phase is calculated. The line voltage between the T phase and the R phase in the three-phase three-wire system and the single-phase three-wire system is 0.
It is known that it can be obtained by subtracting from.

Next, in S33, the input unit 11 shown in FIG.
Calculation is performed on the current corresponding to a. That is, the current of the R phase is calculated by S33a, the current of the T phase is calculated by S33b, and the result is obtained by subtracting the S phase from 0 as shown in S33c, similarly to the above voltage. In S34, the calculation is performed on the current corresponding to the input unit 11b shown in FIG. 1, but this is the same as S33.

As described above, the current is calculated one after another. In the present embodiment, the current is calculated for eight sets, and the result is stored in each storage area of the RAM 10 as shown in FIG.

Although the above embodiment has been described including the calculation of one set of voltages, this calculation can be omitted. Also, in the flowchart shown in FIG.
Although the conversion calculation for the primary ratings of VT and CT shown in FIG. 4 and the detailed description of the resolution of the amplifiers 14 and 27 and the A / D converter shown in FIG. 1 are omitted, the calculation is collectively performed after the calculation for obtaining the respective roots. Obviously you can.

According to the above-described embodiment, measurement and monitoring can be performed on a plurality of currents and voltages at branch portions in the three-phase three-wire system and the single-phase three-wire system.

Next, an application example of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 13 is a diagram in which the above-described transmission terminal device 1 is connected to a single-phase two-wire system. In this embodiment, the power supply terminals 2b and 2c are short-circuited at the terminals, and the voltage between the S phase and the T phase described above becomes "0". FIG. 14 shows a calculation flowchart of the single-phase two-wire system, and the calculation is performed based on the sampling data shown in FIG. The calculation processing in FIG. 14 differs from the above-described first embodiment in that the voltage calculation is for one phase (between R and S) and the current calculation is not for the S phase. FIG. 15 shows a storage example of the calculation result.

That is, in this embodiment, extra calculations are omitted from the three-phase three-wire system and the single-phase three-wire system. However, from the opposite viewpoint, the calculation process of the first embodiment can be used as it is. This indicates that there is no problem.

In the first embodiment, the current measurement with the number of branches of eight in the three-phase three-wire system and the single-phase three-wire system has been described. In the present embodiment, the number of branches in the single-phase two-wire system depends on the application. This means that 16 current measurements are possible.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. An object of the second embodiment is to enable the measurement of the current, the electric power, and the electric energy of two or more sets of monitored electric circuits in the branch portion.
The description of the three-phase three-wire current measurement and the single-phase three-wire current measurement is omitted because it has been described in the first embodiment, and the measurement of electric power and electric energy will be described below.

FIG. 16 shows the power for a single phase, and it is known that the average of the product of the current and the voltage in one AC cycle (ΔP in the figure) is defined as the power. It is. Therefore, the product obtained by adding the product of the sampled current i and voltage v at each predetermined timing described in FIG. 6 for one cycle and dividing by the number of times of sampling is the power. The electric energy is obtained by multiplying electric power by time, multiplying ΔP and Δt shown in the figure, and accumulating the result to be an integrated electric energy.

Next, the calculation procedure will be described with reference to FIG. First, based on the voltage and current sampling data described with reference to FIG. 11, the power of the portion corresponding to the input unit 11a is calculated in S60. In S60a, the power between the R phase and the S phase is obtained. Next, in S60b, the power between the S phase and the T phase is obtained. In the next 60c, the power for one branch is obtained by the two-power meter method. Similarly, the other current input units 11b,.
11n (in this example, for eight branches), S61 and S6
Calculation is performed in the order of 2.

In S63, the electric energy is calculated. However, as described with reference to FIG. 6, since the calculation processing is exclusively used in the next cycle,
Multiply by "2" and accumulate and store the result. Such processing is sequentially performed in S64 and S65, and the result is stored in the RAM 10 as shown in FIG. Thereafter, the current calculation shown in FIG. 10 is performed. FIG. 18 is a diagram illustrating an example in which the calculation results of the power and the power amount are stored. In the figure (△ PRS),
(△ PST) indicates the power between the lines.

In this embodiment, the calculation of the electric energy is performed after the calculation of all the electric powers. However, it is obvious that the calculation may be performed immediately after the electric power of each part is calculated. In addition, although the calculation processing time shown in FIG. 6 is shown for one cycle, it goes without saying that if the calculation processing time is long, it may be extended to the next cycle and tripled.

Next, an application example of the second embodiment will be described with reference to FIG.
This will be described with reference to FIG. FIG. 19 is a flowchart showing calculation of electric power and electric energy in the single-phase two-wire system. S70 and S71 correspond to 105aR, 10A shown in FIG.
This is the step of calculating the power corresponding to 5 aT,
60a is the same as FIG. S71 (60b ')
Slightly different from S60b shown in FIG. 17, the voltage sampling data is different from S60a in that it is the same product of the voltage between R and S and the T-phase current as in S60a. Similarly, power calculation for 16 points is performed in the order of S72, S73, and S74. Then, the power amount is calculated in S75, and in S7
The calculation of the electric energy for 16 points is sequentially performed in steps S6 and S77.

The results of these calculations are stored at predetermined positions in the RAM 10 as shown in FIG. Here, "-" in the figure indicates an empty space, but this meaning should be understood by comparing with FIG. That is, the concept is unified with the three-phase three-wire system and the single-phase three-wire system. However, in the calculation processing procedure, since the voltage is different as described above, the ROM 9 storing the processing procedure is different.

In the description of FIG. 1, the description of the power failure detection unit 28 and the negative nonvolatile storage unit 26 is omitted, and the description will be made below. The power failure detection unit 28 operates upon receiving the output of the waveform shaping circuit 6. That is, the power failure is detected, the power failure is immediately transmitted to the CPU 8 via the power failure detection signal line 29, and the calculation result of the electric energy is stored in the nonvolatile storage unit 26.

The nonvolatile storage unit 26 stores, for example, EEPRO
M (Electrical / Erasable / Pro)
Grammable, Read, Only, Memmo
ry). This element is an electrically erasable and rewritable memory element that can be permanently stored.

When the power is restored, the contents of the non-volatile storage unit 26 are transferred to the position of the power amount calculation result in the RAM 10 in the initial processing of the power-on flowchart shown in FIG. It is possible to accumulate.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In the above-described second embodiment, the ROM 9 is dedicated to each of the three-phase three-wire system, the single-phase three-wire system, and the single-phase two-wire system because the power calculation processing is different. However, considering the standardization of products, Not preferred. Therefore, in the present embodiment, in order to solve this, a phase line type determination process shown in FIG. 21 is performed.

Therefore, the VT primary rating setting section 2 shown in FIG.
Using the bit No. 4 (222) of 2a, the CPU determines the phase line type and performs the calculation processing of the flowchart shown in FIG. That is, prior to the calculation processing, in S47, the single-phase 2
Wire type (bit No. 4 of the VT primary rating setting section is on)
It is determined whether or not it is not a single-phase two-wire system.
Calculate the electric power and electric energy of the wire system (same for the single-phase three-wire system)
In S49, calculation of voltage and current is further performed. If it is a single-phase two-wire system, the process proceeds from S47 to S50, where a single-phase two-wire power / power amount calculation is performed, and then a single-phase two-wire voltage / current calculation is performed. The contents of the calculation processing are as described in the first embodiment and the second embodiment. The calculation procedure is stored in the ROM 9.

As described above, the transmission terminal apparatus 1 can be used in accordance with the phase line type of the branching part by performing the phase line type determination. Therefore, the product is standardized, and the user does not have to select a model.

Although the electric quantity measurement in the second embodiment and the third embodiment is voltage / current and power / power amount, if there is sampling data of voltage / current, reactive power and reactive power The amount can be calculated. Although detailed description is omitted, it is a known fact that the reactive power is obtained by the product of the voltage and the current having a phase difference of 90 °. When the power (active power) and the reactive power are obtained, the power factor can of course be calculated.

[0058]

According to the present invention, the specification can be easily measured by one device without worrying about the CT primary rating and the VT primary rating for each branch portion in the power distribution system. Centralized monitoring becomes possible. In addition, since the transmission terminal device itself performs each calculation and transmits it to the higher-level device, the burden on the central device is reduced. Further, even if there is a change in CT or VT, the transmission terminal device can cope with the change. There is also an effect that there is no need to change the calculation process.

The effects of reducing the number of man-hours for wiring work and reducing the installation area are great. Further, the fact that the power and the amount of power for each branch of the branch portion can be measured enables detailed energy use state for each load to be grasped, which is useful for energy saving measures. Furthermore, since the phase line type can be determined, there is a great effect that the measurement according to the phase line type of the distribution system can be performed by one unit, which greatly reduces the investment cost and has a great effect on the stable supply of the distribution system. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission terminal apparatus according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram in which the transmission terminal device shown in FIG. 1 is arranged in a distribution system.

FIG. 3 is a substantial connection diagram in a three-phase three-wire system (the same applies to a single-phase three-wire system).

FIG. 4 is a detailed diagram of a setting unit for setting a primary rating of CT and VT, and a diagram showing contents of setting of the setting unit for the primary rating.

FIG. 5 is a front view of the transmission terminal device.

FIG. 6 is a diagram illustrating sampling and current / voltage calculation formulas.

FIG. 7 is a flowchart illustrating a processing procedure when power is turned on.

FIG. 8 is a flowchart illustrating a timer interrupt processing procedure.

FIG. 9 is a flowchart illustrating a reception interrupt processing procedure.

FIG. 10 is a flowchart illustrating a three-phase three-wire / single-phase three-wire calculation processing procedure;

FIG. 11 is a diagram illustrating a storage example of sampling data.

FIG. 12 is a diagram illustrating a storage example of a calculation result of a three-phase three-wire system / single-phase three-wire system.

FIG. 13 is a schematic diagram of a single-phase two-wire system.

FIG. 14 is a current calculation flowchart in a single-phase two-wire system.

FIG. 15 is a diagram illustrating a storage example of a single-phase two-wire calculation result.

FIG. 16 is a diagram illustrating power calculation.

FIG. 17 is a calculation flowchart of electric power and electric energy of a three-phase three-wire system (the same applies to a single-phase three-wire system).

FIG. 18 is a diagram illustrating a storage example of power / power amount calculation results.

FIG. 19 is a calculation flowchart of electric power and electric energy of a single-phase two-wire system.

20 is a diagram illustrating a storage example of the result of FIG. 19;

FIG. 21 is a flowchart for performing processing by determining a phase line type.

[Explanation of symbols]

1, transmission terminal device, 2: power supply terminal, 11a, 11b,
..., 11n; current signal input section, 17; selection section, 19;
/ D conversion unit, 8; central processing unit, 22a; VT primary rating setting unit, 22b, 22c, ..., 22n; CT primary rating setting unit, 24; transmission unit, 222;

Claims (1)

[Claims] 1. A selecting means for selecting, at a predetermined timing, current signals of two or more sets of monitored circuits and voltage signals of monitored circuits, and an analog / digital converter for converting the selected current signals and voltage signals into digital quantities. Digital conversion means; storage means for storing the converted digital quantity; rated value setting means for setting a rated value corresponding to the voltage and current of the monitored circuit; and rated value setting means for the stored digital quantity. A central processing unit that calculates the electric quantity of the monitored electric circuit based on the rated value set by the above, and a transmission unit that communicates the result of the calculation between the host device and the host device. Transmission terminal equipment.