KR101024628B1 - Electronic watt-hour meter - Google Patents

Abstract

PURPOSE: An electronic watt-hour meter for preventing fire by detecting a temperature is provided to generate a warning signal, display a warning signal on an LCD screen, or transmit a remote signal to an upper meter system to prevent a load or/and block an over current when an abnormal temperature is detected, thereby preventing fire in advance. CONSTITUTION: A current detecting unit(22) includes a power source circuit(11) and a power interruption compensation unit(12). The power source circuit supplies power to drive an electronic watt-hour meter. The power interruption compensation unit supplies backup power for storing data measured during power interruption. The current detecting unit detects currents of a power supply unit(10) and a power line. A voltage detecting unit(21) detects a phase voltage of the power line.

Description

Electronic watt-hour meter for fire prevention through temperature detection

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic watt-hour meter. In particular, the electronic wattmeter part may be overheated due to a contact failure occurring at a connection portion of the electronic wattmeter, and so on. The present invention relates to an electronic power meter having a function of detecting a temperature and generating an alarm signal in advance when it is out of the normal temperature range or transmitting a remote signal to a higher meter reading system.

In general, the electronic digital electricity meter (hereinafter referred to as an electronic electricity meter), which is widely used in the industry, is composed of various electric and electronic devices, converts analog data of voltage and current into digital data, calculates power using digital data, and calculates time. The amount of power is measured by accumulating the power change according to the flow.

In the process of converting voltage analog data into digital data, a voltage divider circuit using a resistor is used to step down several tens or hundreds of volts into several volts for digital conversion.

The process of converting current analog data into digital data is performed by converting a high current into a low current using a current transformer, converting it into a voltage using a resistor, and converting the signal into an analog / digital converter. Computing and digitally displaying such changed data is a common configuration of an electronic electricity meter.

In the electronic wattmeter, the electronic wattmeter is provided with a connection terminal or the like as shown in FIG. 1 in order to receive a voltage current flowing in a line. In addition, there are various types of electronic components for measuring and measuring the magnitude of a voltage and current, and current is always flowing through such components.

Due to the structural characteristics and electrical characteristics of the electronic electricity meter

When excessive temperature rise occurs in terminal block, terminal, and PCB, there is no means to detect the situation for this abnormal temperature, and thus it has been eventually led to fire due to accumulated heat stress.

Therefore, the present invention is to solve the problems of the prior art ,

Electric wires inside the meter connected to the metallic terminals (202, 203, 204) whose temperature rises due to the increase in contact resistance due to overcurrent flow, loosening or loosening of terminal screws, etc. (209, 213, 214) is equipped with a temperature detection sensor unit 39 on the surface of the alarm when the abnormal temperature is detected, the alarm signal generation or display on the LCD screen and send a remote signal to the upper meter reading system to cut off the load or the flow of over current Electronic electricity meters that can contribute to preventing fires in advance. To provide .

The object of the present invention,

In the electronic electricity meter,

  A power supply circuit 11 for supplying power for driving the electronic electricity meter;

A power supply unit 10 including a power failure compensator 12 for providing backup power for preserving data measured during a power failure; and

 A current detector 22 for detecting current of the power line and

A voltage detector 21 detecting a phase voltage of the power line;

Analog-to-digital converters 23 and 24 and the analog-to-digital converters connected to the current detector and the voltage detector to convert the detected current and the detected phase voltage detected by the current detector and the voltage detector into digital signals. A power measuring unit 20 connected to the units 23 and 24, the power measuring unit 20 including a measuring unit 25 for measuring the amount of power integrated with the digital signals of the detected current and the detected phase voltage;

Central processing unit (CPU) 31 and LED 32 for measuring error and oscillation circuit 33 and nonvolatile memory 34 and communication circuit 35 and power monitoring circuit 36 and display unit 37 and It consists of an operation switch unit 38, a temperature detection sensor unit 39 and a signal input / output circuit unit 40 to perform the functions of error correction, data transmission and reception, temperature measurement, indicator electronic power amount of the measurement data input from the power measurement unit. It can be achieved by providing an electronic electricity meter for fire protection through the temperature detection according to the invention, characterized in that it consists of a digital circuit unit 30 to control the entire system to be able to.

According to the invention Electronic electricity meter for fire prevention through temperature detection

The function of a thermometer is added to the watt-hour meter. If an overcurrent flows, the temperature rises due to heat generation, the temperature rises due to an increase in contact resistance caused by loosening of terminal screws, and the malfunction of internal electronic parts. When an abnormal temperature is detected, an alarm signal may be generated or displayed on the LCD screen, and a remote signal may be transmitted to a higher meter reading system to cut off the load and / or block the flow of overcurrent to prevent the occurrence of a fire in advance. There is.

1 is a block diagram of a conventional electronic electricity meter
2 is a state diagram in which an external wire is connected to the electronic wattmeter as in the present invention.
FIG. 3 is a connection diagram for the current path as shown in FIG.
4 is a practical example of a burnout caused by a fire due to a poor connection of a terminal block that is a current path of an electronic watt-hour meter.
5 is an electronic watt-hour meter equipped with a temperature detection sensor circuit according to the present invention.
6 is a state diagram in which the temperature detection sensor according to the present invention is attached to a terminal block that is a current path.
7 is a detailed configuration diagram of the signal input / output circuit unit.
8 is a flow chart of the electricity meter operation of the present invention.
FIG. 9 is a flowchart illustrating an operation of detecting and alarming a temperature detected by a temperature detection sensor of an electronic wattmeter of the present invention.

The object of the present invention and the constitution and effects of the present invention to achieve the same will be more clearly understood by the following description of the preferred embodiment of the present invention with reference to the accompanying drawings.

First, prior to the description of the present invention will be described with respect to the general configuration of the electronic electricity meter.

The operation of the electronic watt-hour meter and the configuration of the present invention are known and publicly known as disclosed in Japanese Patent Application Laid-Open No. 2006-300729, Korean Patent Publication No. 2009-0071092, and Korean Patent Publication No. 1993-0010558. The description will be omitted.

 One to help understanding of the present invention

The operation and configuration of the electronic power amount in the present invention will be briefly described.

1 is a block diagram of a conventional electronic electricity meter

2 is a state diagram in which an external wire is connected to the electronic wattmeter as in the present invention.

 Figure 3 is a connection diagram for the current path in the connection diagram as shown in FIG.

4 is a practical example of a burnout caused by a fire due to a poor connection of a terminal block that is a current path of an electronic watt-hour meter.

5 is an electronic watt hour meter equipped with a temperature detection sensor according to the present invention.

6 is a state in which the temperature detection sensor according to the present invention is attached to a terminal block that is a current path.

7 is a detailed configuration diagram of the signal input / output circuit unit.

8 is a flow chart of the electricity meter operation of the present invention.

FIG. 9 is a flowchart illustrating an operation of detecting and alarming a temperature detected by a temperature detection sensor of an electronic wattmeter of the present invention.

First, FIG. 1 is largely composed of three blocks.

The power supply circuit unit 10 includes a power supply circuit 11 and a power failure compensator 12. The commercial power supply side connects the commercial power supply to the input of the power supply circuit 11, and the output is an operation power supply for various electronic components constituting an electronic electricity meter. Supplied.

The power supply circuit unit 10 receives AC power from the power supply to rectify and converts the AC power into DC required by various electronic components inside the instrument. The power supply circuit 11 is a power transformer. DC voltage is generated by configuring a power supply or switching-mode power supply (SMPS) power supply circuit. The power failure compensator 12 generally uses a backup battery for power failure compensation as a power source used to maintain time information of the instrument during power failure.

The power measuring unit 20 includes a voltage signal detecting unit 21, a current signal detecting unit 22, a voltage A / D converting unit 24, a current A / D converting unit 23, and a measuring unit 25. The voltage signal detection unit 21 is connected in parallel with the power supply side 1S and 2S to receive an input, and the current signal detection unit 22 is connected in series with the power supply side 1S and its output is connected to the load side 1L. The voltage and current applied using these detectors are converted into minute voltage signals, and then applied to the voltage A / D converter 24 and the current A / D converter 23.

The analog signal is converted into a digital signal using the voltage A / D converter 24 and the current A / D converter 23. The converted digital signals corresponding to these voltages and currents are multiplyed by the measurement unit 25 to calculate the watts, and then a "watt" value or a signal proportional to the power is calculated. Frequency "and applies it to the central processing unit (CPU) 31 of the digital circuit unit 20.

The digital circuit unit 30 includes a central processing unit (CPU) 31, an error measuring LED 32, an oscillation circuit 33, a nonvolatile memory 34, a communication circuit 35, and a power monitoring circuit 36. It is composed.

The central processing unit (CPU) 31 of the digital circuit unit 30 continuously accumulates the " watt " value, which is the raw data output from the power measuring unit 20, or a signal proportional to power, and accumulates the " frequency " signal. To calculate the amount of power (kWh). In the case of calculating the amount of power using the frequency signal, the amount of power used becomes 1 kWh when the frequency signal is continuously counted and the number of pulses equal to the instrument constant is input. Error measuring LED 32 is used to measure the accuracy (accuracy) by the pulse output from the CPU in proportion to the power consumption used in the load. The oscillation circuit 33 is used as an oscillator necessary for the CPU 31 to operate, and is connected to the crystal terminal of the CPU. The nonvolatile memory 34 is a nonvolatile memory for storing data calculated and calculated by the CPU. The communication circuit 35 is connected to an external computer to read data of the meter or input parameters required for the operation of the meter. Optical communication interface and / or modem interface circuit for remote meter reading.

The power monitoring circuit 36 monitors the state of the AC power and switches the power to operate the meter when the input AC power falls below a predetermined setting level. mode to extend the life of the backup battery.

The data display unit 37 is constituted by a display device conventionally used in the art such as an LCD 37 so as to display weighing data to an electric user.

Figure 2 shows the wiring diagram of the electricity meter terminal and the external wire when the electricity meter 100 is used directly in the field. The electricity supplied from the power utility company is supplied on the supply side wires L and N are two current terminals 202 and 203 disposed inside the terminal block 201 of the electricity meter. It is inserted into the wire insertion hole 212 of the and then firmly fixed with two wire fixing screws (205, 206) provided in each terminal. In addition, the left side of the electricity meter internal current line 209 is fixed to the upper end of the current terminal 202 by using the internal terminal screw 210, the right side of the internal current line 209 is a current terminal using the terminal screw 211 It is fixed with the upper end of 204 to form a passage of current flow.

Of the two load-side wires, the neutral wire is inserted into the wire insertion hole of the current terminal 203, and the live wire on the load side is inserted into the wire insertion hole of the current terminal 204, and two fixing terminal screws 207 and 208 are respectively placed. It is firmly fixed using), and the electric energy supplied from the power supply side is passed through the electricity meter to the load side and the amount of power used by the load is measured and measured.

FIG. 3 is a detailed wiring diagram of the current path of FIG. 2, in which the meter case is removed and only the portion of the conductor through which the current flows. Description of the technical configuration is the same as the description of FIG. 2 described above, and will be omitted.

4 shows that an overcurrent of a capacity that the meter can allow flows for a long time in the current circuit of the electronic wattmeter, or the terminal screw 205 fastened to the current terminal 202 is pulled out due to vibration accumulated for a long time. In this case, the contact resistance between the external wire and the current terminal 202 is increased, and thus, only part of the electricity meter is burned out without being completely burned down as a result of accumulated heat generation.

The internal circuits of the electricity meter are all burned out, leaving only part of the case, terminals, and external wires.

Conventional electronic wattmeter is used in the field of validity of verification (usually 10 years) after installation on the field by law on metrology. During this period, if external vibration is continuously applied to wattmeter, terminal screw Loosening or loosening occurs.

As a result of fire and burnout accidents caused by an increase in contact resistance, and also when the electric load uses continuous overcurrent above the meter's rating, the temperature of the terminal block rises, which is caused by plastic In the event of a melted meter case material, the adjacent conductors short-circuit with each other, causing fire accidents.

Another configuration of the present invention shown in FIG. 5 is a configuration different from the electronic wattmeter shown in the related art of FIG. 1 except for the temperature detection sensor unit 39, the operation switch unit 38, and the signal input / output circuit unit 40. It can be seen that the configuration is the same.

The same components as those of the conventional configuration are not only general and well-known components of the electronic watt-hour meter but have been described in the above-described conventional technical descriptions, and thus, detailed descriptions thereof are omitted. I will explain.

The temperature detecting sensor unit 39 is a temperature detecting circuit attached to a terminal and an electric wire through which current flows to detect an abnormal temperature caused by an overcurrent flow or contact resistance to prevent a fire from occurring. Resistive temperature sensors, thermocouples, etc. are commonly used in this field.

Circuits for converting the thermometer readings of the analog values measured by these sensors to digital to be suitable for the central processing unit are known in the art as known in Korean Patent Registration No. 10-0202694, Korean Patent Publication No. 1997-0001964, and the like. Since a common temperature measuring circuit is utilized, a detailed description thereof will be omitted.

That is, the temperature detection sensor unit 39 attached to the current terminal is configured to detect the surface temperature and transmit it to the central processing unit 31. In the present invention, for the convenience of description, the temperature detection sensor unit 39 is mounted on the current terminal, etc., but it will be apparent that the electronic power meter may be mounted on any component capable of generating heat by electric current. Representative components may be terminal blocks connected with wires, wire parts connected to terminal terminals, and the like. It can also be installed internally to detect the internal temperature of the electronic meter.

The signal input / output circuit unit 40 is a circuit unit that transmits an alarm signal to a modem or an upper meter reading system when an abnormal temperature is detected, and when the external system is connected to another system as shown in FIG. A photo isolator IC1 was used for electric isolation, and the anode (IC1_1) of the input diode of the photo coupler was connected to VCC, and the cathode (IC1_2) was a resistor for current limiting. One end of R1) is connected in series, and the other side is connected to the input / output (I / O) terminal for the abnormal temperature output (emergency-temp) of the central processing unit, and also the collector (IC1_4) of the phototransistor output terminal of the photocoupler. A surge protection device, such as a metal oxide varistor (TNR1), is connected between the and emitter IC1_3 to protect against surge inflow.

Looking at its operation, when the temperature is not high, CPU_I / O, which is the emergency_temp output of the CPU, maintains the logic "H" state. At this time, the input diode of IC1 is turned OFF because no current flows, and eventually the phototransistor output of IC1 outputs an "OFF" state.

On the other hand, when an abnormal temperature is detected by the temperature detection sensor, the CPU_I / O, which is the emergency_temp output of the CPU, is changed to the logic "L" state by the firmware program operation. Accordingly, the cathode of the input diode of IC1 (IC1_2) Since the potential of is in the logic "L" state, current flows (conducts), and eventually the phototransistor output of IC1 outputs an "ON" signal.

The external modem or / and the external system or / and the upper remote metering server monitors this status, and when it is turned “ON”, recognizes that the electronic meter is in an abnormal high temperature state and visits the site where the meter is installed in case of fire and takes necessary measures. It will be done. The output signal of the signal input and output circuit unit 40 may be utilized as an operation signal such as a circuit breaker if necessary.

The operation switch unit 38 is for inputting various parameters required for operating the date, time, and other electronic wattmeters, and is a switch used for setting or changing data in the microcomputer in the field such as a button switch.

In the electronic wattmeter of the present invention configured as described above, as shown in FIG. 6, a temperature detecting sensor part 39 such as a thermocouple is attached to the current terminals 202, 204, 206 or a wire part connected to the current terminal, although not shown, and the temperature is measured. The temperature measurement detected by the detection sensor unit 39 is input to the central processing unit.

 Hereinafter, a process of generating an alarm according to a corresponding temperature by measuring a temperature at a current terminal or the like in the electronic wattmeter of the present invention will be described in detail with reference to FIGS. 8 to 9.

8 is a flow chart of the electronic electricity meter of the present invention " starts " when power is supplied to the instrument.

In the "initialization" routine, the input and output ports are designated as inputs or outputs in order to obtain the desired operation, and the electronic components included in the circuit configuration are set as initial operating conditions for normal operation.

The main routine includes timers for interrupt generation and time generation, power calculation, time and date generation, content display, key (switch) operation, power off and input subroutines, and data storage subroutines. As long as power is supplied to the electricity meter, it is executed repeatedly.

The electric power amount calculation subroutine calculates the electric power and electric power used by the load side with the output value of the measuring unit 25, and also calculates the instantaneous values of the current, voltage, voltage current phase angle and frequency which are currently flowing.

The time and date generation subroutines are subroutines that create the seconds, minutes, hours, and dates required for operation in the meter.

The content display subroutine is a subroutine for displaying the weighing data on the LCD, etc., and the key (switch) operation subroutine is for setting and changing data or parameters necessary for the operation of the electricity meter according to the key operation. and change), and the data storage subroutine is a subroutine that periodically stores metering data in nonvolatile memory in preparation for power failure.

The above-described subroutines for measuring electricity are well-known western routines commonly used in electronic electricity meters produced and marketed by the applicant of the present invention, and thus detailed descriptions such as flowcharts are omitted.

The temperature detection and abnormal temperature alarm subroutine is a subroutine for carrying out the object of the present invention and periodically compares the temperature detected by the temperature detection sensor with an over temperature threshold limit value set to generate an abnormal temperature alarm. If the detected temperature exceeds the set reference temperature, alarm signal is generated and / or displayed on the LCD screen and / or the power supply is cut off and / or transmitted to the upper meter reading system before the fire occurs. It is a subroutine that can recognize abnormal temperature situation and take precautionary measures against fire.

9 is a flowchart of the temperature detection and abnormal temperature alarm subroutines.

In order to measure the temperature generated at the current terminal and the like after the operation of the electronic watt-hour meter in the unit of a certain cycle, the central processing unit caused the interrupt to occur 391 every certain period (eg, 100 msec, 500 msec, 1 sec, 2 sec, etc.).

When this interrupt occurs, the A / D converter is driven 392 to obtain the current temperature value from the temperature detection sensor unit 39 through the A / D converter.

By comparing the current temperature value T1 with the set over temperature threshold limit value (T0) (393), when the temperature is higher than the set value, an abnormal temperature alarm is generated, which is a series of processes related to the abnormal temperature alarm generating process. If it is less than the set temperature value (394), and performs a process related to the normal temperature, a series of processes associated with the normal temperature process (395).

In the present invention, in order to perform accurate temperature detection and to prevent malfunction due to noise, the present invention compares the current temperature value T1 with the set reference temperature value (over temperature threshold limit value T0) three times ( It is also possible to generate an abnormal temperature alarm (398) only when the temperature is higher than the temperature set continuously (396).

Thus, the purpose of the present invention, "an electronic electricity meter for preventing fire through the abnormal temperature detection function" was implemented.

The present invention has been shown and described with respect to specific preferred examples, but the present invention is not limited to these examples, and the technical idea of the present invention, which is claimed in the claims by a person of ordinary skill in the art. It includes all the various forms that can be implemented without departing from.

100: electronic electricity meter
10: power circuit section 11: power circuit
12: power failure compensation unit
20: power measurement unit 21: voltage signal detection unit
22: current signal detection unit 23: current A / D conversion unit
24: voltage A / D conversion unit 25: measurement unit
30: digital circuit unit 31: central processing unit (CPU)
32: LED for error measurement
33: oscillation circuit 34: non-volatile memory
35: communication circuit 36: power supply monitoring circuit
37: LCD display 38: operation switch
39: temperature detection sensor unit 40: signal input and output circuit unit
201: Terminal block of power meter 202, 203, 204: Current terminal
205: 206, 207, 208: screws for fixing wires
209, 213, 214: internal current line
210, 211: Internal terminal screw 212: Wire insertion hole

Claims (3)

A signal detector for detecting a voltage signal and a current signal in proportion to the voltage and current values from the power line;
An A / D converter converting the signal output from the signal detector into a digital value; and
A measuring unit calculating power data using the digital signal converted by the A / D converter; and
A central processing unit for processing the power data calculated by the measuring unit; and
A display unit for displaying the amount of power data calculated by the central processing unit; and
LED for error measurement using the power data calculated by the central processing unit; and
Non-volatile memory for storing the power amount data calculated by the central processing unit; And
Communication circuit for transmitting power-related data calculated in the central processing unit; And
An operation switch unit for inputting a parameter required for operation to the central processing unit; and
A temperature detection sensor unit mounted on a part of the electronic watt-hour meter that is likely to generate heat due to electric current and detecting an abnormal temperature; and
Signal input and output circuit unit for generating a warning signal output from the central processing unit using the signal detected from the temperature detection sensor,
The signal input and output circuit unit,
An operating power supply (VCC) is connected to the anode, and the cathode is connected to an input / output (I / O) terminal for an emergency-temp of the central processing unit through a current limiting resistor (R1). The input diode of the photocoupler
Electronic power meter for fire protection through temperature detection, comprising a phototransistor at the output terminal of a photocoupler connected with a surge protection element at both ends of the collector IC1_4 and the emitter IC1_3 to protect against surge inflow. . delete The method of claim 1,
The central processing unit
A temperature signal measured at the temperature detection sensor unit mounted on the terminal of the electronic watt-hour meter or an internal current line or an internal circuit board to detect abnormal temperature is input at regular intervals and the value converted by the A / D converter is converted into the current temperature value. Judge,
Compare the current temperature value (T1) with the set reference temperature (over temperature threshold limit value, T0), if the value is higher than the set temperature alarm process is performed,
If the current temperature value (T1) and the set temperature (over temperature threshold limit value, T0) is smaller than the set temperature value, the normal temperature process is performed.
In order to prevent a malfunction when the abnormal temperature generation process is performed, an abnormal temperature alarm is generated only when the current temperature value T1 and the set reference temperature value are larger than the set temperature value continuously for a predetermined number of times or more. Electronic electricity meter for fire protection through temperature detection.

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