JP2003217433A - Ground fault interrupter with leakage current measuring display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground fault interrupter with a current leakage measuring display device allowing the measurement and display of a leakage current value for an electric circuit and the correction of the measurement without causing a closing contact to be switched off by the ground fault interrupter even when a current leakage exceeding a set value for the sensitivity of the ground fault interrupter is flowing in the electric circuit. <P>SOLUTION: The ground fault interrupter comprises a zero-phase current transformer 4 for detecting the current leakage in the electric circuit, a ground fault tripping device 6 having a comparison circuit 9 for comparing a voltage signal corresponding to a detection signal from the zero-phase current transformer with reference voltage and generating an output signal when the voltage signal exceeds the reference voltage and a trigger circuit 11 for opening a contact in the electric circuit in accordance with the output signal from the comparison circuit, and the current leakage measuring display device 13 for displaying the current leakage in accordance with the voltage signal. The ground fault tripping device 6 is provided with a switch 20 for short-circuiting an input signal or the output signal from the comparison circuit 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage breaker with a leakage current measuring and displaying device, which is provided with a device for measuring and displaying an electric leakage current in an electric circuit.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing the structure of a conventional earth leakage breaker with a leakage current measuring and displaying device. In this figure, 1 is an earth leakage breaker with a leakage current measuring and displaying device, 2 is a conducting main conductor which is an electric path for energizing a load, 3 is a conducting main conductor 2
Is a switching contact for turning on / off the current of 4 and 4 is a zero-phase current transformer for detecting a leakage current flowing in the current-carrying main conductor 2, and 5 is a voltage detected by the zero-phase current transformer 4. A leakage current detecting resistor 6 for converting into a signal is a leakage trip device, which is constituted by each device described below. That is, 7 is a filter circuit for extracting only a necessary frequency component from the leakage current signal detected by the leakage current detecting resistor 5, and 8 is a sensitivity current of the leakage current for performing the leakage trip operation of the leakage breaker 1. It is a leakage sensitivity setting circuit and is composed of resistors R1 and R2 connected as shown in the figure. Reference numeral 9 is a comparison circuit that compares the output of the leakage sensitivity setting circuit 8 with the reference voltage from the reference voltage circuit 10 and generates an output signal when the output of the leakage sensitivity setting circuit 8 exceeds the reference voltage. Reference numeral 11 is a trigger circuit. Upon receiving the output signal from the comparison circuit 9, the electromagnetic coil 12 is energized to turn off the switching contact 3 to cut off the power supply to the load.

Reference numeral 13 is a leakage current measuring and displaying device, which is constituted by each device described below. That is, 14 is a measurement filter circuit for extracting only the frequency component to be measured from the leakage current signal detected by the leakage current detection resistor 5,
Reference numeral 15 is a leak current A / D conversion circuit for A / D converting the output of the measurement filter circuit 14 to obtain a digital output corresponding to the leak current flowing through the energized main conductor 2, and 16 is a fault current storage circuit, which is a comparison circuit. It operates by receiving the output signal from 9.
The peak hold at that time is stored and saved as the accident leakage current value. The outputs from the leakage current A / D conversion circuit 15 and the fault current storage circuit 16 are input to the display unit 18 via the display content selection means 17, and the energization measurement result is displayed here. Note that these processes are executed by a microprocessor (not shown). Reference numeral 19 is a power supply circuit for the earth leakage trip device 6 and the earth leakage current measurement display device 13.

[0004]

The conventional earth leakage breaker with the leakage current measuring and displaying device is constructed as described above, and the sensitivity current of the earth leakage trip device 6 is the resistance R1 of the earth leakage sensitivity setting circuit 8.
Since a predetermined value is set by R2 and R2, the input signal to the comparison circuit 9 must exceed the reference voltage from the reference voltage circuit 10 when a leakage current equal to or higher than the sensitivity current setting value flows into the circuit. Then, the trigger circuit 11 operates and the earth leakage trip device 6 turns off the switching contact 3. At this time, since the output signal of the comparison circuit 9 is given to the fault current storage circuit 16, the value of the fault fault current at the time of occurrence of the fault fault is stored in the fault current storage circuit 16. Therefore, when the switching contact 3 is turned on again, the fault current value can be displayed on the display unit 18.

However, for example, when trying to estimate the cause of the earth leakage breaker 1 with the leakage current measurement display operating to trip the earth leakage, for example, a motor or the like connected to the load side of the earth leakage breaker 1 with the leakage current measurement display. Even if the load condition is changed by turning off one of the multiple devices in the above, if the leakage current that exceeds the sensitivity current value of the leakage breaker with leakage current measurement display 1 still flows, disconnect the leakage. Since the device 6 turns off the switching contact 3, the leakage current in the electric path could not be measured. For this reason, the cause estimation is not sufficient because it is necessary to estimate the cause only with the fault current value stored in the fault current storage circuit 16. Even if the load condition is changed to turn off a plurality of devices such as motors for estimating the cause, if leakage current of the sensitivity current value or more flows, leakage occurs each time. There is a problem that it is necessary to turn on and off the switching contacts of the earth leakage breaker with current measurement display 1.

When the input / output characteristics of the zero-phase current transformer 4 do not have linearity, the characteristics of the zero-phase current transformer 4 are corrected within the measurable range in order to correct the characteristics. Although it is necessary to correct the leakage current measurement value, when the measurement correction of the leakage current measurement display device 13 is performed with the leakage current of the sensitivity setting value or more, as described above, the leakage breaker with leakage current measurement display 1 However, there is a problem in that the measurement correction cannot be performed in actual energization because the switching contact 3 is turned off.

The present invention has been made in order to solve the above-mentioned problems, and leaks exceeding the sensitivity set value of the earth leakage breaker to the electric circuit to which the earth leakage breaker with a leakage current measurement display is connected. Even if the current is flowing, the leak current breaker with the leak current measurement display can measure and display the leak current value of the circuit without turning off the switching contacts, and the measurement can be corrected. The purpose is to obtain an earth leakage breaker with leakage current measurement display.

[0008]

According to the present invention, there is provided an earth leakage breaker with a leakage current measurement display, a zero-phase current transformer for detecting a leakage current in an electric circuit, and a voltage signal according to a detection signal of the zero-phase current transformer. With a reference voltage, and a comparator circuit that produces an output signal when the voltage signal exceeds the reference voltage and a trigger circuit that opens the contact of the electric circuit based on the output signal of the comparator circuit. A leakage current measuring and displaying device adapted to display a leakage current based on the voltage signal, and a switch capable of short-circuiting the input signal or the output signal of the comparison circuit to the leakage trip device. It is provided.

In the earth leakage circuit breaker with the leakage current measurement display according to the present invention, the switch is a changeover switch capable of selecting whether to input the voltage signal to the comparison circuit or to short-circuit the voltage signal. Is.

In the earth leakage breaker with leakage current measurement display according to the present invention, the switch is a changeover switch capable of selecting whether the output of the comparison circuit is given to the trigger circuit or short-circuited. It is a thing.

The earth leakage circuit breaker with a leakage current measurement display according to the present invention further includes an accident current storage circuit for storing the leakage current at that time as an accident current when the output signal of the comparison circuit is generated, and the voltage signal for the leakage current. The leakage current measurement display device is provided with a second changeover switch for changing over whether to give to the changeover switch or to input to the comparison circuit,
When the fault current is equal to or more than a predetermined value, the second changeover switch is switched to the input to the comparison circuit to prevent the input signal to the comparison circuit from being short-circuited.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of the first embodiment, and FIG. 2 is a front view showing an external configuration of a leakage breaker with a leakage current measurement display. In these figures, the same or corresponding parts as in FIG. The difference from FIG. 7 is that a switch is connected to the resistor R2 of the leakage sensitivity setting circuit 8 so that the resistor R2 and the ground can be switched and connected. That is, in the figure, reference numeral 20 denotes a changeover switch provided in the resistor R2 of the leakage sensitivity setting circuit 8. When the switch is turned on, that is, when it is switched to the side b in the drawing, the input side of the comparison circuit 9 is grounded, and therefore the sensitivity setting value Even if the leakage current of 10 flows, the comparison circuit 9 of the leakage trip device 6
The input signal of does not exceed the reference voltage from the reference voltage circuit 10, and the open / close contact 3 maintains the ON state. Further, when the changeover switch 20 is changed over to the side "a" in the figure, the circuit becomes the same as that of the conventional device of FIG. The changeover switch 20 is
It is also possible to provide in the output part of the comparison circuit 9. In this case, as will be described later, the output signal of the comparison circuit 9 can be given to the fault current storage circuit 16.

Next, the operation when the change-over switch 20 is switched and used will be described. FIG. 3 is a block diagram showing a connection example in which three devices A, B, and C are connected as loads on the load side of the earth leakage breaker with the leakage current measurement display, FIG.
FIG. 4 is an explanatory diagram showing a leakage current display value when each device in FIG. 3 is turned off. In FIG. 4, I1 is equipment A, B,
I2 is a leakage current value when only device A is turned off, I3 is a leakage current value when only device B is turned off, and I4 is only device C is turned off. The leakage current value is shown. The leakage current value when only the device A or the device B is turned off exceeds the sensitivity current value, and the leakage current value when only the device C is turned off is not more than the sensitivity current value. The operation will be described on the assumption that the earth leakage trip device 6 operates now and then the earth leakage device is specified. Changeover switch 20
Is off, that is, when the contact of the changeover switch 20 is in the normal energized state in which it is connected to the side a in the figure, the device A
If only the device B or only the device B is turned off, the earth leakage trip device 6 operates and the switching contact 3 turns off. In this case, the changeover switch 20 is turned on and switched to the side b in the drawing to remove the earth leakage. Since the leakage current value flowing through each device can be grasped without operating the device 6, the leakage device can be easily specified in a short time.

Next, the case of correcting the input / output characteristics of the zero-phase current transformer 4 will be described. FIG. 5 is a diagram showing the input / output characteristics of the zero-phase current transformer 4. When the input / output characteristics of the zero-phase current transformer 4 are corrected by the leakage current measurement display device 13, the correction points 1, 2, and 3 shown in the figure are corrected with respect to the input of the zero-phase current transformer 4. The points are set, and the actual energization correction is performed at each correction point. In this case, since the sensitivity current value is exceeded at the correction point 3, the earth leakage trip device 6 operates to operate the open / close contact 3 when the changeover switch 20 is turned off, that is, when the changeover switch is connected to the side a. Turns off, but at this time, if the changeover switch 20 is turned on, that is, it is changed over to the side b and the input signal of the comparison circuit 9 is short-circuited,
Since the leakage trip device 6 does not operate and the leakage current flows through the energized main conductor 2, the zero-phase current transformer 4 can be corrected at the correction point 3.

As described above, the changeover switch 20 for disabling the earth leakage breaker 1 is provided in the earth leakage sensitivity setting circuit 8 so that the earth leakage breaker 1 is connected to the electric circuit to which the earth leakage breaker 1 with the leakage current measurement display is connected. , Even when a leakage current exceeding the sensitivity set value of the earth leakage breaker 1 flows, the earth leakage breaker with the leakage current measurement display does not operate to trip the earth leakage, and the leakage current value of the electric circuit is measured and displayed. Therefore, the measurement correction can be performed with the leakage current equal to or higher than the sensitivity setting value. Further, since the changeover switch 20 is configured to short-circuit the input signal voltage to the comparison circuit 9, it can be realized with a simple circuit configuration.

In general, in the leakage current measurement display, the leakage trip accuracy of the leakage trip device 6 of the leakage breaker 1 is plus or minus several tens of percent of the sensitivity current, whereas the leakage current measurement display device 13 is shown. Since the accuracy of detecting the leakage current is a plus or minus several percent of the current, which is one digit higher accuracy, by providing the changeover switch 20 and deactivating the earth leakage trip device 6, as described above,
This is effective because it can accurately detect the leakage current value of the leakage device.

Embodiment 2. Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows the second embodiment.
3 is a block diagram showing the configuration of FIG. In this figure,
The same or corresponding parts are designated by the same reference numerals and the description thereof will be omitted. The difference from FIG. 1 is that the leakage sensitivity setting circuit 8
Is provided with a second changeover switch 22 to be described later, and it is possible to change over whether the voltage signal from the zero-phase current transformer is given to the changeover switch 20 or the resistor R2, and the fault current is equal to or more than a predetermined value. In the case of, the second changeover switch is changed over to the resistor R2 side. That is, in FIG. 6, 21 is the leakage current A / D
A trigger circuit that detects a leakage current from the output of the conversion circuit 15 and outputs a trigger signal to switch the second changeover switch when the value of the leakage current exceeds 150% (predetermined value) of the sensitivity current, 22 Is a second changeover switch, which is connected in series with the changeover switch 20 described above and can switch whether the voltage signal from the zero-phase current transformer 4 is applied to the changeover switch 20 or the resistor R2. Is being done. In the figure, changeover switch 2
The 0 side is indicated by d and the resistor R2 side is indicated by c.

The second changeover switch 22 is c when the trigger signal is output from the trigger circuit 21 described above.
It is designed to switch to the side. As a result, when the leakage current value exceeds 150%, the changeover switch 20
2 is switched and connected to the b side, the second changeover switch 22 is switched and connected to the c side to release the state of stopping the trip by the earth leakage trip device 6 (stopping the open drive). Since the trigger circuit 21 is also adapted to input the fault current stored in the fault current storage circuit 16, even when the fault current itself becomes 150% (predetermined value) or more of the sensitivity current, the trigger circuit 21 does not operate. Output the trigger signal.

The sensitivity current setting circuit 8 in FIG.
Shows a state in which the changeover switch 20 is turned on, that is, the changeover switch 20 is changed over and connected to the side b to investigate the cause of the accident. At the time of steady energization, the changeover switch 20 is connected to the a side. In addition, the second changeover switch 22
When investigating the cause of an accident, etc., and during normal energization,
It is connected to the d side. As described above, the trigger circuit 21
When the trigger signal is given from, that is, when the leakage current or the fault current exceeds 150% (predetermined value) of the sensitivity current, the trigger signal switches from the d side to the c side.

Since the second embodiment is configured as described above, when the leakage current of a predetermined value or more flows through the energized main conductor 2, the stop of the opening drive of the leakage trip device 6 by the changeover switch 20 is released. However, the contact 3 can be turned off, which is excellent in safety. The trigger circuit 2
It is desirable to issue an alarm output when a trigger signal is output by 1.

[0021]

The earth leakage circuit breaker with the leakage current measuring display according to the present invention is a zero-phase current transformer for detecting a leakage current in an electric circuit, and a voltage signal corresponding to a detection signal of the zero-phase current transformer is used as a reference voltage. In comparison, when the voltage signal exceeds the reference voltage, a comparison circuit that produces an output signal, and a leakage trip device having a trigger circuit that opens the contact of the electric circuit based on the output signal of the comparison circuit, and With a leakage current measuring and displaying device adapted to display the leakage current based on the voltage signal, the leakage trip device is provided with a switch capable of short-circuiting the input signal or the output signal of the comparison circuit. Therefore, even if a leakage current exceeding the sensitivity set value of the leakage breaker is flowing in the circuit to which the leakage breaker with a leakage current measurement display is connected, the leakage breaker with a leakage current measurement display will leak. Without the pull-off operation, it is possible to measure and display the path of the leakage current. In addition, it is possible to perform measurement correction with a leakage current that is equal to or higher than the sensitivity setting value.

The earth leakage breaker with the leakage current measurement display according to the present invention also inputs the voltage signal to the comparison circuit or short-circuits it, or gives the output of the comparison circuit to the trigger circuit or short-circuits it. Since the changeover switch capable of selecting whether to perform is provided, it is possible to realize the stop of the earth leakage trip operation with a simple circuit.

The earth leakage circuit breaker with a leakage current measurement display according to the present invention further includes an accident current storage circuit for storing the leakage current at that time as an accident current when the output signal of the comparison circuit is generated, and the voltage signal for the leakage current. The leakage current measurement display device is provided with a second changeover switch for changing over whether to give to the changeover switch or to input to the comparison circuit,
When the fault current is equal to or higher than a predetermined value, the second changeover switch is switched to the input to the comparison circuit to prevent a short circuit of the input signal to the comparison circuit. When leakage current flows through the energized main conductor,
It is possible to cancel the stop of the earth leakage trip operation by the changeover switch, and it is possible to obtain the earth leakage breaker with the earth leakage current measurement display device which is excellent in safety.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a front view showing an external configuration of an earth leakage breaker with a leakage current measurement display device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing an example of connection on the load side according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a leakage current display value when each device of FIG. 3 is turned off.

FIG. 5 is a diagram showing input / output characteristics of a zero-phase current transformer.

FIG. 6 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional earth leakage breaker with a leakage current measurement display device.

[Explanation of symbols]

1 earth leakage circuit breaker with leakage current measurement display device, 2 current-carrying main conductor, 3 switching contacts, 4 zero-phase current transformer,
6 earth leakage trip device, 8 earth leakage sensitivity setting circuit,
9 comparison circuit, 10 reference voltage circuit, 11, 2
1 trigger circuit, 13 leakage current measurement display device,
16 accident current storage circuit, 17 display content selection means, 18 display section, 20 changeover switch, 22 second changeover switch.

Claims (4)

[Claims] 1. A zero-phase current transformer for detecting leakage current in an electric circuit,
The voltage signal corresponding to the detection signal of the zero-phase current transformer is compared with a reference voltage, and when the voltage signal exceeds the reference voltage, a comparison circuit which produces an output signal and an output signal of the comparison circuit are used. A leakage trip device having a trigger circuit for opening the contact of the electric path, and a leakage current measurement display device capable of displaying the leakage current based on the voltage signal, the leakage trip device, the An earth leakage breaker with a leakage current measuring and displaying device, characterized in that a switch capable of short-circuiting an input signal or an output signal of a comparison circuit is provided. 2. The switch is a changeover switch capable of selecting whether to input the voltage signal to the comparison circuit or to short-circuit the voltage signal.
Earth leakage breaker with leakage current measurement display device. 3. The leakage current measurement display device according to claim 1, wherein the switch is a changeover switch capable of selecting whether to apply the output of the comparison circuit to the trigger circuit or short-circuit the switch. Earth leakage circuit breaker. 4. The fault current measuring and displaying device, when an output signal of the comparator circuit is generated, stores a fault current at that time as a fault current and a fault current storage circuit, and supplies the voltage signal to the changeover switch. A second changeover switch for changing over whether to input to the comparison circuit, and when the fault current is equal to or more than a predetermined value, the second changeover switch is changed over to an input to the comparison circuit to input to the comparison circuit. The earth leakage breaker with a leakage current measuring and displaying device according to claim 2, wherein a short circuit of the input signal is prevented.