KR20050088929A - Earth leakage breaker - Google Patents

Abstract

The present invention simplifies the configuration of a test circuit in an earth leakage circuit breaker, and enables a small and accurate earth leakage test. As a means for this, a power supply circuit for supplying power to the earth leakage detection circuit in the earth leakage circuit breaker is selected from the main circuit. It consists of a DC power supply circuit which is formed from an alternating voltage of all the phases to a predetermined DC voltage, and generates a short circuit simulation signal of AC by applying a DC voltage to test winding or short circuit of a zero phase current transformer. A simulation signal generating circuit supplied as a simulated leakage current to the detection winding, and a first test switch that is turned on during the electrical leakage test and applies the output of the DC power supply circuit to the simulation signal generating circuit is provided.

Description

Earth leakage breaker {EARTH LEAKAGE BREAKER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker for detecting an electric leakage occurring in a power distribution system connected to an electric motor and other various loads, and preventing a propagation accident.

(Prior Art)

In order to perform the operation test in an earth leakage breaker correctly, the earth leakage test circuit of an earth leakage breaker is variously devised conventionally. One example thereof is shown in Patent Document 1. The structure of the earth leakage breaker shown by this patent document 1 is shown in FIG.

The earth leakage breaker 100 of FIG. 4 has a plurality of rated voltages, for example, three rated voltages of 100, 200, and 400V. The illustrated earth leakage breaker 100 has a power supply side connection terminal 3A and a load side connection terminal 3B, and a multi-pole opening and closing portion for opening and closing a load current in a multiphase main circuit connecting the connection terminals 3A and 3B ( 8) is provided. The current leakage current in the load circuit connected to the load side terminal 3B is connected to the video current transformer 5 into which the phase 2 conductor of the main circuit connecting the switching unit 8 and the load side terminal 3B is inserted. The earth leakage detection winding 51 is wound around to detect an error. (In addition, in the following description, the main circuit is denoted by reference numeral 2). The earth leakage detection circuit 6 is obtained from the output current of the earth leakage detection winding 51. It is determined whether there is a short circuit. The detection resistor R1 is connected to the input side of the ground fault detection circuit 6. The output of the ground fault detection circuit 6 is connected to the separation device 7 which consists of a series circuit of the thyristor 71 and the separation winding 72. The power supply circuit 4 supplies electric power from the main circuit 2 to the ground fault detecting circuit 6.

When a leakage current occurs in the load circuit, the output current of the leakage detection winding 51 increases, and the voltage across the resistor R1 also increases. When the ground fault detection circuit 6 detects that the voltage across the resistor R1 exceeds a predetermined value, it outputs a drive signal, turns on the thyristor 71 of the separation device 7, and does not show the opening and closing portion 8. The unloading mechanism is disconnected and the closed contact is opened to separate the load circuit from the main circuit 2.

The earth leakage breaker 100 of FIG. 4 has a test circuit 9 for performing an operation test thereof, that is, an operation test of the earth leakage detection circuit 6. The test circuit 9 closes the test circuit during the operation test to limit the test current and the test switch 91 for supplying test current from the main circuit 2 to the test winding 52 of the image current transformer 5. Two resistive resistor elements 921 to 923, and a selector switch 93 for selecting these resistive elements.

Even if the rated voltage changes from 100V to 400V, if the test current in the test circuit 9 is set to be a constant current, the short circuit test can be performed by making the detection sensitivity of the ground fault detection circuit 6 constant. Can be corrected and the reliability can be improved. For this reason, in this earth leakage circuit breaker, the rated voltages of 100 V, 200 V and 400 V so that the test current supplied to the test winding 52 is constant even if the resistance value of each of the current limiting resistor elements 921, 922 and 923 changes. It is set to a value corresponding to, so that one of the current limiting resistor elements 921 to 923 can be selected by the selection switch 93 according to the rated voltage used.

In an earth leakage circuit breaker provided with such a test circuit, even if the rated voltage used varies between 100 V and 400 V, the test circuit is selected by operating the selector switch 93 according to the rated voltage at that time to select the corresponding resistance element. Since the test current supplied to the test winding 52 of the video current transformer 5 from (9) can be made constant, a test can be performed correctly and stably.

However, in such a conventional apparatus, since it is necessary to provide the number of current limiting resistor elements and the selection switch corresponding to the kind of rated voltage used, manufacturing cost is increased by the increase of the number of components, such as the installation space of a test circuit becomes large. Raises a problem.

In particular, since a large voltage is always applied between the contacts at the time of opening the test switch, particularly at a high rated voltage, it is necessary to increase the breakdown voltage of the test switch to increase the breakdown voltage. There is a problem.

In order to solve such a problem, the earth leakage breaker shown in patent document 2 is proposed. FIG. 5 shows a configuration of an earth leakage breaker shown in Patent Document 2. As shown in FIG.

The circuit breaker 200 of FIG. 5 includes an opening and closing portion 8 inserted into the conductor 2 of the main phase of the main circuit, an image current transformer 5 into which the conductor 2 of the main phase of the main circuit is inserted, and the image current transformer 5. (C) rectifies the AC voltage between the two phases of the ground fault detection winding 51 wound around the ground, the ground fault detection circuit 6 connected to the output side of the ground fault detection winding 51, and the three-phase main circuit, A separator 7 having a power supply circuit 4 to be supplied to the ground fault detection circuit 6 and a thyristor 71 connected to an output terminal of the ground fault detection circuit 6 is provided. The thyristor 71 conducts by a drive signal indicating the ground fault detection output from the ground fault detection circuit 6. When the thyristor 71 conducts, the separating device 7 disconnects the input mechanism (not shown) of the opening / closing part 8 and opens the closed contact to cut off the main circuit 2.

The earth leakage breaker 200 also has a test circuit 90 for performing its operation test. The test circuit 90 is connected to the power supply circuit 4 via a test switch 91 and has a simulated signal generating circuit 92 for generating a simulated earth leakage signal. When the DC switch is applied from the power supply circuit 4 by turning on the test switch 91, the simulated signal generating circuit 92 generates a simulated short circuit signal of alternating current, and the ground fault detection circuit 6 simulates a short circuit. A signal can be given to test the operation of the ground fault detection.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-78187

[Patent Document 2] Japanese Patent Application Laid-Open No. 8-149687

 In the conventional earth leakage breaker of FIG. 5, the test switch 91 and the simulated signal generation circuit 92 constituting the test circuit 90 are connected to the DC power supply circuit 4 that feeds the earth leakage detection circuit 6. Therefore, it becomes a predetermined voltage irrespective of the voltage of the main circuit 2, and solves the problem in the conventional apparatus of FIG. 4 which requires the manufacturing cost of a test circuit to become high and the withstand voltage of a test switch to be made high. can do. However, in the conventional apparatus of FIG. 5, since the DC power supply circuit 4 converts the AC voltage between the two phases of the multiphase main circuit into a DC voltage, a short circuit test is performed when an imaging occurs on the AC voltage. The problem arises that it cannot be carried out.

In order to solve such a problem, the present invention is intended to provide a short circuit test even when an image is lost in one phase of the main circuit, and is provided with a test circuit that is small in size and has a small installation space. An object of the present invention is to provide an earth leakage breaker capable of testing.

(Means to solve the task)

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an open / close unit for opening and closing a multiphase main circuit, an image current transformer for detecting a current leakage current of the main circuit, and the presence or absence of a current leakage from the output current of the current detection winding of the image current transformer A short circuit detecting circuit for determining a circuit breaker, a strip gear for breaking the main circuit by tripping the open / close section by an output signal indicating a short circuit occurrence of the ground fault detecting circuit, and supplying power to the ground fault detecting circuit. An earth leakage circuit breaker provided with a power supply circuit comprising: a DC power supply circuit configured to form the power supply circuit from an AC voltage of the phase of the main circuit to a predetermined DC voltage, and an AC leakage simulation signal by applying a DC voltage. To generate a simulated leakage current to the test winding or the ground fault detection winding of the image current transformer. And, the signals generated by circuit simulation on during the short-circuit test in claim characterized in that provided for the test switch 1 connected to the output of said DC power supply circuit

Further, in the earth leakage breaker, a second test switch which is complementary to the first test switch is provided on the input side of the earth leakage detection circuit, and the sensitivity is set through the second test switch. It is good to connect the circuit.

Further, in the earth leakage breaker, the first and second test switches may be configured to be switches having the same structure and operated through a common operation bar.

EMBODIMENT OF THE INVENTION Hereinafter, an Example demonstrates this invention based on drawing.

Example 1

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

In FIG. 1, the code | symbol 1 is an earth leakage circuit breaker, Usually, all the components are accommodated in the mold case made of insulated resin, and it is formed compactly. The earth leakage breaker 1 includes a main circuit 2 for connecting the power supply side connection terminal 3A and the load side connection terminal 3B, an opening / closing part 8 for opening and closing the main circuit 2 and the main circuit 2. An electric current detecting circuit for detecting a current leakage in the video current transformer 5 that detects an electric current flowing through the main circuit and the electric current detection current of the electric current detecting winding 51 of the video current transformer 5 is determined. (6) An operating power is supplied to the disconnecting device 7 and the ground fault detecting circuit 6 that disconnect the closing mechanism by separating the input mechanism of the opening and closing portion 8 by an output signal indicating the ground fault of the ground fault detecting circuit 6. And a DC power supply circuit 4 for supplying power.

The power supply circuit 4 controls the output current of the rectifier circuit 41 and the rectifier circuit 41 for rectifying and converting the alternating voltage of the phases of the main circuit 2 of the multiphase into a direct current voltage. It consists of the constant current circuit 42 and the constant voltage diode ZD, and produces | generates the predetermined | prescribed DC voltage of about 5V which an electronic circuit requires. The power supply circuit 4 simulates a signal generating circuit 12 composed of an oscillation circuit which generates a current leakage current of a frequency alternating current, such as a commercial frequency, through a first test switch 11a which is operated on when a ground fault test is performed. ) Is connected, and the output of the simulated signal generation circuit 12 is connected to the test winding 52 provided in the video current transformer 5 to constitute the test circuit 10.

When the constant current circuit 42 and the constant voltage diode are provided in the power supply circuit 4, the short circuit detection circuit 6 and the simulated signal can be supplied with a predetermined DC voltage without using a step-down element with a large loss even when the rated voltage changes. It can supply to the generator circuit 12.

To the output of the earth leakage detection circuit 51 of the video current transformer 5, a detection resistor 53 for extracting a detection signal and a sensitivity setting unit 54 for adjusting the detection sensitivity are paralleled, and a short circuit from both ends of the detection resistor is performed. The earth leakage detection signal is input to the detection circuit 6.

When a leakage current occurs in the load circuit, the output current of the leakage detection winding 51 increases, and the voltage at both ends of the detection resistor 53 also increases. When the ground fault detection circuit 6 detects that the voltage across the resistor 53 exceeds a predetermined value, the circuit breaker 7 drives the separation device 7 to forcibly open the closed contact of the opening and closing part 8 to circulate the load circuit. Separate from the furnace (2).

A sensitivity tester 54 has a second test switch (1) which performs a complementary operation in which the test switch 11a is turned on when the test switch 11a is turned on and turned on when the test switch 11a is turned on in series with the first test switch 11a. 11b) is connected.

When the first test switch 11a of the test circuit 10 in FIG. 1 is turned on for the electrical leakage test, power is supplied from the power supply circuit 4 to the simulation signal generation circuit 12, so that this oscillates. An earth leakage simulation signal having the same frequency as the commercial frequency of alternating current is generated, and a predetermined simulated earth leakage current It flows through the test winding 52. The ground fault detection current Is corresponding to this simulated current It flows through the detection winding 51 of the video current transformer 5, and a ground fault detection voltage is generated at both ends of the detection resistor 53. The earth leakage detection circuit 6 determines that an earth leakage occurs when the earth leakage detection voltage reaches a predetermined value or more, and drives the separation device 7 to disconnect the opening and closing portion 8 to cut off the main circuit, thereby completing a series of test operations. do.

In this process, the second test switch 11b is turned off in conjunction with the on of the first test switch 11a to separate the sensitivity setter 54 from the detection winding 51. For this reason, since the setting state of the sensitivity setter is irrelevant at the time of testing, even if the rated voltage to be used changes, the predetermined resistance voltage can always be obtained from the detection resistor 53, regardless of the rated voltage to be used. The operation test of the ground fault detection circuit 6 can be performed correctly, and the reliability of a ground fault test can be improved.

As described above, in the first embodiment, the DC power supply circuit 4 converts the AC voltage of all phases of the multiphase main circuit into a DC voltage, and the simulation signal generation circuit 12 relates to the magnitude of the AC voltage of the main circuit. Since a current leakage test is performed with a predetermined current leakage simulation current to make the detection sensitivity constant, an earth leakage breaker test can be accurately performed even when an image is formed in one phase of the main circuit.

Example 2

Next, the configuration of the second embodiment of the present invention is shown in FIG.

This Example 2 shows the specific structure of the test switch 11a and 11b in Example 1. As shown in FIG.

Push-type switches of the same structure (on when pressed, and on when both sides of the circuit board 20 on which the DC power supply circuit 4 and the earth leakage detecting circuit 6 are mounted are turned on, and when the pressure is released, the switch returns to off). The two test switches 11a and 11b consisting of switches) are fixedly mounted. The crank-shaped test switch operation bar 22 is inserted into the through hole 21 provided in the circuit board 20, and supported to be pushed down by the circuit board 20 through the return spring 23. The operation button 24 which performs a press operation at the time of a test is provided on the upper press part 22a of the switch operation bar 22. As shown in FIG.

In the standby state in which the ground fault test is not performed, the operation bar 22 is pushed up by the return spring 23 as shown in Fig. 2A. For this reason, since the upper press part 22a of the operation bar 22 is separated from the test switch 11a, and the lower press part 22b will be in the state which presses the test switch 11b, the switch 11a will be The switch 11b is turned off. As a result, the sensitivity setting circuit 54 in FIG. 1 is connected to the detection winding 51 of the video current transformer 5 to cut off the power supply of the simulation signal generating circuit 12.

In the short-circuit test, by pushing the test button part 24 and pushing down the operation bar 22 as shown in FIG. 2 (b), the upper press part 22a pushes the 1st test switch 11a. It pressurizes and turns it on, and the lower pressurizing part 22b separates from the 2nd test switch 11b, and turns it off. As a result, the simulation signal circuit 12 is connected to the power supply circuit for oscillation, and a ground fault simulation signal is applied to the test winding 52 to perform a ground fault operation test.

In addition, the operation bar 22 may use not only the crank form shown in FIG. 2 but the c-shaped operation bar 22 as shown in FIG. In this case, the two test switches 11a and 11b are fixed to the same position on both front and back sides of the circuit board 20.

When the operation bars as shown in Figs. 2 and 3 are used as the mechanism for interlocking the first and second test switches, a switch having the same structure can be used for the two switches that operate complementarily. This makes the test switch compact and inexpensive.

In the present invention, since the DC power supply circuit supplied to the ground fault detection circuit and the simulated signal generation circuit is configured to convert from the AC voltage of the phase of the multi-phase main circuit to the DC voltage, the ground fault test is performed even if an image formation occurs in one phase of the main circuit. In addition, since a circuit for generating a simulated short-circuit current is driven by a DC power supply circuit, a constant test current is supplied during the test regardless of the magnitude of the rated voltage of the main circuit. For this reason, according to this invention, since a constant test current can always be supplied irrespective of the magnitude | size of rated voltage, the effect which can carry out an earth leakage test correctly and stably can be acquired. Since the voltage between the contacts at the time of opening the test switch becomes the low output voltage of the DC power supply circuit, and the contact interval can be made small, the effect of making the test switch small can also be obtained.

When the sensitivity setting circuit for setting the detection sensitivity is provided in the ground fault detection circuit, the sensitivity setting circuit is disconnected in conjunction with the first test switch to always detect the detection sensitivity of the ground fault detection circuit. Since it can be made constant, it has an effect which can perform an operation test correctly and stably.

As described above, the present invention forms a ground fault simulation signal in a simulated signal generation circuit fed by a DC power supply circuit which converts an alternating voltage of a phase of a main circuit of a polyphase main circuit into a constant voltage DC voltage. Since the ground fault test can be performed even if an phase is lost in one phase of the AC main circuit, the reliability of the ground fault test of the ground fault breaker can be improved.

1 is a block diagram showing a circuit breaker of the present invention.

2 is a longitudinal sectional view showing an example of an operation bar of a test switch used in the present invention.

3 is a longitudinal sectional view showing another example of an operation bar of a test switch used in the present invention.

Figure 4 is a block diagram showing a conventional earth leakage breaker.

Figure 5 is a block diagram showing another conventional circuit breaker.

(Explanation of symbols for the main parts of the drawing)

1: leakage circuit breaker 2: main circuit

3A: Power supply side connection terminal 3B: Load side connection terminal

4: DC power circuit 5: video current transformer

51: detection winding 52: test winding

6: ground fault detection circuit 7: strip gear

8: switch 10: test circuit

11a: first test switch 11b: second test switch

12: simulation signal generating circuit

Claims (3)

An electric leakage detecting circuit for determining whether an electric leakage has occurred from an opening / closing part for opening and closing a multiphase main circuit, a zero phase current transformer for detecting an electric current leakage current of the main circuit, and an output current of the electric current detecting winding of the image current transformer. And a strip gear for breaking the main circuit by tripping the open / close section by an output signal indicating the occurrence of a ground fault of the ground fault detection circuit, and a power supply circuit for supplying power to the ground fault detection circuit. In the circuit breaker, The power supply circuit is constituted by a DC power supply circuit which forms a predetermined DC voltage from an AC voltage of all the phases of the main circuit, and generates an AC leakage simulation signal by applying a DC voltage to the image current transformer. And a first test switch for supplying the simulated signal generating circuit to the test winding or the ground fault detecting winding as a simulated leakage current, and connecting the simulated signal generating circuit to the output of the DC power supply circuit when the ground fault test is performed. Earth leakage breaker. The method of claim 1, A second test switch is provided on an input side of the earth leakage detection circuit, which is complementary to the first test switch, and a sensitivity setting circuit is connected through the second test switch. breaker. The method of claim 2, An earth leakage circuit breaker, characterized in that the first and second test switches are switches having the same structure and are operated through a common operation bar.