TWI612548B - Leakage circuit breaker - Google Patents

Abstract

An object of the present invention is to obtain an earth leakage circuit breaker capable of preventing a failure of a built-in power supply circuit by opening the earth leakage circuit breaker even in a case where an overvoltage is continuously applied to an AC line such as a withstand voltage test. The leakage circuit breaker of the present invention includes: a rectifier circuit that converts an AC voltage supplied from the AC line 1 into a DC voltage; a second constant voltage circuit 53 that steps down the output voltage of the rectifier circuit; and a second Zener diode The body 54 detects an overvoltage from the output voltage of the rectifier circuit; the second resistor 55 raises the output voltage of the second constant voltage circuit 53 when the second Zener diode 54 detects an overvoltage; 3 Zener diode 56, which absorbs a surge current when the output voltage of the second constant voltage circuit 53 reaches the first predetermined value; and overvoltage detection circuit 9, which detects that the output voltage of the second constant voltage circuit 53 reaches The trip device is driven at a predetermined value.

Description

Leakage circuit breakers

The present invention relates to an earth-leakage circuit breaker that disconnects a power-supply circuit when the leakage current of the power-supply circuit reaches a predetermined value or more, and specifically relates to an operating power source of the earth-leakage circuit breaker.

Regarding the power circuit built in this type of leakage circuit breaker, it converts the AC voltage (for example, AC100V) supplied from the AC line into a DC voltage through a rectifier circuit, and then converts the rectified DC voltage through a step-down circuit A lower voltage DC voltage (for example, DC24V) is supplied as a drive power to the leakage detection circuit and the trip device.

In the power supply circuit described above, it is necessary to protect the leakage detection circuit and the trip device from being damaged by the surge voltage when an AC line is induced to generate a surge voltage due to lightning or arc ground.

As far as its protection is concerned, a power supply circuit having the following circuits is known: a voltage detection circuit that detects a surge voltage from the output voltage of a rectifier circuit; a booster circuit that detects when a surge voltage is detected by the voltage detection circuit The output voltage of the step-down circuit is boosted; and the current sink circuit is provided on the output side of the step-down circuit, and absorbs a surge current when the output voltage of the step-down circuit reaches a predetermined value (see, for example, the following). Patent Literature 1).

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2009-95125

In the power supply circuit of the leakage circuit breaker of the conventional technology, when the surge voltage is induced inductively, the output voltage of the step-down circuit is boosted by the step-up circuit, and when the output voltage of the step-down circuit reaches a predetermined value, The current passes through a current absorbing circuit that absorbs a surge current, thereby clamping (clamping) a certain voltage to prevent the components constituting the leakage detection circuit from malfunctioning due to overvoltage. In general, even if the pulse width of the surge voltage is large, it is estimated to be at most several seconds. However, the energy that can be passed by the step-down circuit and the current sink circuit has its limit, so when the overvoltage is continuously applied, the limit will be exceeded and the step-down circuit and the current sink circuit will fail.

In the case where the above-mentioned overvoltage may be continuously applied, it is conceivable that in a control panel or the like equipped with an earth leakage circuit breaker, in order to confirm the phase-to-phase or AC line and ground (ear (earth)) of the AC line including the earth leakage circuit breaker. ) Is an insulation state and a withstand voltage test is performed (for example, 2000V, 1 minute).

Generally, for products such as earth leakage circuit breakers that have electronic circuits connected to the power supply circuit, phase-to-phase withstand voltage tests are prohibited, and only withstand voltage tests between AC lines and ground are performed. Therefore, no overvoltage is applied between the phases. However, when a load circuit is connected to the earth leakage circuit breaker as shown in Figure 7, it will be connected to the ground via components such as surge absorption capacitors and Noise filter, etc.) and the capacitance of the wire to ground instead of intentionally continuously applying an overvoltage to the phases, as a result, the power circuit of the leakage circuit breaker may be caused to fail.

The present invention has been developed by the inventors in order to solve the above-mentioned problems, and an object thereof is to obtain an earth leakage breaker having a protective function against the application of a continuous overvoltage.

The leakage circuit breaker of the present invention is provided with: an opening and closing contact, which is used to open and close a power supply circuit; a leakage current detector, which detects a leakage current of the power supply circuit; and a leakage detection circuit, which is connected to the leakage current detector and is based on the leakage current detector. The leakage signal is detected by the detection signal; the trip device is driven by the leakage detection circuit to open and close the contact; and the power supply circuit is composed of the following components: a step-down circuit that reduces the power supplied to the self-powered circuit. Electric power pressed into a constant voltage; a voltage detection circuit that detects an overvoltage from a power supply circuit; and a booster circuit that boosts the output voltage of the buck circuit when the voltage detection circuit detects an overvoltage; the leakage circuit breaker It further includes: a current sink circuit that is provided on the output side of the power circuit and absorbs a surge current when the output voltage of the power circuit reaches a first predetermined value; and an overvoltage detection circuit that is provided on the output side of the power circuit, and When the output voltage of the power circuit exceeds a second predetermined value, the trip device is driven, the second predetermined value is higher than the rated voltage of the power circuit but higher than the first predetermined value low.

The present invention uses an over-voltage detection circuit that detects a continuous over-voltage to trip open and close contacts, so it can prevent continuous over-current. The application of pressure caused the leakage circuit breaker to malfunction.

1‧‧‧ AC line

2‧‧‧ open and close contacts

3‧‧‧ zero phase current converter

4‧‧‧ Trip device

4a‧‧‧trip coil

4b‧‧‧jump mechanism

5‧‧‧ Power Circuit

6‧‧‧ Leakage Detection Circuit

6a‧‧‧Filter

6b‧‧‧Potential determiner

6c‧‧‧Signal width discriminator

6d‧‧‧Counter

6e‧‧‧Timer

6f‧‧‧Trigger Circuit

7‧‧‧The first constant voltage circuit

8‧‧‧ Switching means

9‧‧‧ overvoltage detection circuit

9a‧‧‧ 4th Zener Diode

9b‧‧‧Integrating circuit

9b1, 9b3, 10c‧‧‧ resistors

9b2‧‧‧Capacitor

9c‧‧‧Comparison circuit

10‧‧‧ Leakage test circuit

10a‧‧‧Test switch

10b‧‧‧test current generating circuit

10d‧‧‧Transistor

11‧‧‧DC line

21‧‧‧test winding

31‧‧‧ Flux brake sensor

31a‧‧‧Core

31b‧‧‧coil

31c‧‧‧Drive circuit

31d‧‧‧detection circuit

51‧‧‧ current limiting resistor

52‧‧‧Rectifier circuit

53‧‧‧The second constant voltage circuit

53a‧‧‧Field Effect Transistor (FET)

53b‧‧‧1st Zener Diode

53c‧‧‧The first resistor

54‧‧‧ 2nd Zener Diode

55‧‧‧ 2nd resistor

56‧‧‧ 3rd Zener Diode

100 to 103‧‧‧ earth leakage circuit breakers

Ia to Id‧‧‧ current

Vb to Vd‧‧‧Voltage

Fig. 1 is a circuit diagram showing a leakage circuit breaker using a power supply circuit according to a first embodiment of the present invention.

Fig. 2 is a circuit diagram showing a detailed example of the integrating circuit shown in Fig. 1.

Fig. 3 is a circuit diagram showing a leakage circuit breaker using a power supply circuit according to a second embodiment of the present invention.

Fig. 4 is a block diagram showing a detailed example of the leakage detection circuit shown in Fig. 3.

Fig. 5 is a circuit diagram showing a DC leakage breaker using a power supply circuit according to a third embodiment of the present invention.

Fig. 6 is a circuit diagram showing a DC leakage breaker using a power supply circuit according to a fourth embodiment of the present invention.

Fig. 7 is a circuit diagram for explaining a problem of the present invention with a circuit diagram when a conventional earth leakage circuit breaker is installed on a control panel.

Embodiment 1.

FIG. 1 is a circuit diagram showing a configuration of a leakage circuit breaker using a power supply circuit according to Embodiment 1 of the present invention, and FIG. 2 is a circuit diagram showing a detailed example of an integrating circuit shown in FIG.

In the first figure, the earth leakage circuit breaker 100 has: an open / close contact 2 for opening and closing the AC line 1; and an earth leakage detection circuit 6 for connecting to the AC line The zero phase comparator 3 in line 1 is a leakage current detector, and detects the leakage based on the detection signal. The trip device 4 is provided by the output signal of the leakage detection circuit 6 through switching means 8 Potential energy trip coil 4a and trip mechanism 4b that drives open and close contact 2 to trip when potential energy is applied to the trip coil 4a; and power circuit 5, which supplies power to the leakage detection circuit 6 and the trip device 4 sides.

The power supply circuit 5 converts an AC voltage input from the AC line 1 into a predetermined DC voltage to supply an exciting current to the trip coil 4a, and the first constant voltage circuit 7 converts the current to a predetermined lower voltage than the output voltage of the power circuit 5. The voltage is supplied to the leakage detection circuit 6.

Hereinafter, details of the power supply circuit 5 will be described.

A rectifier circuit 52 which is a rectifier circuit 52 constituted by a full diode bridge is connected to a rear stage of the current limit circuit which is a current limiting resistor 51 which is connected to the AC line 1 and which limits the current. The output side of the rectifier circuit 52 is connected to a step-down circuit, which is a second constant-voltage circuit 53 that steps down the output voltage. The second constant-voltage circuit 53 is composed of a field effect transistor (field effect transistor). transistor (hereinafter referred to as FET) 53a, whose drain is connected to the positive side of the output of the rectifier circuit 52; the first Zener diode 53b, which is connected to the gate of the FET 53a ) And the negative output side of the rectifier circuit 52; and the first resistor 53c (resistance value of several hundreds kΩ to several MΩ) is connected to the FET 53a that supplies a Zener current to the first Zener diode 53b Between the drain and gate.

The second resistor 53c of the second constant voltage circuit 53 is connected in parallel with a second Zener diode 54 (Zener voltage> rectifier circuit 52). Output voltage), that is, a voltage detection circuit, through which the second Zener diode 54 detects a surge voltage from the output voltage of the rectifier circuit 52. Between the gate of the FET 53a and the output negative side of the rectifier circuit 52, a second resistor 55 (resistance value of about several tens to hundreds of ohms) connected in series with the first Zener diode 53b is connected. In other words, when the surge voltage is detected by the second Zener diode 54, the output voltage of the second constant voltage circuit 53 is increased by the second resistor 55. A third Zener diode 56 is connected between the source of the FET 53a and the output negative side of the rectifier circuit 52, that is, a current sink circuit. When the output voltage of the second constant voltage circuit 53 reaches the third terminal, When the Zener voltage of the nano-diode 56 is the first predetermined value, the third Zener diode 56 absorbs a surge current.

In addition, an output terminal of the power supply circuit 5 is provided with an overvoltage detection circuit 9 that is connected in parallel with the third Zener diode 56 and drives the trip device 4 when an overvoltage is continuously input from the AC line 1 for a predetermined time.

The overvoltage detection circuit 9 is composed of the following elements: the fourth Zener diode 9a (for example, the Zener voltage is about 23V), and its cathode is connected to the cathode of the third Zener diode 56. 2 The constant voltage circuit 53 is turned on when the output voltage exceeds a second predetermined value; the integrating circuit 9b is connected to the anode of the fourth Zener diode 9a and the third Zener diode at its input. 56 anode; the comparison circuit 9c detects that the output of the integrating circuit 9b exceeds a predetermined value, that is, the time when the output voltage of the power circuit 5 reaches the second predetermined voltage and the time when the output voltage of the power circuit 5 reaches the second predetermined voltage exceeds the predetermined time ( For example, 20 msec), and the switching means 8 is driven.

As shown in Figure 2, the integrating circuit 9b consists of the following components Composition: Resistor 9b1 (resistance value is about 1kΩ to 10kΩ), one end is connected to the anode of the fourth Zener diode 9a; capacitor 9b2 (capacitance is 0.1μF to several μF), one end is connected to the resistor The other end of the resistor 9b1 is connected to the anode of the third Zener diode 56; and the resistor 9b3 (resistance value is about 1kΩ to 10kΩ) is connected in parallel with the capacitor 9b2, and both ends are connected to the comparison Circuit 9c. Here, the resistor 9b3 is used to discharge the charge of the power supply container 9b2 when the capacitor 9b2 is turned off.

In addition, a trip device 4 and a first constant voltage circuit 7 are also connected to the output end of the power circuit 5.

In addition, although the first Zener diode 53b is provided on the gate side of the FET 53a and the second resistor 55 is provided on the output negative side of the rectifier circuit 52, the second resistor 55 may be provided on the FET 53a. On the gate side, the first Zener diode 53 b is provided on the output negative side of the rectifier circuit 52.

Next, the operation will be described.

In the normal state, when an AC voltage ranging from AC100V to AC400V is supplied from the AC line 1, the AC current Ia flows through the current limiting resistor 51, and is converted into a DC voltage Vb by the rectifier circuit 52. With the current Ib output from the rectifier circuit 52, the current Ic flows through the first zener diode 53b and the second resistor 55 via the first resistor 53c. On the other hand, since the Zener voltage of the second Zener diode 54 is higher than the output voltage Vb of the rectifier circuit 52, the second Zener diode 54 does not conduct, and the current does not pass through the second Zener diode. 54 flows through the first Zener diode 53b and the second resistor 55.

At this time, the second resistor 55 has a resistance value of several tens of ohms to several hundreds of ohms relative to the first resistor 53c having a resistance value of several hundreds kΩ to several MΩ. Therefore, the current Ic flowing through the second resistor 55 depends on the first resistor 53c, and becomes a minute current of, for example, several tens μA to several hundreds μA. Therefore, the voltage drop across the second resistor 55 can be basically ignored. Therefore, if the voltage applied to the second resistor 55 and the first Zener diode 53b (the gate voltage of the FET 53a) is Vc, then Vc ≒ (the Zener voltage of the first Zener diode 53b) .

In addition, the output voltage Vd of the second constant voltage circuit 53 becomes Vd = Vc- (on-voltage of the FET 53a), and as mentioned above, Vc ≒ (the Zener voltage of the first Zener diode 53b), so Vd ≒ (Zener voltage of the first Zener diode 53b)-(on-voltage of the FET 53a), which is the rated voltage of the power supply circuit 5.

Here, if the on-voltage of the FET 53a is about 3V and the Zener voltage of the first Zener diode 53b is about 24V, the output voltage Vd of the second constant voltage circuit 53 is Vd ≒ 24V-3V = 21V degree.

In addition, if the Zener voltage of the third Zener diode 56 is set to approximately 24V, the voltage Vd applied to the third Zener diode 56 is approximately 21V and does not exceed the Zener voltage of the third Zener diode 56. Nano voltage. Therefore, the third Zener diode 56 is not turned on, and no current Id flows.

In addition, if the second predetermined value of the Zener voltage of the fourth Zener diode 9a is about 23V, the voltage Vd applied to the fourth Zener diode 9a is about 21V, so the fourth Zener diode 9a The pole body 9a is also turned off.

As a result, the output terminal of the power supply circuit 5 supplies a voltage of approximately 21 VDC to the trip coil 4 a and the first constant voltage circuit 7. The first constant voltage circuit 7 reduces the output voltage of the power supply circuit 5 and supplies a predetermined voltage. (For example, DC5V) to the leakage detection circuit 6.

In the above-mentioned power supply state, when a leakage occurs on the AC line 1, a signal is generated from the output of the zero-comparator 3, and the leakage detection circuit 6 determines that the output signal level of the zero-comparator 3 exceeds a predetermined level. Based on the reference value, a leakage trip signal is output to the switching means 8. The switching means 8 is turned on by this output, and an exciting current flows from the power supply circuit 5 to the trip coil 4a through the switching means 8, and the tripping mechanism 4b is operated to disconnect the opening and closing contact 2.

In addition, the "first predetermined value" described in the scope of patent application refers to the Zener voltage of the third Zener diode 56 described above; similarly, the "second predetermined value" described in the scope of patent application refers to Zener voltage of the aforementioned fourth Zener diode 9a.

Next, a case where the AC voltage on the AC line has a transient surge voltage superimposed will be described.

When a surge voltage of several kV is superimposed on the AC voltage, the applied voltage applied to the series circuit of the second Zener diode 54 and the first Zener diode 53b exceeds the second Zener diode 54 and the first Zener diode 54b. Since the total Zener voltage value of the Zener diode 53b, the second Zener diode 54 is also turned on.

At this time, the current Ic flowing through the second resistor 55 is increased to tens of mA from tens of μA to hundreds of μA at normal times, a voltage drop occurs in the second resistor 55, and the second resistor 55 and The voltage Vc of the first Zener diode 53b increases. For example, if the resistance value of the second resistor 55 is about 100 Ω and the current Ic is about 40 mA, the voltage drop across the second resistor 55 becomes about 4V, and the second resistor 55 and the first Zener 2 are applied. The voltage Vc of the polar body 53b becomes approximately Vc = 24V + 4V = 28V. The output voltage Vd of the second constant-voltage circuit 53 should rise to 25V based on the normal rated voltage of 21V plus the voltage drop across the second resistor 55, that is, about 4V. However, since the Zener voltage of the third Zener diode 56 (about 24V) is exceeded, the third Zener diode 56 is turned on, and the output voltage Vd of the second constant voltage circuit 53 is suppressed to the third Zener. Zener voltage (about 24V) of the nano-diode 56.

In addition, at this time, the Zener voltage 23V of the fourth Zener diode 9a is exceeded, and because the resistor 9b1 is connected in series, the resistor 9b1 shares the voltage and limits the current, so the voltage system of the power supply circuit 5 is maintained at Zener voltage (24V) of the third Zener diode 56. As a result, the fourth Zener diode 9a remains on, and the capacitor 9b2 is started to be charged by the resistor 9b1 in the integrating circuit 9b. However, in the case of a transient surge voltage, the time during which the surge voltage is superimposed on the AC voltage in the AC line 1 is very short (for example, about 1 msec to 2 msec). Therefore, the voltage of the capacitor 9b2 does not rise sufficiently high, that is, because the time when the output voltage of the power supply circuit 5 exceeds the second predetermined voltage is shorter than the predetermined time, the output of the comparison circuit 9c is not turned on, and the earth leakage circuit breaker 100 does not perform an open operation.

As described above, the earth leakage circuit breaker 100 does not perform a disconnection operation, but the output voltage of the power supply circuit 5 is suppressed to the Zener voltage of the third Zener diode 56, thereby protecting the earth leakage detection circuit 6 and the trip device 4 from being damaged. Destruction of surge voltage.

Next, a case where a continuous overvoltage is superimposed on an AC line will be described.

When an overvoltage of several kV is continuously applied to AC line 1, The applied voltage of the series circuit of the 2 zener diode 54 and the first zener diode 53b exceeds the total zener voltage value of the second zener diode 54 and the first zener diode 53b. 2 The Zener diode 54 is also turned on.

At this time, the current Ic flowing through the second resistor 55 is increased to tens of mA from tens of μA to hundreds of μA at normal times, a voltage drop occurs in the second resistor 55, and the second resistor 55 and The voltage Vc of the first Zener diode 53b increases. For example, if the resistance value of the second resistor 55 is approximately 100 Ω and the current Ic is approximately 40 mA, the voltage drop across the second resistor 55 becomes approximately 4 V, and the second resistor 55 and the first Zener 2 are applied. The voltage Vc of the polar body 53b becomes approximately Vc = 24V + 4V = 28V. The output voltage Vd of the second constant-voltage circuit 53 should rise to approximately 25V when the rated voltage of the normal voltage is approximately 21V and the voltage drop of the second resistor 55 is approximately 4V. However, since the Zener voltage (about 24V) of the third Zener diode 56 is exceeded, the third Zener diode 56 is turned on, and the output voltage Vd of the second constant voltage circuit 53 is suppressed to the third Zener. Zener voltage (about 24V) of the nano-diode 56.

At this time, since the zener voltage 23V of the fourth zener diode 9a is exceeded, the fourth zener diode 9a is also turned on, and the capacitor 9b2 is started to be charged by the resistor 9b1 in the integrating circuit 9b. In the case of a continuous overvoltage, the voltage of the capacitor 9b2 rises sufficiently high, the time when the output voltage of the power supply circuit 5 exceeds the second predetermined value exceeds the predetermined time, and the output of the comparison circuit 9c is turned on and output to the switching means 8. . By the output of the comparison circuit 9c, the switching means 8 is also turned on, and the exciting current flows from the power supply circuit 5 to the trip coil 4a through the switching means 8, and the trip mechanism 4b operates, thereby, Opening and closing contact 2 is disconnected. When the open / close contact 2 is disconnected, the power supply to the power supply circuit 5 is stopped.

According to this embodiment, the power supply circuit 5, the third Zener diode 56, and the overvoltage detection circuit 9 are provided. Among them, the power supply circuit 5 is composed of the following components: a second constant voltage circuit 53 that reduces the power supplied from the AC line 1 to a constant voltage; a second Zener diode 54 that is connected from the rectifier circuit 52 The output voltage detects an overvoltage; and the second resistor 55 boosts the output voltage of the second constant voltage circuit 53 when the second Zener diode 54 detects an overvoltage. In addition, the third Zener diode 56 is provided on the output side of the power supply circuit 5 and absorbs a surge current when the output voltage of the power supply circuit 5 reaches a first predetermined value. In addition, the overvoltage detection circuit 9 is provided on the output side of the power supply circuit 5. When the output voltage of the power supply circuit 5 exceeds a second predetermined value higher than the rated voltage of the power circuit 5 but lower than the first predetermined value, the trip device is driven. 4. Therefore, even in a case where an overvoltage is continuously applied to the AC line 1 such as a withstand voltage test, the earth leakage breaker 100 can be protected from failure by breaking the earth leakage breaker 100.

In addition, the overvoltage detection circuit 9 includes an integration circuit 9b, and drives the trip device when the output voltage of the power supply circuit 5 reaches a second predetermined value higher than the rated voltage of the power circuit 5 but lower than the first predetermined value for a predetermined time. 4. Therefore, it will not operate due to overvoltage caused by transient surge voltage, and can prevent accidental trip.

In addition, since the general leakage detection IC (Integrated Circuit) used in the leakage detection circuit 6 has a built-in comparison circuit 9c, the overvoltage detection circuit 9 can use a fourth Zener diode 9a. And an integrating circuit 9b composed of resistors 9b1, 9b3, and a capacitor 9b2. Therefore, it is possible to protect the earth leakage circuit breaker 100 from failure due to a continuous overvoltage applied to the AC line 1 by a withstand voltage test or the like at a low cost.

In addition, the output voltage of the power supply circuit 5 rises when an overvoltage is applied. Therefore, the overvoltage detection circuit 9 can be provided on the output side of the power supply circuit 5, that is, the low-voltage side. Device miniaturization.

Embodiment 2.

Fig. 3 is a circuit diagram showing the configuration of a leakage circuit breaker using a power supply circuit according to Embodiment 2 of the present invention, and Fig. 4 is a block diagram showing a detailed example of the leakage detection circuit shown in Fig. 3.

The earth leakage circuit breaker 101 of this embodiment is provided with an earth leakage test circuit 10 including an overvoltage detection circuit in place of the overvoltage detection circuit 9 of the first embodiment, and achieves various effects similar to those of the first embodiment.

In Figure 3, the leakage test circuit 10 of the earth leakage circuit breaker 101 is composed of the following elements: a fourth Zener diode 9a whose cathode is connected to the cathode of the third Zener diode 56; a test switch 10a, One end is connected to the output of the first constant voltage circuit 7 and the other end is connected to the anode of the fourth Zener diode 9a; the test current generating circuit 10b is connected to the anode of the fourth Zener diode 9a and its input The other end of the test switch 10a; the resistor 10c, one end of which is connected to the cathode of the fourth Zener diode 9a; and the transistor 10d, whose base is connected to the output of the test current generating circuit 10b, the collector (collector) is connected to the other end of the resistor 10c.

In addition, the transistor 10d which is the output of the leakage test circuit 10 The emitter is connected to one end of the test winding 21, and the other end of the test winding 21 is connected to the output negative side of the rectifier circuit 52 after passing through the zero-phase current transformer 3.

The leakage test circuit 10 and the test winding 21 constitute a normal leakage test function for checking that the leakage circuit breaker is in a normal state.

The leakage detection circuit 6 will be described in detail with reference to FIG. 4. In FIG. 4, the leakage detection circuit 6 is composed of the following components: a filter 6 a connected to the zero-phase current transformer 3, and the output signal from the zero-phase current transformer 3 will be lower than the power of the AC line 1 Harmonic components with high frequencies are removed; the potential determiner 6b receives the input signal of the filter 6a and determines the output potential of the output signal of the filter 6a; the signal width determiner 6c determines the output of the potential determiner 6b The time width of the signal; the counter 6d, which counts the output signal of the signal width discriminator 6c, outputs a pulse signal a predetermined number of times; the timer 6e, which accepts the final output signal of the signal width discriminator 6c. The counter 6d is reset after a certain time; and the trigger circuit 6f receives the pulse wave signal of the counter 6d to drive the switching element 8.

The other configurations and operations are the same as those of the first embodiment, and therefore descriptions thereof are omitted.

The operation will be described next.

When the test switch 10a is turned on for a normal leakage test operation, the power is supplied from the first constant voltage circuit 7 to the test current generating circuit 10b, and the transistor 10d is switched to switch the test current, that is, the leakage The analog current flows through the test winding 21 through the resistor 10c. When tested The test current flows through the test winding 21, and a signal is generated from the output of the current transformer 3 at zero, and when it is judged by the leakage detection circuit 6 as a leakage, it is output to the switching means 8. The switching means 8 is turned on by this output, and an exciting current flows from the power supply circuit 5 to the trip coil 4a through the switching means 8, and the trip mechanism 4b is operated, whereby the opening and closing contact 2 is disconnected and the leakage circuit breaker 101 is opened.

A case where the AC voltage on the AC line has an instantaneous surge voltage will be described.

When a surge voltage of several kV is superimposed on the AC voltage, the applied voltage applied to the series circuit of the second Zener diode 54 and the first Zener diode 53b exceeds the second Zener diode 54 and the first Zener diode 54b. Since the total Zener voltage value of the Zener diode 53b, the second Zener diode 54 is also turned on.

At this time, the current Ic flowing through the second resistor 55 is increased to tens of mA from tens of μA to hundreds of μA at normal times, a voltage drop occurs in the second resistor 55, and the second resistor 55 and The voltage Vc of the first Zener diode 53b increases. For example, if the resistance value of the second resistor 55 is approximately 100 Ω and the current Ic is approximately 40 mA, the voltage drop across the second resistor 55 becomes approximately 4 V, and the second resistor 55 and the first Zener 2 are applied. The voltage Vc of the polar body 53b becomes approximately Vc = 24V + 4V = 28V. The output voltage Vd of the second constant-voltage circuit 53 should rise to 25V based on the normal rated voltage of 21V plus the voltage drop across the second resistor 55, that is, about 4V. However, since the Zener voltage (about 24V) of the third Zener diode 56 is exceeded, the third Zener diode 56 is turned on, and the output voltage Vd of the second constant voltage circuit 53 is suppressed to the third Zener. Zener voltage (about 24V) of the nano-diode 56.

In addition, at this time, because the Zener voltage 23V of the fourth Zener diode 9a is exceeded, the fourth Zener diode 9a is turned on, the test current generating circuit 10b receives power supply, and the transistor 10d switches to switch. Therefore, a test current flows through the test winding 21. When the test current flows through the test winding 21, a signal is generated from the output of the zero-comparator 3, as shown in FIG. 4. The leakage signal from the zero-comparator 3 is after the high-frequency component is removed by the filter 6a. The input to the potential determiner 6b determines the potential. If the leakage signal is equal to or greater than a predetermined potential, the time width of the signal is then determined by the signal width discriminator 6c. If the time width of the leakage signal is also greater than the judgment value, the counter 6d is used to count the situation where the leakage signal is repeated at a commercial frequency during the period until the timer 6e resets the counter 6d.

However, in the case of a surge voltage, the time during which the surge voltage is superimposed on the AC voltage in the AC line is very short (for example, about 1 msec to 2 msec). Therefore, even if the leakage signal caused by the surge voltage is input to the signal width discriminator 6c, it will not be output from the signal width discriminator 6c due to insufficient signal width, or even if it is output from the signal width discriminator 6c, the counter 6d will not It will continue counting without outputting the pulse wave from the counter 6d. That is, since the time when the output voltage of the power supply circuit 5 exceeds the second predetermined value is shorter than the predetermined time, the output of the flip-flop circuit 6f is not turned on, and the earth leakage circuit breaker 101 does not perform an open operation.

As described above, the earth leakage circuit breaker 101 does not perform an open circuit operation, but the output voltage Vd of the second constant voltage circuit 53 is suppressed to the Zener voltage of the third Zener diode 56 to protect the earth leakage detection circuit 6 and the trip device. 4 Not damaged by surge voltage.

Next, a case where a continuous overvoltage is superimposed on the AC line 1 will be described.

When an overvoltage of several kV is continuously applied to the AC line, as in Embodiment 1, the applied voltage applied to the series circuit of the second Zener diode 54 and the first Zener diode 53b exceeds the second Zener diode. Since the total zener voltage value of the pole body 54 and the first zener diode 53b, the second zener diode 54 is also turned on.

At this time, the current Ic flowing through the second resistor 55 is increased to tens of mA from tens of μA to hundreds of μA at normal times, a voltage drop occurs in the second resistor 55, and the second resistor 55 and The voltage Vc of the first Zener diode 53b increases. For example, if the resistance value of the second resistor 55 is approximately 100 Ω and the current Ic is approximately 40 mA, the voltage drop across the second resistor 55 becomes approximately 4 V, and the second resistor 55 and the first Zener 2 are applied. The voltage Vc of the polar body 53b becomes approximately Vc = 24V + 4V = 28V. The output voltage Vd of the second constant-voltage circuit 53 should rise to 25V based on the normal rated voltage of 21V plus the voltage drop across the second resistor 55, that is, about 4V. However, since the Zener voltage (about 24V) of the third Zener diode 56 is exceeded, the third Zener diode 56 is turned on, and the output voltage Vd of the second constant voltage circuit 53 is suppressed to the third Zener. Zener voltage (about 24V) of the nano-diode 56.

In addition, because the output voltage Vd of the second constant-voltage circuit 53 exceeds the Zener voltage 23V of the fourth Zener diode 9a, the fourth Zener diode 9a is turned on, and the test current generating circuit 10b receives a power supply so that The transistor 10d switches the switch so that the test current flows through the test winding. twenty one. When the analog leakage current flows through the test winding 21, a signal is generated from the output of the zero phase current transformer 3. As shown in FIG. 4, the high frequency component is removed by the filter 6a and then input to the potential determiner 6b to determine the potential. In the case of a continuous overvoltage, since it is a predetermined potential or more, it is input to the signal width discriminator 6c. Next, the time width of the signal is determined by the signal width discriminator 6c. Since the time width of the leakage signal is also greater than the determination value, the counter 6d is used for the leakage signal in a period of approximately commercial until the timer 6e resets the counter 6d. When the frequency is repeated, it is counted, so it is judged as a leakage, and it is output to the switching means 8. The switching means 8 is turned on by this output, an exciting current flows from the power supply circuit 5 to the trip coil 4a via the switching means 8, and the trip mechanism 4b is operated, thereby opening and closing the contact 2. When the open / close contact 2 is disconnected, the power supply to the power supply circuit 5 is stopped.

As described above, when the overvoltage is continuously applied to the AC line 1, the output voltage of the power supply circuit 5 exceeds the second predetermined value, and the leakage test device 10 is driven because the time exceeding the second predetermined value exceeds the predetermined time, thereby making the The earth leakage circuit breaker 101 performs an earth leakage circuit breaker operation, thereby protecting the power circuit 5 from malfunction.

In addition, in order to prevent malfunction due to transient surges, as described above, the leakage detection circuit 6 series counts the leakage signal to be judged when it is repeated at approximately the commercial frequency. With this function, it will not be caused by transient surges. An overvoltage caused by a wave operates, and only when an overvoltage that lasts for a predetermined time or more is applied.

According to this embodiment, the power supply circuit 5, the third Zener diode 56, and the leakage test circuit 10 are provided. Among them, the power circuit 5 series It consists of the following components: a rectifier circuit 52 that converts the AC voltage supplied from the AC line 1 into a DC voltage; a second constant voltage circuit 53 that steps down the output of the rectifier circuit 52; a second Zener diode 54 An overvoltage is detected from the output voltage of the rectifier circuit 52; and a second resistor 55 boosts the output voltage of the second constant voltage circuit 53 when the second Zener diode 54 detects an overvoltage. In addition, the third Zener diode 56 is provided on the output side of the power supply circuit 5 and absorbs a surge current when the output voltage of the power supply circuit 5 reaches a first predetermined value. In addition, the leakage test circuit 10 is provided on the output side of the power supply circuit 5 and includes a tripping device for driving when the output voltage of the power supply circuit 5 reaches a second predetermined value higher than the rated voltage of the power circuit 5 but lower than the first predetermined value. 4 overvoltage detection circuit. Therefore, even in a case where an overvoltage is continuously applied to the AC line 1 such as a withstand voltage test, the earth leakage breaker 101 can be protected from failure by breaking the earth leakage breaker 101.

In addition, the leakage detection circuit 6 counts and discriminates when the leakage signal is repeated at approximately a commercial frequency. Therefore, the leakage test circuit 10 drives a trip when the output voltage of the power supply circuit 5 exceeds a second predetermined value for a predetermined time. The device 4 does not operate due to an overvoltage caused by a transient surge voltage, and can prevent an accidental disconnection.

In addition, regarding an earth leakage test circuit 10 including an overvoltage detection circuit, it is generally sufficient to add a fourth Zener diode 9a as an overvoltage detection circuit to an earth leakage test circuit having an earth leakage circuit breaker as a necessary function, and therefore it can be implemented at low cost. The earth leakage breaker 101 is protected from a failure due to a continuous overvoltage applied to the AC line 1 by a withstand voltage test or the like.

Embodiment 3.

Fig. 5 is a circuit diagram showing a configuration of a DC leakage breaker using a power supply circuit according to Embodiment 3 of the present invention.

In FIG. 5, the earth leakage breaker 102 according to the present embodiment is a person who applies the overvoltage detection circuit 9 according to Embodiment 1 to a DC earth leakage breaker. In the first embodiment, a zero phase current transformer is used as the leakage current detector, and in this embodiment, a fluxgate sensor 31 capable of detecting a DC leakage current is used as the leakage current detector. Those having the same effects as the first embodiment.

As shown in FIG. 5, the magnetic flux brake sensor 31 is provided with: a ring-shaped magnetic core (core) 31a, through which the DC line 11 is inserted; a coil (31b), which is wound around the magnetic core 31a; The circuit 31c applies a positive and negative symmetrical rectangular wave to the coil 31b so as to saturate the magnetic flux density of the coil 31b while reversing the direction; and the detection circuit 31d changes from a coil current corresponding to the coil 31b. The measured voltage detects the leakage current.

In addition, in order to prevent a failure when the positive electrode and the negative electrode are reversed, a rectifier circuit 52 provided in the first embodiment may be provided, but it is not necessary for a DC line, so it is removed and the second constant voltage circuit 53 is directly connected To the current-limiting resistor 51. Specifically, the drain of the FET 53a of the second constant voltage circuit 53 is connected to the positive side of the voltage supplied from the DC line 11, and the anode of the third Zener diode is connected to the connection point of the second resistor 55. To the negative side of the voltage supplied from the DC line 11. The operation of the power supply circuit 5 of this embodiment is the same as the operation after the DC voltage is converted by the rectifier circuit 52 in the first embodiment, and therefore description thereof is omitted.

According to this embodiment, the power supply circuit 5, the third Zener diode 56, and the overvoltage detection circuit 9 are provided. Among them, the power supply circuit 5 is composed of the following elements: a second constant voltage circuit 53 that steps down the power supplied from the DC line 11 to a constant voltage power; a second Zener diode 54 that detects the voltage from the DC line 11 The second resistor 55 boosts the output voltage of the second constant voltage circuit 53 when the second Zener diode 54 detects an overvoltage. In addition, the third Zener diode 56 is provided on the output side of the power supply circuit 5 and absorbs a surge current when the output voltage of the power supply circuit 5 reaches a first predetermined value. In addition, the overvoltage detection circuit 9 is provided on the output side of the power supply circuit 5. When the output voltage of the power supply circuit 5 exceeds a second predetermined value higher than the rated voltage of the power circuit 5 but lower than the first predetermined value, the trip device is driven. 4. Therefore, even in a case where an overvoltage is continuously applied to the DC line 11 such as a withstand voltage test, the earth leakage breaker 102 can be protected from failure by opening the earth leakage breaker 102.

Embodiment 4.

Fig. 6 is a circuit diagram showing the configuration of a DC leakage circuit breaker according to a fourth embodiment of the present invention.

In FIG. 6, the earth leakage circuit breaker 103 of the present embodiment is a case where the earth leakage circuit 10 including the overvoltage detection circuit of the embodiment 2 is applied to a DC leakage circuit breaker shown in the embodiment 3. As in the third embodiment, a magnetic flux gate sensor 31 capable of detecting a DC leakage current is used as the leakage current detector, and a leakage test circuit 10 including an overvoltage detection circuit is provided instead of the overvoltage detection circuit 9 in the third embodiment. It should be noted that various effects similar to those of the second and third embodiments are achieved.

In addition, in the present embodiment, a rectifier circuit 52 which is not provided in the third embodiment is provided in order to prevent a malfunction when the positive electrode and the negative electrode are reversed.

The magnetic flux brake sensor 31 is provided with: a ring-shaped magnetic core 31a, through which the DC line 11 is inserted; a coil 31b, which is wound around the magnetic core 31a; and a drive circuit 31c, which is based on the magnetic flux density of the coil 31b. A voltage is applied to the coil 31b with a positive-negative symmetrical rectangular wave while the reverse direction is saturated; and the detection circuit 31d detects a leakage current from a measurement voltage corresponding to a coil current flowing through the coil 31b.

The leakage test circuit 10 is composed of the following elements: the fourth Zener diode 9a, whose cathode is connected to the cathode of the third Zener diode 56, and the test switch 10a, whose one end is connected to the first constant voltage circuit 7. Output, the other end is connected to the anode of the fourth Zener diode 9a; resistor 10c, one end is connected to the cathode of the fourth Zener diode 9a; and transistor 10d, whose base is connected to the test switch 10a At the other end, the collector is connected to the other end of the resistor 10c.

In addition, the output of the leakage test circuit 10, that is, the emitter of the transistor 10d is connected to one end of the test winding 21, and the other end of the test winding 21 is connected to the magnetic core 31a of the fluxgate sensor 31 and connected to The output of the rectifier circuit 52 is negative.

The leakage test circuit 10 and the test winding 21 constitute a leakage test function required to check whether the leakage circuit breaker is in a normal state.

The other configurations and operations are the same as those of the third embodiment, and therefore descriptions thereof are omitted.

Next, the operation will be described.

In the case where the test switch 10a is turned on for a normal leakage test operation, power is supplied from the second constant voltage circuit 53 and the transistor 10d is switched, whereby the test current, that is, the leakage analog current is passed through the resistor. 10c circulates through the test winding 21. When a test current flows through the test winding 21, the output of the magnetic core 31a is judged to be a leakage by the detection circuit 31d, and then the detection circuit 31d is output to the switching means 8. The switching means 8 is turned on by this output, and the exciting current flows from the power supply circuit 5 to the trip coil 4a through the switching means 8, and the trip mechanism 4b is operated, whereby the opening and closing contact 2 is disconnected and the leakage circuit breaker 103 is opened.

Next, a case where a continuous overvoltage is superimposed on the DC line 11 will be described.

When an overvoltage of several kV is continuously applied to the DC line 11, as in Embodiment 2, the applied voltage applied to the series circuit of the second Zener diode 54 and the first Zener diode 53b exceeds the second Zener. Since the total Zener voltage value of the diode 54 and the first Zener diode 53b, the second Zener diode 54 is also turned on.

At this time, the current Ic flowing through the second resistor 55 is increased to tens of mA from tens of μA to hundreds of μA at normal times, a voltage drop occurs in the second resistor 55, and the second resistor 55 and The voltage Vc of the first Zener diode 53b increases. For example, if the resistance value of the second resistor 55 is approximately 100 Ω and the current Ic is approximately 40 mA, the voltage drop across the second resistor 55 becomes approximately 4 V, and the second resistor 55 and the first Zener 2 are applied. The voltage Vc of the polar body 53b becomes approximately Vc = 24V + 4V = 28V. The output voltage Vd of the second constant voltage circuit 53 is a rated voltage at a normal time The level of 21V, plus the voltage drop across the second resistor 55, which is about 4V, should rise to about 25V. However, since the Zener voltage (about 24V) of the third Zener diode 56 is exceeded, the third Zener diode 56 is turned on, and the output voltage Vd of the second constant voltage circuit 53 is suppressed to the third Zener. Zener voltage (about 24V) of the nano-diode 56.

In addition, since the output voltage Vd of the second constant voltage circuit 53 exceeds the Zener voltage 23V of the fourth Zener diode 9a, the fourth Zener diode 9a is turned on, and the transistor 10d is turned on, thereby simulating The leakage current flows through the test winding 21. When the simulated leakage current flows through the test winding 21, the output of the magnetic core 31a changes, and when the detection circuit 31d judges the change as leakage, it is output from the detection circuit 31d to the switching means 8. The switching means 8 is turned on by this output, an exciting current flows from the power supply circuit 5 to the trip coil 4a via the switching means 8, and the trip mechanism 4b is operated, thereby opening and closing the contact 2. When the open / close contact 2 is disconnected, the power supply to the power supply circuit 5 is stopped. In addition, the detection circuit 31d determines the leakage when the change in the output from the magnetic core 31a exceeds a predetermined time.

As described above, when the overvoltage is continuously applied for a certain period of time, the leakage test device 10 is driven, so that the leakage leakage operation is performed, and the power supply circuit 5 can be protected from failure.

According to this embodiment, the power supply circuit 5, the third Zener diode 56, and the leakage test circuit 10 are provided. Among them, the power supply circuit 5 is composed of the following elements: a second constant voltage circuit 53 that steps down the power supplied from the DC line 11 to a constant voltage power; a second Zener diode 54 that detects the voltage from the DC line 11 Overvoltage; and the second resistor 55, When the second Zener diode 54 detects an overvoltage, the output voltage of the second constant voltage circuit 53 is boosted. In addition, the third Zener diode 56 is provided on the output side of the power supply circuit 5 and absorbs a surge current when the output voltage of the power supply circuit 5 reaches a first predetermined value. In addition, the leakage test circuit 10 is provided on the output side of the power supply circuit 5 and includes a tripping device for driving when the output voltage of the power supply circuit 5 exceeds a second predetermined value higher than the rated voltage of the power circuit 5 but lower than the first predetermined value. 4 overvoltage detection circuit. Therefore, even in a case where an overvoltage is continuously applied to the DC line 11 such as a withstand voltage test, the earth leakage breaker 103 can be protected from failure by opening the earth leakage breaker 103.

1‧‧‧ AC line

2‧‧‧ open and close contacts

3‧‧‧ zero phase current converter

4‧‧‧ Trip device

4a‧‧‧trip coil

4b‧‧‧jump mechanism

5‧‧‧ Power Circuit

6‧‧‧ Leakage Detection Circuit

7‧‧‧The first constant voltage circuit

8‧‧‧ Switching means

9‧‧‧ overvoltage detection circuit

9a‧‧‧ 4th Zener Diode

9b‧‧‧Integrating circuit

9c‧‧‧Comparison circuit

51‧‧‧ current limiting resistor

52‧‧‧Rectifier circuit

53‧‧‧The second constant voltage circuit

53a‧‧‧Field Effect Transistor (FET)

53b‧‧‧1st Zener Diode

53c‧‧‧The first resistor

54‧‧‧ 2nd Zener Diode

55‧‧‧ 2nd resistor

56‧‧‧ 3rd Zener Diode

100‧‧‧ Leakage Circuit Breaker

Ia to Id‧‧‧ current

Vb to Vd‧‧‧Voltage

Claims (3)

A leakage circuit breaker is provided with: an open-close contact, which opens and closes a power supply circuit; a leakage current detector, which detects a leakage current of the foregoing power supply circuit; a leakage detection circuit, which is connected to the leakage current detector and detects the leakage current according to the foregoing The leakage signal is detected by the detection signal of the device; the trip device is driven by the leakage detection circuit to open the aforementioned opening and closing contacts; and the power supply circuit is composed of the following components: a step-down circuit that is supplied from the aforementioned power supply circuit The voltage of the power is reduced to a constant voltage; the voltage detection circuit detects an overvoltage from the power supply circuit; and the boost circuit increases the output voltage of the voltage reduction circuit when the voltage detection circuit detects the overvoltage. ; The leakage circuit breaker further includes: a current sink circuit, which is provided on the output side of the power circuit, and absorbs a surge current when the output voltage of the power circuit reaches a first predetermined value; and an overvoltage detection circuit, which is provided at An output side of the power supply circuit, and when the output voltage of the power supply circuit exceeds a second predetermined value and exceeds the second predetermined value When driving the trip device for a predetermined time, the second predetermined value higher than the rated voltage of the system power supply circuit, but lower than the first predetermined value. The leakage circuit breaker according to item 1 of the scope of patent application, wherein the overvoltage detection circuit is a driving switching element, and the switching element is connected to the trip device. The leakage circuit breaker described in item 1 of the scope of the patent application further includes a secondary winding, which is used to pass an analog leakage current through the leakage current detector, and the overvoltage detection circuit is By allowing the analog leakage current to flow through the secondary winding, the leakage detection circuit is operated to drive the trip device.