KR20130099787A - Earth leakage breaker - Google Patents

Abstract

PURPOSE: An earth leakage breaker is provided to operate an electromagnet device in case of a short mode malfunction. CONSTITUTION: An earth leakage breaker (100) comprises a zero-phase current transformer (3), an earth detecting circuit (12), an electromagnet device (15), a contact, a rectifier circuit (5), and a power circuit (11). Three electric wires of a three-phase converter inserted into the zero-phase current transformer, and the zero-phase current transformer detects leakage current. The earth detecting circuit determines a level of a signal generated from the zero-phase current transformer. The electromagnet device reacts to the output of the earth detecting circuit, and operates an opening and closing unit. A contact is separated by the operating of the opening and closing unit. The rectifier circuit is connected to the electric wires, and converts AC power into DE power. The power circuit is connected to a DC output terminal, and supplies power to the earth detecting circuit and electromagnet device. If abnormal current flows in the rectifier circuit, the abnormal current flows in the electromagnet device.

Description

Earth leakage breaker {EARTH LEAKAGE BREAKER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage breaker that opens the main circuit when the leakage current of the main circuit reaches a predetermined value or more, and more particularly, to detecting a failure of an electronic component configured to realize the function. .

At present, almost all of the earth leakage circuit breakers in circulation carry out the level determination of the signal detected by the video current transformer in the earth leakage detection circuit built in, for example, an integrated circuit. When the leakage current exceeds a predetermined value, a method of opening a main circuit by outputting a drive signal to an electromagnet device incorporated in an earth leakage breaker is adopted. By the way, although these electrical leak detection circuits and an electromagnet apparatus require operating power, this operating power is taken from the inside of an earth leakage circuit breaker (for example, main circuit voltage AC 400V), and is made into predetermined voltage (for example, DC 12V). There are many cases that are supplied dropping.

Therefore, since the electronic component including the earth leakage detecting circuit is directly connected to the main circuit, surges or impulses superimposed on the main circuit enter the leakage circuit breaker, that is, the electronic component. It is necessary to prevent loss and damage in advance. Therefore, in general, a form having a surge absorbing element, for example, a surge absorber, is known at a connection point with a main circuit which is a source of generation of operating power of the ground fault circuit breaker. Alternatively, as disclosed in Patent Document 1, an electromagnet device is formed at the front end of the surge observer, the electromagnet device is excited by a relatively large current flowing through the surge observer, and the earth leakage breaker itself is tripped. The form to make is also known.

In this case, in the three-pole earth leakage circuit breaker (as can be seen from FIG. 2 of this patent document 1), it is common to take the outer two poles of the three poles, that is, the UW phase, and this is a three-phase earth leakage circuit breaker ( It is a connection between the RT phases, which is a constraint condition for use in electronics. By the way, not only this earth leakage circuit breaker, it has been a long time since the internationalization of distribution equipment, so-called global standardization. Specifically, an earth leakage circuit breaker conforming to IEC (International Standard Electrotechnical Commission) is required, but a conventional JIS (Japanese Industrial Standards) JIS C8371 (i.e. Japan-specific standard) is required. One of the differences from is that the ground fault function should operate normally when any one phase of the three-phase converter is lost.

For this reason, when voltage is taken from the R-T phase as described above, there is no problem in the S phase phase loss, but when the R phase or the T phase phase is lost, the current leakage function is immediately lost. Therefore, in order to prevent this loss, as disclosed in Patent Document 2, a form obtained by taking the operating power from each phase of a three-phase converter, rectifying it in a rectifying circuit, and lowering it to a predetermined voltage is known. According to this method, since any one phase is missing, operating power can be generated in the remaining two phases, so that the ground fault function continues to operate normally. Moreover, it turns out that the surge absorption element in this patent document 2 is a filter circuit, ie, a resistor and a capacitor provided before and after a rectification circuit.

[Patent Document 1] Japanese Patent Laid-Open No. 2000-222998 (Left 39th line to 8th right line of the fourth page) [Patent Document 2] Japanese Patent Laid-Open No. 2005-137095 (Page 6, Line 8 to Line 10)

In Patent Literature 1, since the electromagnet device (trip coil) is connected directly to the front end of all the electronic components including the surge observer, that is, the connection point with the main circuit, the surge observer is started. Even if a short mode failure forms an electronic component leading to a power supply short circuit, the electromagnet device operates with the current flowing through the power supply short circuit. Although the earth leakage breaker trips by this operation, it is likely that the user may not notice the failure at this point, i.e., a trip immediately after the short mode failure. For this reason, even if you try ON operation (in some cases, reset operation after reset operation) to the earth leakage breaker without noticing a fault, the user repeats the trip every time, so that the user can Deterioration of insulation and failure of the ground fault circuit breaker are identified.

The failure of the earth leakage breaker can be determined by removing the load-side wiring once and then attempting the above ON operation. However, in any case, the product (earth leakage breaker) can be ignited by means of a "trip" quickly. It is desirable to operate the burnout prevention, a so-called fail safe function. However, in order to realize this function, since the electromagnet device is formed directly under the connection point with the main circuit, the use of a power element in a component corresponding to this operation (thyristor in this patent document 1) cannot be avoided. In consideration of constructing a rectifying circuit from each phase of the three-phase converter described above within a limited substrate area, mounting (mounting) of the pole element and the power element to the substrate is avoided.

If only the point of time called "power-device-less" is grasped, the solution is suggested in Patent Literature 2 in which an electromagnet device is formed after a constant current circuit, that is, at a low voltage site, but the solution is cited. As can be seen from 3, in this case, even if a short mode failure occurs in the smoothing capacitor which covers one end of the filter circuit, the operation of the electromagnet device is not expected, and as a result, the earth leakage breaker ignites. ㆍ It may cause loss. In order to prevent this, it is also possible to insert a fuse in series with the smoothing capacitor, and blow the fuse with an inflow current caused by a short-circuit of the power supply, but the surge absorption capacity is inevitably lowered after the blown fuse. As a matter of course, in some cases, an appropriate voltage cannot be supplied to the ground fault detecting circuit, resulting in the loss of the ground fault function itself. As a result, the user continues to use the "leakage circuit breaker" as a simple "wiring circuit breaker" without knowing that the ground fault function is lost unless the ground fault test button is performed with the ground fault test button. That is, needless to say, it is difficult to say that it is preferable from the point of view of insulation degradation of the main circuit.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object thereof is to obtain an earth leakage breaker for operating the electromagnet device against a short-circuit failure of an electronic component while the electromagnet device is formed at a low voltage portion.

An earth leakage circuit breaker according to the present invention includes an image current transformer which passes through three power lines of a three-phase converter, detects a leakage current of the three-phase converter, and an earth leakage detection circuit for determining the level of the signal detected by the image current transformer. And an electromagnet device for activating the open / close mechanism part in response to the output of the ground fault detecting circuit, a converter contact opened by the operation of the open / close mechanism part, and the AC line of the power line to supply AC power. And a power supply circuit comprising a rectifier circuit for converting the circuit to a direct current output terminal of the rectifier circuit and a step-down circuit for supplying operating power to the earth leakage detection circuit and the electromagnet device. When an abnormal current flows in the rectifier circuit, An abnormal current is made to flow through the said electromagnet apparatus.

As described above, the present invention can provide an earth leakage circuit breaker having improved so-called fail-safe function while being so-called three-phase power harvesting.

1 is an internal circuit diagram of a three-pole earth leakage breaker according to Embodiment 1 of the present invention.

[Embodiment 1]

In Fig. 1, the earth leakage breaker 100 is connected to an open / close contact 2 for opening and closing an AC converter and a video current transformer 3 inserted in the AC converter 1, and detects a short circuit based on the detection signal. A tripping coil 15a energized through the switching elements 13 and 14 by the ground fault detecting circuit 12 and the output signal of the ground fault detecting circuit 12, and the tripping coil 15a. Power supply to both the electromagnet apparatus 15 having the tripping mechanism 15b which drives the opening-closing contact 2 openly, and the electric leakage detecting circuit 12 and the electromagnet apparatus 15 at the time of electrification. It has a power supply circuit 11. In addition, this feeding is performed by converting the AC voltage input from the AC converter 1 into a predetermined DC voltage.

The conversion to the predetermined DC voltage is performed as follows. That is, the earth leakage breaker 100 is connected to the AC converter 1, and is connected to the rectifier circuit 5 consisting of a full bridge diode of the next stage of the current limiting resistor 4 which limits the current, In addition, the next stage of the rectifier circuit 5 includes a field effect transistor 8a having a drain connected to the output side of the rectifier circuit 5, and a gate of the field effect transistor 8a. supplying a zener current to the zener diode 8b connected between the gate and the output side of the rectifier circuit 5 via a fuse 51 to be described later, and the zener current 8b. For this reason, the step-down circuit 8 which consists of the resistor 8c connected between the drain and the gate is connected. Then, power is supplied to the ground fault detecting circuit 12 and the electromagnet device 15 through the smoothing capacitors 7 and 10 connected to the input / output terminals of the step-down circuit 8, respectively. In addition, in parallel with the smoothing capacitors 7 and 10, the zener diodes 6 and 9 which absorb the surge current are connected.

Subsequently, the operation will be described. When an AC voltage of about AC 100 to 400 V is supplied from the AC converter 1 by the ON operation of the earth leakage breaker 100, the AC current Ia flows through the current limiting resistor 4, and the rectifier circuit 5 Is converted to DC voltage (Vb) at. Then, the current Ic flows to the zener diode 8b through the resistor 8c by the current Ib output from the rectifier circuit 5. At this time, when the voltage applied to the zener diode 8b, that is, the gate voltage of the field effect transistor 8a is Vc, the output voltage Vd of the step-down circuit 8 is' Vd = Vc-the field effect transistor 8a. Is the Zener voltage of the Zener diode 8b, and as described above, the Zener voltage of the Zener diode 8b is the Zener voltage of the Vd ≒ 8b minus the ON voltage of the field effect transistor 8a. Here, when the ON voltage is about 3V and the Zener voltage is about 24V, the output voltage Vd is about 21V.

On the other hand, if the Zener voltage of the Zener diode 9 is about 24V, the Vd is about 21V as described above. Therefore, the Zener diode 9 is not turned on because it does not exceed the Zener voltage of the Zener diode 9. And no current Id flows. As a result, a predetermined DC voltage (in this case, about 21 V) is supplied to the ground fault detecting circuit 12 and the electromagnet device 15. In the power supply state, when a short circuit occurs in the AC converter 1, as is well known, a signal is generated at the output of the video current transformer 3, and the short circuit detection circuit 12 outputs the video current transformer 3 by an output. When it is determined that the signal level has exceeded the predetermined reference value, the earth leakage trip signal is output to the switching element 13.

Then, the switching element 13 is turned on by the output thereof, and then the switching element 14 is turned on, thereby exciting the current to the tripping coil 15a through the switching element 14 from the power supply circuit 11. Flows. As a result, the tripping mechanism 15b operates to open and close the open / close contact 2 to prevent an accident or fire caused by the continuous leakage current flowing. In this way, since the switching elements 13 and 14 are formed after the step-down circuit, there is no need to employ a power element in these switching elements, and they are compatible with the substrate mounting of the rectifier circuit 5 made of the full diode bridge described above. Therefore, the mounting scale can be restrained as much as possible.

Here, the point of this application lies in the difference of what is called a return route to the output part side of the rectifier circuit 5 of the electric current which flows through the switching elements 13 and 14. That is, for the electronic component after the zener diode 6, for example, while the resistance value reaches the output side of the rectifier circuit 5 through the fuse 51 of about several tens of ohms, only the switching element 14 The rectifier circuit of the switching element 14 and the emitter side of the switching element 13 do not pass through the fuse 51 by the diode 52 having the cathode connected to the collector side, but through the tripping coil 15a. The output side of (5) has been reached. In other words, it is a circuit feature of the present application that the fuse 51 is not included in the current path of the tripping coil 15a, that is, the current path of the excitation current.

This feature achieves the effects mentioned below. That is, when the short circuit failure of the electronic components (for example, the zener diodes 6 and 9 and the smoothing capacitors 7 and 10) may cause fire or loss of the ground fault circuit breaker 100, If the current is such a degree as to cause such a phenomenon, the fuse 51 easily reaches the blown-off point. Then, when the voltages of both ends of the diode 52 are represented by V1 and V2, V1> V2, and this current flows through the tripping coil 15a through the diode 52. Needless to say, since this current is sufficient to operate the tripping mechanism 15b, the current flows through the electronic component causing the short mode failure by opening and closing the contact 2 as in the case of the above-described short circuit. Since the abnormal current can be interrupted, it is possible to prevent ignition and loss of the earth leakage breaker.

First of all, as mentioned in the section "Problems to Be Solved by the Invention" at this point, it is not known whether the ground fault trip is caused by a short mode failure, but the power supply circuit in which the user is ON operation, that is, a short circuit state When 11 is connected to the alternating current converter 1 again, this abnormal current also flows through the tripping coil 15a, and the earth leakage trip is repeated. By this repetition, the user can also suspect the abnormality of the ground fault circuit breaker 100, and can start from the ON operation after removing the wiring on the load side once and recognize the abnormality. In this case, it is important to prompt the user in some form to stop the use of the earth leakage breaker, which causes the short mode failure to prevent normal leakage monitoring.

Since this stoppage is realized only by the addition of a fuse and a diode, the fail-safe function can be further improved, even if the board is mounted with components necessary for continuing the operation in the phase of the three-phase converter. Thus, it is possible to provide the user with an earth leakage breaker that is convenient and reliable in use.

1: AC converter 2: switching contact
3: video current transformer 4: current limiting resistor
5: rectifier circuit 6: zener diode
7: smoothing capacitor 8: step-down circuit
9: zener diode 10: smoothing capacitor
11: power supply circuit 12: earth leakage detection circuit
13:14 switching element 15electromagnet apparatus
15a: tripping coil 15b: tripping mechanism
51: fuse 52: diode
100: earth leakage breaker

Claims (3)

A video current transformer which passes through three power lines of a three-phase converter, detects a leakage current of the three-phase converter, a ground fault detection circuit for performing a level determination of a signal detected by the video current transformer;
An electromagnet apparatus for operating the switching mechanism in response to the output of the ground fault detecting circuit;
A converter contact opened by the operation of the opening and closing mechanism,
A power supply circuit comprising a rectifying circuit connected to the power line for converting AC power of the power line into direct current power, and a step-down circuit connected to a DC output terminal of the rectifying circuit for supplying operating power to the ground fault detection circuit and an electromagnet device; In one earth leakage breaker,
And an abnormal current flows through the electromagnet device when an abnormal current flows in the rectifier circuit. The method according to claim 1,
A reaction circuit of said electromagnet device is made by a switching element, and this switching element is formed in the next stage of the said power supply circuit. The method according to claim 2,
And a fuse blown out by the abnormal current, and after the fuse blows off, the abnormal current flows the electromagnet device through a diode.

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