JPS59194626A - Leakage breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an earth leakage breaker that detects the amount of current flowing through a welding machine and detects electric leakage.

Conventionally, as this type of earth leakage breaker, there was one shown in Figure 1.

In Figure 1, (1) is a power supply terminal, (2) is a load terminal, (3) is a switch that opens and closes electric circuit A, and (4) is an overcurrent device that detects tt overcurrent and has a timer element. (5) is a zero-phase current transformer that detects the ground fault current; (6) is an electronic control unit that is connected to the zero-phase current transformer (5) and amplifies the ground fault current; (7) is a disconnection element; This electromagnetic device has the function of operating when the amplified ground fault current exceeds a predetermined value to open and close the switch (3). (8) is a display button that is linked to the electromagnetic device (7) and indicates the occurrence of a ground fault, and (9) is an abnormal current detection circuit that is connected to the load circuit connected to the load terminal (2), such as a welding machine (Fig. When the device (not shown) is energized, the amount of energization is detected through the signal input terminal (11), and it is activated when the energization continues for a predetermined period of time. ing. At (lO), the abnormal current detection circuit (8) is activated and the relay (9a) is opened. test resistor (1) that passes the test current to the zero-phase current transformer (5) by
2) is a test button, which has a normally closed contact (12A) and a normally closed contact (12B), and when the test button (12) is pushed in, it closes and uses the voltage from the load terminal (2) as a signal source. The signal is input to the abnormal current detection circuit (8) as a signal.

Next, the operation will be explained.

The earth leakage breaker has two functions: protection against a ground fault on the load terminal (2) side and protection against abnormal energization of a load such as a welding machine.

In the former, if a ground fault occurs after the load terminal (2), an output is generated to the secondary side of the zero-phase current transformer (5), amplified by the electronic control unit (6), and the ground fault current is increased to a specified level. When a value greater than or equal to the value is reached, an opening/closing signal is sent to the electromagnetic device (7). This opens the switch (3) and the display button (
8) is displayed to indicate a ground fault.

On the other hand, in the latter case, when the load circuit (welding machine) is energized, voltage is detected from the signal input terminal (11) and a signal is sent to the abnormal current detection circuit (8). When the set value is exceeded, the relay switch (9a) is closed. As a result, a ground fault current flows through the load terminal (2), the zero-phase current transformer (5), the test resistor (10), and the relay (9a). Due to the generation of this ground fault current, it operates in the same way as the ground fault accident described above. Further, the operation by the test button (12) can also be performed in the same manner as described in "L" by applying a voltage signal to the abnormal current detection circuit (8).

A conventional earth leakage breaker is configured as described above, and has an external signal input terminal (1
1) and a signal line, and also requires a relay (9a) inside the abnormal current detection circuit (9), which makes it extremely large and difficult to integrate into a conventional earth leakage breaker. There was a drawback that the current detection circuit (9) had to be installed separately.

This invention was made to eliminate the above-mentioned conventional drawbacks, and it is possible to eliminate the need for a relay in connection with a load circuit or in an abnormal current detection circuit, and by downsizing the abnormal current detection circuit, The purpose of the present invention is to provide an earth leakage breaker that can be easily integrated with a ground fault detector.

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 2, (6) is an electronic circuit that operates upon receiving the output from the zero-phase current transformer (5) and sends a switching signal to the electromagnetic device (?) of the switch (3) connected to electric circuit A. control unit, (9)
is an abnormal current detection circuit (see Fig. 3) consisting of a detection circuit (9C) for detecting abnormal current of the transformer (13) installed in electric line A and an actuation circuit (8d), and (14) is an electronic control section. (6) and the abnormal current/detection circuit (9).

As shown in FIG. 3, the electronic control section (8) is connected to a detection circuit (6C) having an amplifier and a cyrisk (6C) that is electrically connected by the output from the detection circuit (6C) and drives the electromagnetic device (7). 15) and a capacitor (16) that absorbs the noise of the cyrisk (15). The operating circuit (9d) of the abnormal current detection circuit (8) is
18), a capacitor (18) that prevents the thyristor (18) from malfunctioning due to noise, a test resistor (lO), and the thyristor (+7a), (17b), and a connection line from the operating circuit (9d). (30a) ,'(
3ob) penetrate the zero-phase current transformer (5) in mutually opposite directions. The power supply section (14) also includes a control power transformer (14a) that lowers the voltage from high voltage to low voltage and insulates the high voltage section and the low voltage section, and a rectifier diode (14b) (14c) that converts alternating current to direct current. (14d) (14e)
and a Hirayoshi capacitor (14f) for pulse wave removal.

Next, the operation will be explained. In Figures 2 to 4, when the breaker is closed, that is, when the switch (3) is closed, the control power transformer 1 is connected to the electronic control unit (6) and the abnormal current detection circuit (9). Power is supplied through (14a). In this state, when a ground fault occurs in the load circuit connected after the load terminal (2), an output is generated on the secondary side of the zero-phase current transformer (5), and the electronic control unit (6 ), and when the ground fault current reaches a predetermined value or more -L, an output is output to the gate of the thyristor (15) and the thyristor (15) becomes conductive. As a result, the electromagnetic device (7) is energized to disengage the mechanical part (not shown) of the circuit breaker, open the switch (3), and open the electric circuit A, at the same time the display button (8) protrudes. do.

” - When a load circuit such as a welding machine is energized under normal conditions without any ground faults as described above, the abnormal current □ detection transformer (13) detects the current, which is then amplified and timed. It is sent to the abnormal current detection circuit (9) having a When the detection circuit (8C) of the abnormal current detection circuit (9) is energized for a period longer than the set time, an output is output to the thyristor (18) and the circuit becomes conductive. Due to the conduction of the thyristor (18), the current from the control power transformer (14a) is transferred to the thyristor (
17a, ) (17b), the test resistor (10), and the thyristor (18). The diode at this time (
1? The current waveforms flowing through a) and diode' (1?b) become half-wave currents as shown in FIGS. 4(A) and 4(B). Therefore, the secondary output waveform of the zero-phase current transformer (5) is also a half-wave output waveform proportional to the primary waveform, but when the connecting wires (30a) and (30b) pass through the zero-phase current transformer (5), As shown in FIG. 3, since the directions are opposite to each other, the secondary output waveform of the zero-phase current transformer (5) becomes an alternating current as shown in FIG. 4(C). Similar to a ground fault, this output is amplified by the detection circuit (6a) of the electronic control section (8) and is activated by switching the thyristor (15) and energizing the electromagnetic device (7). circuit, and at the same time the display button (8) is projected to display the abnormal current.

Therefore, according to the above configuration, by using the abnormal current detection transformer (13), there is no need to connect the signal power line from the outside, and compared to the conventional example shown in FIG. 1, the relay can also be eliminated. In addition to being able to reduce costs, the abnormal current detection circuit can be downsized, and it is easy to integrate the earth fault detector into the case of the earth leakage breaker. Further, since the test current is also taken from the low voltage side of the control power transformer (14a), the configuration of the operating circuit (8d) is also simplified. Furthermore, in the method of passing the connecting wires (3oa) (3ob) to the zero-phase current transformer (5), if the connecting wires (30a) (30b) are passed through in the same direction, the flow will be pulsating and the amplitude will be small and unstable. However, since the above-mentioned lines (30a) and (30b) are connected in opposite directions, a sine wave is formed and a stable output can be obtained.

As explained in Section 2, according to the present invention, the connection with the load circuit and the relay in the abnormal current detection circuit can be eliminated, so the abnormal current detection circuit can be miniaturized, and it can be installed inside the case of the earth leakage breaker. It is possible to provide an earth leakage breaker that can be easily integrated with a ground fault detector.

[Brief explanation of drawings]

11Δ is a circuit diagram showing a conventional earth leakage breaker, FIG. 2 is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a circuit diagram showing main parts of FIG. 2 in detail, and FIG. 4 is the same circuit diagram. It is a waveform diagram of an example. (3)...Switch, (5)...Zero phase current transformer, (6)
...Electronic control unit, (8) Society...Abnormal current detection circuit, (
9c)...detection circuit, (8d) φ/φ operation circuit, A.
...Electric circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent: Masuo Oiwa Figure 4: Mr. Commissioner of the Japan Patent Office 1, Indication of the case: Patent Application No. 58-068544 2
, Name of the invention Earth leakage breaker 3, Person making the amendment 5, "Detailed description of the invention" of the specification to be amended. 6. Correction Uchitani

Claims (1)

[Claims] (1) An electronic control unit that operates upon receiving the output from the zero-phase current transformer and sends a switching signal to the connected switch; an abnormal current detection circuit that is connected in series with the thyristor and has an operating circuit that sends an alternating current signal so as to generate a switching signal to the zero-phase current transformer by conduction of the thyristor; An earth leakage breaker characterized by comprising: