JP3189930B2 - Earth leakage breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a leakage current of a main circuit with a zero-phase current transformer, opens a contact by a trip coil, and indicates that the contact has been opened by the leakage current. The present invention relates to an earth leakage breaker provided with a display device.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory view of a tripping device for an earth leakage circuit breaker. When a leakage current of a main circuit is generated, an exciting current flows through a trip coil TC to attract a plunger 21, and the plunger 21 is removed. The tripping plate 22 is actuated by the suction, and the engaging piece 24 for opening the contact 23 and the earth leakage display button 25 for displaying the state are operated. When the contact 23 in the open state is closed again by operating the handle 26 to close the circuit, the earth leakage breaker 27 can reset the earth leakage display button 25 in conjunction with the handle 26.
In such an earth leakage circuit breaker 27, the excitation of the trip coil TC of the prior art for bringing the contact 23 into an open circuit state is generally performed by the methods shown in FIGS.

FIG. 4 shows a method of exciting a trip coil TC by a half-wave rectified current. When a leakage current is generated in a main circuit 28, the leakage current is detected by a zero-phase current transformer ZCT and the leakage current is set to a set value. Is exceeded, a signal is output from the terminal A of the IC, the thyristor SCR is turned on, and the half-wave rectified current flows from the R phase through the trip coil TC, the thyristor SCR, and the diode D in the T phase path. The coil TC is excited, and the contact 23 of the earth leakage breaker 27 is opened to cut off the main circuit 28.

FIG. 5 shows a method of exciting a trip coil TC by a full-wave rectified current. When a leakage current occurs in a main circuit 28, the leakage current is detected by a zero-phase current transformer ZCT, and the leakage current is set to a set value. Is exceeded, a signal is output from the terminal A of the IC, the thyristor SCR is turned on, and the full-wave rectified current flows from the R phase to the T phase path via the diode D1, the trip coil TC, the thyristor SCR, the diode D3, and Since the T-phase flows through the R-phase path through the diode D2, the trip coil TC, the thyristor SCR, and the diode D4, the trip coil TC is excited and the leakage breaker 2
The contact 23 of No. 7 is opened to cut off the main circuit 28.

[0005]

However, according to the above prior art, in the case of FIG. 4, the trip coil TC is turned on while the thyristor SCR is on as shown in FIG.
When a half-wave rectified current of half a cycle flows through the plunger 21, the plunger 21 shown in FIG. 3 is attracted to the trip coil TC, the tripping plate 22 pushes the engaging piece 24, the separator 29 rises, and the contact 23 is opened. At the same time, the leakage display button 25 protrudes due to the rise of the separator 29. However, as shown in FIG. 7, when the timing is poor and the time of the exciting current flowing through the trip coil TC while the thyristor SCR is in the ON state is short, FIG. The plunger 21 is sucked, the tripping plate 22 pushes the engaging piece 24, and the separator 29 rises to open the contact 23. However, the excitation time of the trip coil TC is shortened, and the plunger 21 is pulled before the separator 29 rises. Since the release plate 22 returns to the position before the suction, the main circuit 28 is cut off by the generation of the leakage current, but the connection between the leakage display button 25 and the release plate 22 is performed. The leakage display button 25 does not protrude, so that the display failure of the leakage display button 25 occurs, and it is not possible to determine that the interruption operation of the leakage breaker 27 is caused by leakage current. .

In the case of FIG. 5, while the thyristor SCR is in the ON state as shown in FIG.
Since the full-wave rectified current flows through C, the plunger 21 is completely attracted to the trip coil TC, the tripping plate 22 pushes the engaging piece 24, the separator 29 rises and the contact 23 is opened, and the separator 29 is opened. When the terminal on the power supply side and the load side of the earth leakage breaker 27 is reversely connected to the main circuit 28,
Even after the contact 23 is opened due to the generation of the leakage current, the state in which the voltage is applied to the electronic circuits between the varistors ZNR continues, so that the normal thyristor SCR is turned off at the zero cross of the current.
Is a full-wave rectified current, it is difficult to detect the zero point of the current, and the thyristor SCR may not be turned off. At that time, the thyristor SCR keeps on and the trip coil TC Since the current flows, there is a disadvantage that the trip coil TC, the thyristor SCR, and the diodes D1, D2, D3, and D4 may be burned.

Accordingly, the present invention provides a highly reliable earth leakage circuit breaker that ensures that the contacts are opened and the earth leakage display device operates when leakage current occurs, and that the electronic components do not burn out even when the connection is reversed. Is to do.

[0008]

In order to solve the above-mentioned problems, an earth leakage breaker of the present invention has two sets of rectifiers and switching elements connected in series connected in parallel to a trip coil, and a rectifier and a switching element. The connection points with the elements are respectively connected to main circuits having different polarities of the earth leakage breaker.

[0009]

[Function] When a leakage current is generated in the main circuit, it is detected by a zero-phase current transformer, and when the leakage current exceeds a set value, the thyristor is ignited, and the exciting current is reduced from the R phase to one of the switching element and the trip coil. , A T-phase path via the other switching element connected in parallel with one switching element, and T
The current flows from the phase through the R-phase path via the other switching element, the trip coil, and one rectifying element connected in parallel with the other switching element, and the excitation of the trip coil activates the contacts of the earth leakage breaker and the earth leakage display device. .

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of an earth leakage breaker according to the present invention.

FIG. 1 is an explanatory diagram of a circuit configuration of an earth leakage circuit breaker according to the present invention, wherein a diode D1 and a thyristor SCR2 and a diode D2 and a thyristor SCR are connected in series.
1 in parallel with the trip coil TC, and a connection point between the diode D1 and the thyristor SCR2 and a connection point between the diode D2 and the thyristor SCR1 are connected to the R phase and the T phase of the main circuit 2 'of the earth leakage breaker 1, respectively. It was done.

FIG. 2 is a timing chart of the leakage breaker in FIG. 1. When a leakage current is generated in the main circuit 2 in FIG. 1, it is detected by the zero-phase current transformer ZCT, and the leakage current exceeds a set value. And the thyristors SCR1 and SCR2 are fired, and the exciting current flows from the R phase to the T phase via the thyristor SCR1, trip coil TC, and diode D1,
Thyristor SCR2 and trip coil T
C, flows through the R-phase path via the diode D2,
Full-wave rectified current I _TC flows through the trip coil TC by rectifier bridge comprised of diodes D1, D2 and the thyristor SCR1, SCR2 of Figure 1 as shown in FIG. 2, the plunger 21 of FIG. 3 is completely trip coil TC The release plate 22 of FIG. 3 pushes the engaging piece 24, the separator 29 rises to open the contact 3 of FIG. 1, and the rise of the separator 29 of FIG. 3 causes a leakage display (not shown). ) Always works.

A half-wave rectified current I _SCR1 by the diode D1 flows through the thyristor _SCR1 , and the thyristor SC
Since a half-wave rectified current I _SCR2 by the diode D2 flows through R2, each of the thyristors SCR1 and SCR2 is reliably turned off at a zero-cross of a half cycle. 2, the exciting current does not continue to flow through the trip coil TC, and there is no burning.

Therefore, the earth leakage breaker configured as described above is composed of the diode D1 and the thyristor SC connected in series.
R2 and diode D2 and thyristor SCR1 are connected in parallel to trip coil TC, and diode D1
And the connection point between the thyristor SCR1 and the diode D2 and the thyristor SCR1 are connected to the R and T phases of the main circuit 2 'of the earth leakage breaker 1, respectively. Flows, thyristor SC
Since a half-wave rectified current flows through R1 and SCR2, when a leakage current occurs, the contact 3 of the leakage breaker 1 is opened and the leakage display device is reliably operated. Thyristor SC even in the case of reverse connection
Since R1 and SCR2 are reliably turned off, the trip coil TC, the thyristors SCR1 and SCR2, and the diodes D1 and D2 are not burned.

In FIG. 3, the electric leakage display device is provided with an electric leakage display button 25, and the operation of the electric leakage breaker 27 is determined by the protrusion of the electric leakage display button 25. However, this is an example. The device is not limited to the electric leakage display button 25, and the electric leakage can be displayed by other means. Further, the circuit configuration of the earth leakage breaker 1 of FIG. 1 can be appropriately changed without departing from the object of the present invention.

[0016]

As described above, the earth leakage breaker according to the present invention has two sets of rectifiers and switching elements connected in series to the trip coil in parallel, and also has a connection point between the rectifiers and the switching elements. Are connected to the main circuits of different polarity of the earth leakage breaker, respectively.If a leakage current occurs, the contacts of the earth leakage breaker and the earth leakage display device are securely operated, and the earth leakage breaker is connected in reverse. In this case, the trip coil, the thyristor, the diode, and the like are not burned out, and have an excellent effect of high reliability.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a circuit configuration of an earth leakage breaker according to the present invention.

FIG. 2 is an explanatory diagram of a timing chart of the earth leakage breaker in FIG. 1;

FIG. 3 is an explanatory view of a tripping device for an earth leakage breaker.

FIG. 4 is an explanatory diagram of a circuit configuration of a conventional earth leakage breaker.

FIG. 5 is an explanatory diagram of a circuit configuration of a conventional earth leakage breaker.

FIG. 6 is an explanatory diagram of a timing chart of the earth leakage breaker in FIG. 4;

FIG. 7 is an explanatory diagram of a timing chart of the earth leakage breaker in FIG. 4;

FIG. 8 is an explanatory diagram of a timing chart of the earth leakage breaker in FIG. 5;

[Explanation of symbols]

1 ... earth leakage breaker, 2, 2 '... main circuit, 3 ...
Contact, D1, D2 ... diode, SCR1, SCR
2: Thyristor, TC: Trip coil, ZC
T: Zero-phase current transformer.

Claims (1)

(57) [Claims] 1. A leakage current detecting device for detecting a leakage current of a main circuit by a zero-phase current transformer, opening a contact by a trip coil, and displaying that the contact is opened by the leakage current. In the earth leakage breaker, two sets of rectification elements and switching elements connected in series are connected in parallel to the trip coil, and connection points of the rectification elements and the switching elements are respectively connected to main circuits having different polarities of the earth leakage breaker. An earth leakage breaker characterized by being connected.