JPS6135649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tripping circuit for a circuit breaker, and more particularly to a tripping circuit that can substantially increase the excitation current of a trip coil.

First, an example of a conventional circuit breaker tripping circuit will be described with reference to FIG.

By closing the relay contact 2, a tripping current is supplied to the trip coil 1 from the DC power source 3 via the relay contact 2, and the parallel circuit of the resistor 4 and capacitor 5, and the breaker contact 6 is tripped. At the same time, the limit switch 7 is opened in conjunction with this. In this case, in order to shorten the tripping time of the circuit breaker, it is effective to send a large current to the trip coil 1, but due to the limitation of the closing capacity of the relay contact 2, it is currently possible to 20A
degree is the acceptable limit. For this reason, it has been difficult to realize disconnection after 1 to 1.5 cycles.

In addition, a system has been proposed in which the relay contact is closed and a control current is passed through the tripping circuit, and the voltage drop across a resistor connected in series with the tripping circuit causes the thyristor to become conductive, thereby causing the tripping current to flow through the trip coil. (Japanese Patent Application Laid-open No. 1973-21267). According to this, a large tripping current is passed through the trip coil,
It is possible to shorten the tripping time of the breaker. However, thyristors are less reliable than relay contacts based on actual experience in this field, so relying only on the reliability of the thyristor for the reliability of the tripping circuit would have problems with reliability. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit breaker tripping circuit that eliminates the drawbacks of the prior art described above, reduces tripping time, and improves reliability.

To achieve this objective, the invention provides a first circuit with a mechanical contact for supplying a tripping current to the tripping coil and a second circuit comprising a switch for supplying a tripping current to the tripping coil. ,
The present invention is characterized in that when a tripping current flows through the first circuit due to the closing of the mechanical contact, the switch closes and a tripping current flows through the second circuit.

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

In FIG. 2, 1 to 7 have the same names as in FIG. 1, 8 is an impedance element connected in series to trip coil 1, 9 is a thyristor, and 10 is a second
trip coil, 11, 12 are resistors, 13, 1
4 is a capacitor, and 15 is a second DC power supply.

In such a circuit, when contact 2 is closed,
A tripping current flows from the first power source 3 through a parallel circuit of a resistor 4 and a capacitor 5, through the trip coil 1, the series impedance element 8, and the limit switch 7. This current waveform is similar to that of the conventional circuit shown in FIG. 1, and due to the presence of the capacitor 5, it becomes a waveform as shown in FIG. 3, with a peak current I _p and a steady current I _s .

The tripping time of the circuit breaker is greatly influenced by the peak current I _p , and the larger I _p is, the shorter the circuit operates. However, as described above, since the closing capacity of the relay contacts 2 is generally insufficient, there are problems such as welding of the relay contacts 2, and the peak current I _p is limited to about 7 A per unit.

In the circuit shown in FIG. 2, the series impedance element 8 is connected to the first trip coil 1, so as the trip current flows, a voltage appears across the series impedance element 8, and this voltage activates the thyristor 9. , second trip coil 1
A current flows from the second power supply 15 to the resistors 12 and 11 and the parallel capacitor 13 at 0. Therefore, magnetic flux is added by the second trip coil 10, and the opening time of the shingle breaker is significantly shortened compared to when only the conventional first trip coil 1 is used.

Note that although a reactor is best as the series impedance element 8, a resistor is also effective.
Furthermore, although there are concerns about reliability due to the use of the thyristor 9, since the connection between the series impedance element 8 and the thyristor 9 can be made in a very small space around the trip coil, surges may not enter the gate circuit of the thyristor 9. There is very little risk of it happening.
The capacitor 14 inserted into the second current circuit is
Similarly, even if a large surge voltage enters the second power supply circuit, it is desirable to make it sufficiently large so that it can be absorbed. This capacitor 14 is also effective in increasing the ability to supply current to the second trip coil.

FIG. 4 shows the current one-hour characteristics of the circuit shown in FIG. 2. When the current of curve A shown by the solid line flows through the first trip coil 1 at time t ₁ ,
At time _t2 after a short period of time has elapsed, the thyristor 9 becomes conductive, and a current of curve B shown by a dotted line flows through the second trip coil 10. The current flowing through the second trip coil 10 is unrelated to the relay contact 2, so
A current peak value I _p2 larger than the current peak value I _p1 of curve A can be caused to flow. Therefore, the overall current in the trip circuit becomes like the curve C shown by the chain line, and the tripping mechanism tripped by the tripping coils 1 and 10 operates in an extremely short time.

Further, FIG. 5 shows another embodiment of the present invention. In this circuit, the gate of the thyristor 16 is electromagnetically coupled to the trip coil 1. Now, as in the conventional circuit, when the relay contact 2 closes and a tripping current flows through the trip coil 1, a voltage is induced in the coil 7 which is electromagnetically coupled to the trip coil 1, and this is caused by the thyristor 16.
Since the voltage is applied to the gate of the first power source, it flows from the separate power supply circuit 18, through the parallel circuit of the resistor 19 and the capacitor 20, from the thyristor 16, into the trip coil 1, through the limit switch 7, and to the negative electrode side of the first power source. Since the current flowing through the thyristor 16 is independent of the closing capacity of the relay contact 2, it is possible to flow a current greater than the capacity of the relay contact 2 through the trip coil 1, thereby greatly shortening the tripping time. The second point is that the surge voltage applied to the separate power supply circuit 18 is absorbed by the capacitor 21.
This is similar to the embodiment shown in the figure.

Although the embodiments shown in FIGS. 2 and 5 have different numbers of thyristor gate circuits and trip coils, it is obvious that a combination of FIGS. 2 and 5 may be used.

Furthermore, FIG. 6 shows another embodiment in which a thyristor is not used in the second circuit. In this embodiment, the magnetic flux of the trip coil 1 is used to operate a large capacity reed switch 2.
2 is activated. This reed switch 22 is the sixth
It is replaced by the thyristor 16 shown in the figure.

In addition, in each of the above embodiments, a power source different from the power source of the conventional trip circuit is shown as the separate power source.
If it is taken from the power supply side of relay contact 2, the same power supply can be used. Furthermore, a capacitor charged by a rectifier circuit from a signal AC power source of a circuit breaker may be used as a power source.

In addition, the trip coil to which the trip current is supplied by a separate circuit may be the same as the conventional trip coil as shown in Fig. 5, or a separate second trip coil wound around the same electromagnetic core as shown in Fig. 2. The present invention is not limited to the trip coil described above, but any trip coil that excites a completely different electromagnet may be used as long as it leads to a reduction in the tripping time.

As explained above, according to the present invention, the first circuit includes a mechanical contact that supplies a tripping current that can be tripped by itself to the trip coil, and a switch that supplies the tripping current to the trip coil. A second circuit is provided, and when the mechanical contact is closed and a trip current flows through the first circuit, the switch is closed and a trip current flows through the second circuit. By passing a large tripping current through the trip coil, it is possible to shorten the tripping time of the circuit breaker. Moreover, compared to a switch that uses only a thyristor as a switch for passing the tripping current, even if a switch such as a thyristor in the second circuit becomes unable to conduct,
As usual (albeit with a relatively long trip time) due to the first circuit with reliable mechanical contacts
It is possible to reliably trip the shingle breaker, and the reliability of the shingle breaker can be improved.

[Brief explanation of the drawing]

Figure 1 is a connection diagram of a conventional circuit breaker trip circuit, Figure 2 is a connection diagram of a circuit breaker trip circuit showing an embodiment of the present invention, and Figure 3 is the same as Figure 1. 4 is a current waveform diagram of the tripping circuit shown in FIG. 2, and FIG. 5 is a current waveform diagram of the tripping circuit shown in FIG. Connection diagram: FIG. 6 is a connection diagram of a main part of a circuit breaker tripping circuit showing still another embodiment of the present invention. Explanation of symbols, 1, 10...Trip coil, 2
...Relay contact, 3,15...DC power supply, 6...
Shiya breaker contact, 8... Impedance element, 9,
16...thyristor, 17...coil.

Claims (1)

[Claims] 1. A circuit breaker trigger comprising at least one trip coil, a first circuit that supplies a trip current to the trip coil, and a mechanical contact that opens and closes the first circuit. a second circuit that supplies a tripping current to the trip coil in the tripping circuit;
a switch for opening and closing the second circuit, and when the mechanical contact closes and a tripping current flows in the first circuit, the switch closes and a tripping current flows in the second circuit. A tripping circuit for a shiya breaker, which is characterized by a flowing circuit. 2. In claim 1, an impedance element is provided in series with the trip coil, and the switch is opened by a voltage drop across the impedance element that occurs when a tripping current flows through the first circuit. A tripping circuit for a shiya breaker characterized by the following features. 3. In claim 1, a gate circuit is provided which is electromagnetically coupled to the trip coil, and the voltage induced in the gate circuit is generated when a tripping current flows through the first circuit. A tripping circuit for a shiya breaker, characterized in that the switch is closed.