JPH0578146U - Current limiting circuit breaker - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a current limiting circuit breaker that does not require a special commutation mechanism and can flow a large current when energized. [Configuration] Switch with contact, semiconductor switch, current limiting resistance Are connected in parallel, the fault current is diverted to the semiconductor switch by opening the contact, and then the semiconductor switch is turned off.
A means is provided for rectifying the current to flow into the current limiting resistance.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a current limiting circuit breaker.

[0002]

[Prior Art]

 A first example of a conventional current limiting interrupter will be described with reference to FIGS. 2 and 3. 2 is a circuit diagram of the current limiting interrupter, and FIG. 3 is an explanatory diagram of the commutation mechanism of FIG.

As shown in FIG. 2, the current limiting circuit breaker of this example is configured by connecting a current transformer 1 and a circuit breaker 8 in series with a parallel circuit of a high speed switch 3 and a current limiting resistor 6. To be done.

The operating principle of this current limiting interrupter will be described. When a short-circuit accident occurs, a large short-circuit current flows, but before the 100% short-circuit current flows, the current transformer 1 and the fault current detector 2 make an error at the current rising part of the order of several times the normal current. Is detected, the operation mechanism unit 4 opens the high-speed switch 3. An arc 7 is generated between the contacts during the opening of the high-speed switch 3, and the non-linear resistance and the current limiting resistance 6 due to the arc 7 are connected in parallel. The non-linear resistance of the arc 7 connected in parallel and the resistance value of the current limiting resistor 6 are out of balance, the non-linear resistance of the arc 7 increases, and finally the resistance value becomes infinite. The flow shifts to 6 and the commutation ends. The fault current is limited by the current limiting resistance and decreases to about 2 KA when the normal fault current is 20 KA, for example. The circuit breaker 8 is provided for breaking the circuit if the accident does not recover while the current limiting action is being performed.

Explaining the extinction of the arc in the current limiting circuit breaker of this example, the current limiting resistance 6 is normally on the order of ohms, whereas the arc resistance is on the order of a few tenths thereof. During commutation, the current continues to flow mainly through the non-linear resistance of the arc 7. It is not easy to extinguish the arc once generated in this way, and a very special commutation mechanism is provided in the current limiting resistor 6 itself to smoothly commutate.

An example of the special commutation mechanism is shown in FIG. The current limiting resistance 6 is formed in a fan shape as shown in the figure, and the arc 7 generated by opening the contact of the high speed switch 3 moves in the direction of the arrow shown by the electromagnetic force of its own, and the arc is formed at the fan-shaped resistor 6. 7 moves along the resistor 6 while spreading in a fan shape. As the arc spreads, the resistance value of the resistor 6 is inserted into the circuit, the resistance value of the circuit increases, and finally the arc 7 is extinguished. Thus, the commutation mechanism of this example had to use a special and large one.

Next, a second example of the conventional current limiting interrupter will be described with reference to FIG. FIG. 4 is a circuit diagram of the second conventional example.

In this example, a semiconductor switch 12 is used in place of the high-speed switch, a current limiting resistor 6 is connected in parallel with it, and a circuit breaker 8 is connected in series to this parallel connection body. When an abnormality is detected, the current transformer 1 and the fault current detector 2 detect the abnormality, the control unit 15 turns off the semiconductor switch 12, and the current is commutated to the current limiting resistor 6 without arc. This example is superior to the first conventional example in that no arc is generated, but the semiconductor switch 12 has a large loss, and therefore has a drawback that a large current cannot flow during normal energization.

[0009]

[Problems to be solved by the device]

 As described above, the conventional current limiting circuit breaker requires a very special and large commutation mechanism for commutation, or cannot carry a large current if commutation is easy. There was a drawback.

An object of the present invention is to provide a current limiting circuit breaker that does not require a special commutation mechanism and can flow a large current when normally energized.

[0011]

According to the present invention, a switch having a contact, a semiconductor switch, and a current limiting resistor are connected in parallel, and a fault current is diverted to the semiconductor switch by the opening of the contact. A means to turn off the semiconductor switch and commutate the current to the current limiting resistance is adopted.

[0012]

[Action]

 By means of the above means, the current limiting interrupter of the present invention energizes with mechanical contacts, so a large current can flow during normal energization, and in the event of a short-circuit accident, commutation from the contacts to the semiconductor switch occurs. Therefore, the arc is extinguished quickly, and no special commutation mechanism is required.

[0013]

【Example】

 The configuration of the present invention will be described with reference to the embodiment shown in FIG. FIG. 1 is a circuit diagram of this example.

In the figure, a current transformer 1, a high speed switch 3 and a breaker 8 are connected in series. The current limiting resistor 6 and the semiconductor switch 12 are connected in parallel with the high speed switch 3. The semiconductor switch 12 is composed of a GTO, a protection circuit, L and C elements for smoothing commutation, etc., but details thereof are omitted.

When a short-circuit accident occurs, a large short-circuit current flows, but before the 100% short-circuit current flows, the current transformer 1 and the fault current are detected at the current rising portion of the order of several times the normal current. An abnormality is detected by the device 2, and two signals 10 and 11 are simultaneously output. One signal 10 is input to the semiconductor switch 12 via the control unit 15 to turn on the semiconductor switch 12. The other signal 11 is input to the operating mechanism section 4 for the high speed switch 3 to open the high speed switch 3.

The semiconductor switch 12 obtains an ON signal before the contacts of the high-speed switch 3 are opened. However, since the inter-electrode resistance of the high-speed switch 3 is about several tens of μΩ, even if a current of several 1000 A flows, the voltage of 0. Only 1V order voltage is generated. On the other hand, since the ON voltage of the semiconductor switch 12 is on the order of several V, the semiconductor switch 12 does not commutate at this time. After that, when the high-speed switch 3 is opened, an arc is generated between the poles, and the arc voltage between the poles is on the order of several hundreds V, which exceeds the on-voltage of the semiconductor switch 12, so commutation to the semiconductor switch 12 occurs. Is done. As a result, the arc voltage is reduced to the on-voltage of the semiconductor switch 12 on the order of several V, and the voltage for maintaining the arc cannot be obtained, so the arc is extinguished. As a result, the arc extinguishes quickly without growing.

When the commutation of the current in the semiconductor switch 12 is completed, the current of the high-speed switch 3 becomes 0. Therefore, the current is detected by the second current transformer 13 and the arc current detector 14, and the control is performed. An off signal is output from the unit 15 to the semiconductor switch 12. When the semiconductor switch 12 is turned off, the current is all commutated to the current limiting resistor 6 without arc. Thus, the commutation to the current limiting resistor 6 is performed without using a special commutation mechanism. The operation of the circuit breaker 8 is similar to that of the conventional case, and therefore its explanation is omitted.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. is there. For example, the example of using a high-speed switch as a contact switch has been explained, but a high-speed switch achieves the most favorable effect, but a normal switch can also achieve the desired effect. It is a thing.

[0019]

[Effect of the device]

 According to the present invention, when the short-circuit accident occurs, the commutation to the current limiting resistance is performed quickly, and the arc can be easily extinguished, so that no special commutation mechanism is required. In addition, since normal energization is performed by mechanical contacts, it is possible to pass a large current.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional first example.

FIG. 3 is an explanatory view of a commutation mechanism used in FIG.

FIG. 4 is a circuit diagram of a second conventional example.

[Explanation of symbols]

1 ... Current transformer, 3 ... High-speed switch, 6 ... Current limiting resistance, 8 ... Breaker, 12 ... Semiconductor switch.

Claims (1)

[Scope of utility model registration request] 1. A current limiting circuit breaker in which a contact switch and a current limiting resistor are connected in parallel, a semiconductor switch is connected in parallel to the parallel connection body, and the semiconductor switch is turned on by detecting a fault current, and at the same time, the semiconductor switch is turned on. A current limiting breaker provided with means for opening a contact of a contact switch and detecting that the current of the contact switch has become 0 to turn off a semiconductor switch.