JPH1090313A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a shortcircuit current and drive a breaker instantaneously by detecting whether or not a next peak current exceeds a set current value after a current of a first half cycle of the shortcircuit current crosses zero and opening a contact. SOLUTION: When a shortcircuit current runs, a voltage generated at a voltage generation part 1 is divided by a voltage-dividing resistor 16. If the divided voltage is enough to turn on a thyristor 2, the thyristor 2 is turned on and the shortcircuit current passes the thyristor 2 to a connection point 7. When the thyristor 2 is turned on to let the current start to flow, a capacitor 10 is started to be charged. After the current is finished to flow, the capacitor 10 is not charged until the thyristor 2 is turned on at the second time. When the thyristor 2 is turned on at the second time and the current starts to flow, the capacitor 10 starts again to be charged. When the capacitor 10 is charged to a voltage whereby a thyristor 12 can be driven, the thyristor 12 is turned on thereby to drive a top coil 13. A contact is opened by the driving of the top coil 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current value flowing through a circuit breaker when a discharge short circuit (short short) between core wires due to melting of a cord film or the like occurs without malfunction due to overflow or inrush current. The present invention relates to a circuit breaker that instantaneously shuts off even if the current is less than an overflow or an inrush current, thereby preventing burning of a cord or the like.

[0002]

2. Description of the Related Art Hitherto, as a protection device for a cord and a load device due to an overcurrent or a short-circuit current, a bimetal or a circuit breaker using an electromagnetic coil has been used as a current detection element. However, in the circuit breaker for wiring, the instantaneous interruption current (the detection current for the interruption operation in half to several cycles) cannot be made smaller than the overflow inrush current in order to avoid a malfunction due to the overflow and the inrush current. .

[0003]

Generally, the instantaneous breaking current is set to about 10 times the rated current of the circuit breaker for wiring. However, in the case of a discharge short circuit between the core wires due to insulation deterioration of the film of the cord used to be connected to the outlet or melting of the film due to heating, the short circuit current is several tens A to 200.
Up to about A, and the short-circuit current is not a continuous sine wave but a discontinuous intermittent discharge-like current. In the case of, fire and fire could occur from the short circuit.

[0004]

The object of the present invention is to prevent malfunction by an overflow or an inrush current, and in the case of a discharge short circuit between core wires due to melting of a cord film, a short circuit current is equal to or less than an overflow or an inrush current value. However, there is an attempt to provide a circuit breaker that operates instantaneously.

[0005]

In order to solve the above problems, a circuit breaker according to the present invention is inserted into one of the poles of a circuit breaker, and converts current into a voltage and outputs the voltage. A, a thyristor A having a cathode connected to the power supply side of the current-voltage conversion means A and a gate connected to the load side, and a current-voltage conversion means B inserted into the other pole of the circuit breaker for converting a current into a voltage and outputting the voltage. A thyristor B having a cathode connected to the power supply side of the current-voltage conversion means B and a gate connected to the load side,
Diode B with anode connected to one pole of circuit breaker
And a diode A having an anode connected to the other pole of the circuit breaker, a junction A connecting the anodes of thyristors A and B to each other, and a junction B connecting the cathodes of diodes A and B to each other. Between the connection point A and the connection point B, a circuit in which a first resistor and a capacitor are connected in parallel and a second resistor are connected in series, and an end of the first resistor and the capacitor on the parallel circuit side To the connection point A, the end of the second resistor side to the connection point B side, the cathode to the connection point A,
A thyristor C having a gate connected to a connection point between the first resistor and the second resistor, and a trip coil connected between an anode of the thyristor C and a connection point B, and a mechanism for opening a contact by operation of the trip coil. Have been.

With this configuration, after the current in the first half cycle of the short-circuit current crosses zero, it is detected whether or not the next peak current exceeds a preset current value, and the contact is opened. Therefore, a circuit breaker that does not malfunction due to an overflow or an inrush current that attenuates after the peak of a half cycle crosses the zero point and that instantaneously shuts off when a discharge short circuit current occurs due to a cord accident or the like can be configured.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing an application of claim 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a voltage generator A. More specifically, a voltage generator A is disposed at one pole of the circuit breaker and generates a voltage proportional to a current flowing through a main circuit of the circuit breaker by an internal impedance of the circuit breaker. Output.

The impedance of the voltage generator A can be the impedance of a bimetal as a conventional thermal tripping element.

Reference numeral 16 in FIG. This is a resistor for dividing the voltage generated by the voltage generator A between the gate and the cathode of the thyristor A. For example, two carbon film resistors are used and a voltage equal to or higher than a predetermined value is applied to both ends of the resistor between the gate and the cathode. Occur.

Reference numeral 2 in FIG. 1 denotes a thyristor A. Through the voltage dividing resistor A, the gate of the thyristor A is connected to the power supply side of the voltage generator A, and the cathode is connected to the load side of the voltage generator A.

Reference numerals 9, 10, 14, and 15 in FIG. 1 denote charge / discharge circuits formed by resistors, capacitors, and zener diodes. The charging time constant is determined by the capacitor 10 and the resistor 15. However, it is assumed that the resistor 15 has a larger resistance value than the second resistor 11. The time constant of the discharge is determined by the capacitor 10, the resistor 15, and the first resistor 9. Here, the discharge time constant is larger than the charge time constant. Further, the Zener diode 14 has a function of making the charging voltage constant.

In FIG. 1, reference numeral 12 denotes a thyristor C. The gate of the thyristor C is connected to the connection point between the resistor 15 and the second resistor 11 in the charge / discharge circuit, and the cathode of the thyristor C is connected to the connection point A.

Reference numeral 13 in FIG. 1 denotes a trip coil. One end of the trip coil is connected to the anode side of the thyristor C, and the other end is connected to a connection point B.

Reference numeral 6 in FIG. The anode of the diode B is connected to the load side of the voltage generator B3,
The cathode of diode B is connected to node B.

The circuit according to the invention is provided with contrasting left and right poles of the circuit breaker.

The bimetal resistor B3 in FIG. 1 is a voltage generator corresponding to the bimetal resistor A1 in FIG. 1, and the voltage dividing resistor B17 in FIG. 1 is a voltage dividing resistor corresponding to the voltage dividing resistor A2 in FIG. The thyristor B4 of FIG. 1 is a thyristor corresponding to the thyristor A16 of FIG. 1, and the diode B6 of FIG. 1 is a diode corresponding to the diode A5 of FIG.

The above application will be described in detail below with reference to a waveform time chart.

FIG. 2 is a time chart when the short-circuit current is a sine wave.

When a short-circuit current flows through the circuit breaker, a voltage is generated in the voltage generator A1, and the voltage generated by the voltage dividing resistor A16 is divided. At this time, if the divided voltage is a voltage value enough to turn on the thyristor A2, the thyristor A2 turns on and the short-circuit current passes through the thyristor A2 and goes to the connection point A7.

FIG. 2 is a time chart of the current flowing to the second resistor 11 through the charging / discharging circuit in FIG. A current I1 flowing from the time when the thyristor A2 is turned on by the short-circuit current to the zero crossing;
2 from the second ON operation to the zero cross,
Is shown in FIG.

When the current I1 starts flowing, charging starts in the capacitor 10 in the charging / discharging circuit.

FIG. 2 shows a time chart of the charging voltage.

The charging is not performed from the moment when the current I1 ends to immediately before the current I2 starts to flow.

When the current I2 starts to flow, the capacitor 10 starts charging again. When the capacitor 10 is charged to a voltage at which the thyristor C12 can operate, the thyristor C12 turns on and the trip coil 13 operates.

FIG. 3 shows an overflow that flows when a light or the like is turned on.

At the time of overflow, the capacitor 10 is charged with electric charge from the first peak to the zero cross as described above.

However, since the second peak is greatly attenuated and almost equal to the normal current value from the second wave, the voltage generated in the voltage generating section is small, so The generated voltage is further reduced, and the thyristor B4 cannot be turned on. Therefore, the capacitor does not charge but discharges, and the thyristor C12
Does not operate ON. That is, since no voltage is supplied to the trip coil, the trip coil does not operate.

Since the circuit according to the present invention is configured symmetrically with respect to the left and right poles of the circuit breaker, it is possible to detect a short-circuit current of either polarity in FIGS. 1A and 1B. Can be detected and cut off in the same operation time even if the short-circuit current has a waveform starting from b.

[0031]

According to the present invention, it is possible to obtain a circuit breaker for wiring which detects a short-circuit current as shown in FIG. 2 and performs an instantaneous breaking operation, and does not perform a breaking operation as shown in FIG. Having.

Further, the structure can be simplified by using a bimetal, which is a thermal trip element of a conventional circuit breaker, as a current-to-voltage conversion means without separately providing a resistor or the like in the voltage generating section. It has the effect of being able to do it.

Further, by configuring a circuit breaker for wiring in combination with an existing overcurrent interrupting method using a bimetal, in a current region where an interrupting time does not need to be so short, such as a normal overcurrent, a current is applied by the bimetal. The present invention has an effect that a circuit breaker for wiring capable of detecting and interrupting a current can be obtained in a current region in which the operation time has to be increased due to a short-circuit current or the like due to detection and interruption.

Even if the conventional circuit breaker does not perform a breaking operation, or intermittent discharge short-circuit current generated by insulation deterioration or destruction of the cord coating which takes a long time to perform the breaking operation, the breaking is instantaneously performed without time delay. This has the effect of providing a circuit breaker that can prevent the occurrence of fire due to partial overheating of the cord.

[Brief description of the drawings]

FIG. 1 is an embodiment of the present invention.

FIG. 2 is a time chart in which a short-circuit current has a sinusoidal waveform. FIG. 3 is a time chart of a current flowing through the second resistor of FIG. 1 in FIG. 2. It is an example showing the charging voltage of the capacitor 10.

FIG. 3 is a time chart in the case of an overflow.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage generation part A 2 Thyristor A 3 Voltage generation part B 4 Thyristor A 5 Diode A 6 Diode B 7 Connection point A 8 Connection point B 9 First resistor 10 Capacitor 11 Second resistor 12 Thyristor C 13 Trip coil 14 Zener Diode 15 Resistance to determine time constant 16, 16 'Voltage dividing resistor A 17, 17' Voltage dividing resistor B 18 Contact

Claims (1)

[Claims] A voltage generator configured to combine current-voltage conversion means for converting a current into each of two circuit breaker poles and outputting a voltage, a thyristor operated by the converted voltage, and the current-voltage converter. A diode connected to the load side of the means, a charge / discharge circuit provided between the thyristor and the diode, a third thyristor operated by a constant charging voltage, and a trip coil operated by the operation of the third thyristor. A circuit breaker, wherein a mechanism is provided to open the contact by operating the trip coil by a short-circuit current.