JPS6130912A - Circuit 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 [Field of Application of the Invention] The present invention relates to a circuit breaker using a magnetic trip device as an actuator for tripping a disconnection mechanism.

[Summary of the invention]

In a circuit breaker that detects a fault current using a current transformer and an electronic circuit, the magnetic flux of the holding magnet is constantly used to convert the electric signal from the electronic circuit into the mechanical energy necessary for the disconnection operation of the connecting mechanism. A magnetic trip device is generally used in which a movable piece is attracted to a magnetic pole by a demagnetizing action of a trip coil, and the movable piece is released by a demagnetizing action of a trip coil to trip a cutoff mechanism.

In order to operate this magnetic tripping device again after a tripping operation, the movable piece must be returned from the released state to the attracted state by an external force. Conventionally, the resetting of this magnetic trip device has been performed using K as shown in Japanese Utility Model Publication No. 58-24864.

This is often done in conjunction with the reset operation of the operating handle when the circuit breaker is re-closed, but it is also possible to take out the state change when resetting the magnetic trip device as an electrical signal and control the attached devices of the circuit breaker. It was not used for.

[Purpose of the invention]

An object of the present invention is to utilize the back electromotive force generated in the tripping coil when resetting the magnetic tripping device.
An object of the present invention is to provide a circuit breaker that allows easy and reliable control of attached devices related to resetting a magnetic trip device. In a circuit breaker equipped with a magnetic trip device that attracts a piece to a magnetic pole and releases the movable piece by the demagnetizing action of a tripping coil to trip and operate the interrupting mechanism, the movable piece changes from a released state to an adsorbed state. The circuit breaker is characterized in that it is equipped with a signal transmission means for controlling an accessory device of the circuit breaker using the back electromotive force generated in the closing coil as a signal source in the process of K (1#I).

[Embodiments of the invention]

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

In Figure 1, the current flowing in the protected circuit IK is transferred to the current transformer 2.
When an overcurrent is detected by the overcurrent tripping circuit 8, a signal is sent to the magnetic tripping device 4 after a delay time corresponding to the current value.
Breaking mechanism 51 - The configuration for tripping is the same as the general configuration of a circuit breaker equipped with a magnetic four-way disconnect device. The overcurrent tripping circuit 8 uses the secondary output current of the current transformer 2 as its power source, similar to that disclosed in Japanese Patent Laid-Open No. 57-170028.

The magnetic trip device 4 is configured as shown in FIG.

Composed of a tripping coil 6, a holding magnet 7, a movable piece 8, a magnetic pole 9, and a yoke lO1 spring 11. Normally, the magnetic flux of the holding magnet 7 causes the movable piece 8 to move against the spring 11 to the magnetic pole 9. Although it is attracted, when the excitation current flowing through the trip coil 6 reaches the operating current value, the movable piece 8 is released due to the demagnetizing effect of the trip coil 6, which generates a magnetic flux in the opposite direction to the magnetic flux of the holding magnet 7. Then, the shutoff mechanism 5 shown in FIG. W1 is mechanically tripped and operated.

In such a magnetic tripping device, when the movable piece 8 is returned from the released state to the attracted state (3!), a back electromotive force is generated in the tripping coil 6 due to a rapid change in the permeance of the magnetic circuit.According to experiments, , as shown in Figure 8, the trip coil of the magnetic trip device (number of turns: 4000T)
, DC resistance: 365Ω) 6, and when the movable piece 8 is returned from the released state to the attracted state, a current i flows in the direction of the arrow due to the above-mentioned back electromotive force. It has been found that when a light emitting diode having the forward current-forward voltage characteristic shown in FIG. 4 is used, the current waveform is K as shown in FIG. 5, and a current sufficient to light the light emitting diode 12 flows.

FIG. 1 shows an example in which this phenomenon is utilized to control a voltage disconnection device 18, which is an accessory device of a circuit breaker. The voltage trip device 18 is an accessory device for external operation, and when the switch 15 installed at equal pressure in the control center (the manual switch is a relay contact) is turned on, the external power source 14 also turns on the electronic circuit 16 for preventing coil burnout. An excitation current flows through the pull-out coil 6 of the magnetic pull-out device 4, thereby releasing the movable piece 8 shown in FIG. 2, and mechanically tripping the interrupting mechanism 5. Therefore, the magnetic trip device 4 is used both for voltage trip and overcurrent trip.

In this embodiment, the back electromotive force generated in the trip coil 6 when the magnetic trip device 4 is reset is transferred to the voltage trip device 1.
8, the light emitting diode 12 is used as a signal transmission means, and the light emitting diode 12 is connected in parallel to the coil 6 so as to be in the forward direction with respect to the current iK caused by the counter electromotive force. It is connected. The diode 17 connected in series to the light emitting diode 12 is for preventing the light emitting diode 12 from being damaged by reverse voltage when the tripping coil 6 is excited.

Next, the operation of the light emitting diode 12 will be explained with reference to FIG.

FIG. 6 is a detailed diagram of the electronic circuit 16 for preventing coil burnout of the voltage trip device. A coil burnout prevention electronic circuit 16 built into the circuit breaker includes the light emitting diode 12 and diode 17, a rectifier 18, and a capacitor 19.2.
0. Resistors 21-26, Zener diodes 27.28, transistors 29.80. The phototransistor 81 is composed of a light emitting diode 1 and a phototransistor 81.
The light receiving element is combined with the light receiving element 2.

When the switch 15 is turned on, a current flows from the external power supply 14 through the rectifier 18 - resistor 26 - trip coil 6 - transistor 8 - rectifier 18, and the magnetic trip device 4
is operated to trip the shutoff mechanism 5.

On the other hand, the voltage at point A rises according to the time constant of the resistors 21 and 22 and the capacitor, and the voltage increases across the Zener diode 28.
When the 0 zener voltage value is exceeded, the transistor 29 turns on,
Transistor 80 is turned off.

This allows the current to flow through the rectifier 18 - resistor 25 - transistor 29 - rectifier 18, and the current passing through the trip coil 6 is cut off, thereby preventing burnout of the short time rated trip trip coil 6. The above are the original functions of the coil burnout prevention electronic circuit 16.

next! When the operating handle (not shown) is moved to the reset position in order to reinsert the new mechanism 5, the movable piece 8 of the magnetic tripping device 4 is returned from the released state to the attracted state in the process of being unable to be pulled. The light emitting diode 12 lights up momentarily due to the counter electromotive force generated in the coil 6. This light turns on the phototransistor 81 and the capacitor 20
When the magnetic trip device 4 is reset with the switch 15 in the on state in order to discharge the electric charge of flow, movable piece 5
, and the shutoff mechanism 5 cannot be turned on again. That is, by adding the light emitting diode 12 and the phototransistor 81 to the coil burnout prevention electronic circuit 16, when the switch 15 of the voltage tripping device is in the on state, the interrupting mechanism 5 is erroneously turned on again. This provides a new function that can prevent accidents and improve safety.

The above is an example in which the present invention is applied to a circuit breaker equipped with a voltage cut-off device, but the present invention can also be applied to other accessory devices, such as a circuit breaker equipped with an operation indicator for each accident cause. can. In other words, when the drive coil of the target type display is excited by the operation signal of the overcurrent string disconnection circuit and the operation is displayed according to the cause of the accident, such as overload or short circuit,
Normally, the indicator is manually reset when the disconnector is turned on again, but the counter electromotive force of the tripping coil 6 generated when resetting the magnetic tripping device described above is used to reset the indicator's return coil Km. If direct driving is not possible, use the light emitting diode 12. as described above. By amplifying the current caused by the counter electromotive force using the phototransistor 81 and passing it through the recovery coil, the display can be automatically reset, and if it stings, the trouble of manual reset can be saved, and the manual reset can be forgotten. It is possible to prevent a situation in which operation display cannot be performed when an fcfc accident occurs next time.

〔Effect of the invention〕

According to the present invention, the back electromotive force generated in the trip fill in the process of returning the movable piece of the magnetic trip device from the released state to the attracted state is used as a signal source for controlling the attached device. You can easily and reliably control the attached devices for each strain connected to the magnetic tripping device (Nori Sera) K11ml without being subject to installation space constraints like a signal switch that mechanically detects the movement of a movable piece. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a side sectional view of a magnetic tripping device, and FIG. 8 is a test circuit diagram for lighting a light emitting diode using the back electromotive force of a tripping coil.
Figure 4 is a forward current-forward voltage characteristic diagram of a light emitting diode, Figure 5
This figure is a waveform diagram of the current flowing through the circuit of FIG. 8, and FIG. 6 is a detailed diagram of the electronic circuit for preventing coil burnout in FIG. 1. 4: lil pull-out device, 5: cutoff mechanism, 6: draw-out coil, 7: holding magnet, 8: Ij moving piece, 9: m pole,
12z signal transmission means, ]8: Attached equipment.

Claims (1)

[Claims] In a circuit breaker equipped with a magnetic trip device that normally attracts a movable piece to a magnetic pole by the magnetic flux of a holding magnet, and releases the movable piece by the demagnetizing action of a tripping coil to trip and operate a interrupting mechanism, A circuit breaker characterized by comprising a signal transmission means for controlling an accessory device of the circuit breaker using a back electromotive force generated in the tripping coil as a signal source in the process of the movable piece returning from a released state to an adsorbed state. vessel.