JPH04259723A - Under-voltage tripping device for circuit breaker - Google Patents

Abstract

PURPOSE:To narrow the releasing range caused by unevenness of attracting force of a trip magnet and releasing force of a trip spring at low cost. CONSTITUTION:A voltage controlling circuit having a rectifier whose alternating current side is connected with a circuit voltage detecting means and direct current side is connected with a trip coil through a constant voltage diode is set between the circuit voltage detecting means and the trip coil.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an undervoltage tripping device for a breaker that protects circuits from switching on and off. An undervoltage trip device is a device that automatically releases the breaker when the circuit voltage drops, and its operating voltage is set at 20-70% of the circuit voltage by JIS and 35-70% by IEC. . [0002] FIGS. 7 and 8 show structural examples of a circuit breaker provided with an undervoltage tripping device. FIG. 7 is a longitudinal cross-sectional view, and FIG. 8 is a plan view including a partial cross section. be. The following will mainly explain the aspects related to the undervoltage tripping device. 7 and 8, the power supply side terminal 2 is placed on the insulating substrate 16.
0 and a load side terminal 21 are provided, and a power supply side terminal 2
0 is the fixed contact 17, and the load side terminal 20 is the movable contact 1.
It is connected to the. The movable contact 1 moves in the direction of arrow R in conjunction with the operating lever 22, and by moving the operating lever 22 in one direction, the movable contact 1 and the fixed contact 17 come into contact.
The circuit breaker is turned on. Also, by moving the operating lever in the other direction, the movable contact 1 and the fixed contact 17 are separated,
The circuit breaker is released. On the other hand, apart from this, a trip crossbar 2 is provided, and is located in the position shown in FIG. 7 when the breaker is turned on, that is, when the movable contacts 1 and 17 are in contact. When the trip crossbar 2 is moved in the direction of arrow P, the movable contact 1 and the movable contact are separated and the breaker is released. An undervoltage tripping device is installed at a location Q surrounded by a thick broken line. FIG. 4 is a configuration diagram including a partial cross-sectional structure of a conventional undervoltage tripping device, in which a yoke 14 is provided inside a base 3, and a trip coil wound cylindrically inside the yoke 14. 13 and a ring-shaped permanent magnet 10 magnetized in the radial direction are provided in parallel, and the yoke 1
4, a magnetic pole 9A provided inwardly inside one end of the yoke 14, and a ring-shaped magnetic pole 9B provided at the other end form a magnetic path to attract the cylindrical movable iron piece 8A. There is. Hereinafter, a combination consisting of the trip coil 13, the permanent magnet 10, the yoke 14, the magnetic poles 9A, and the magnetic poles 9B will be referred to as a trip magnet 15. A shaft 8B is attached to the central axis of the movable iron piece 8A to form a plunger 8. The end surface of the shaft 8B on the side opposite to the movable iron piece 8A is formed with a somewhat wide surface, and the trip lever 4, which rotates around the pin 11, is attached to the spring 7 on this surface.
It is crimped by. Anti-pin 1 of trip lever 4
The one end faces the trip crossbar 2 shown in FIGS. 7 and 8. The end of the trip lever 4 on the pin 11 side is connected via a movable lever 6 to a pull-back lever 5 that rotates about the pin 12 as a central axis. Trip coil 13 is connected to circuit voltage detection means 25 . As the circuit voltage detection means 25, a resistive voltage divider connected to the circuit is usually used, but if the voltage is low, the terminal of the trip coil may be directly connected to the circuit. The operation of the conventional undervoltage trip device will be described below with reference to FIGS. 5 and 6 in addition to FIG. 4. FIG. 4 shows a state in which the trip coil 13 is excited by the voltage applied from the circuit voltage detection means 25 and attracts the plunger 8, that is, the plunger 8 is moving to the right, and the trip lever 4 is It is rotated counterclockwise. Here, when the breaker is turned on, the trip crossbar 2 comes to the position shown in FIG. 4. In this state, the circuit voltage decreases and when it reaches the operating voltage, the attraction force F1 of the trip magnet 15 is increased by the release force F2 of the trip spring 7 attached to the trip lever 4.
becomes smaller, the plunger 8 is released and moves to the left, and the trip lever 4 rotates clockwise. At this time, the trip lever 4 moves the trip crossbar 2 to the left, that is, in the direction of arrow P, thereby releasing the breaker. FIG. 5 shows this state. At this time, the movement of the trip crossbar 2 causes the pull-back lever 5, which rotates around the pin 12 as a central axis, to rotate counterclockwise, and this movement is applied to the trip lever 4 by the connecting rod 6, causing the trip lever 4 to move counterclockwise. Rotate clockwise. When the circuit voltage is restored, the attractive force of the trip magnet 15 becomes greater than the repulsive force of the trip spring 7, attracting the plunger 8 and moving it to the right, and the breaker becomes ready to be closed again. FIG. 6 shows this state. FIG. 3 shows the operating characteristics of the conventional undervoltage tripping device shown in FIG.
The detection voltage V1 is a voltage proportional to the circuit voltage. The vertical axis indicates the attraction force F1 of the trip magnet 15 and the release force F2 of the trip spring 7. When the circuit voltage drops below the rated value and the attraction force F1 of the trip magnet 15 becomes smaller than the release force F2 of the trip spring 7 (point T0 in FIG. 2), the plunger 8 is released and the breaker is released. However, there are variations in the trip magnet 15 and the trip spring 7 as shown in the figure, and the current situation is that the release range of the circuit breaker expands to the range T1 to T2. [0006] In the above-mentioned undervoltage tripping device for a circuit breaker, the release range greatly expands due to variations in the attraction force of the trip magnet or the release force of the trip spring, and in some cases, J.I.
It exceeds the S or IEC standards. Furthermore, even if the standard is not exceeded, it is extremely important for the protection function that the range of release is small. However, minimizing variations in the attraction force of the trip magnet or the release force of the trip spring requires increasing the precision of the machine or increasing the size of the device, which significantly increases costs. An object of the present invention is to provide an undervoltage tripping device that is low in cost and has a small release range. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a circuit voltage detection means, a trip coil connected to this means, and a voltage that is attracted by the electromagnetic force of the trip coil. and a trip lever that operates in conjunction with the plunger to drive a trip crossbar that releases the circuit breaker. When the plunger is released, the trip lever is moved in conjunction with the plunger to drive the trip close lever to release the breaker, or a circuit voltage detection means;
A trip coil connected to the means, a permanent magnet provided in parallel with the trip coil, a plunger attracted by the electromagnetic force of the trip coil and the magnetic force of the permanent magnet, and a plunger that is interlocked with the plunger. and a trip lever that drives a trip crossbar that releases the breaker, and when the circuit voltage drops below a predetermined value, the plunger is released due to a decrease in the electromagnetic force of the trip coil, and the plunger is interlocked with the plunger. In the undervoltage tripping device for a breaker, which drives the trip crossbar and releases the breaker by the movement of the trip lever, an AC side is connected to the circuit voltage detection means between the circuit voltage detection means and the trip coil. A voltage control circuit including a rectifier connected to the trip coil and having a DC side connected to the trip coil via a constant voltage diode is provided. [Operation] In the undervoltage tripping device for a circuit breaker of the present invention, between the circuit voltage detection means and the trip coil,
Since the voltage control circuit includes a rectifier whose AC side is connected to the circuit voltage detection means and whose DC side is connected to the trip coil via a constant voltage diode, the voltage applied to the trip coil is equal to the detection voltage. When the voltage is higher than the constant voltage of the constant voltage diode, the voltage changes rapidly in response to changes in the detected voltage. Since the release point of the circuit breaker is determined at a point where the voltage rapidly changes, the range of release voltage determined by variations in the attraction force of the trip magnet and variation in the release force of the trip spring is reduced. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially sectional view showing an embodiment of an undervoltage tripping device for a circuit breaker according to the present invention. This embodiment is different from the conventional example shown in FIG. A voltage control circuit 36 including a rectifier 32 connected to the voltage control circuit 13 is provided. FIG. 2 shows the operating characteristics of the undervoltage tripping device for a circuit breaker according to the present invention shown in FIG. . The vertical axis indicates the attraction force F1 of the trip magnet 15 and the release force F2 of the trip spring 7. The trip coil 13 is provided with a voltage control circuit 36.
A voltage obtained by subtracting the voltage of the constant voltage diode from the detection voltage V1 is applied. That is, while the detected voltage V1 is lower than the constant voltage value Vd of the constant voltage diode, almost no voltage is applied to the trip coil 13, but when the detected voltage V1 increases and exceeds the constant voltage value Vd, the voltage V1 -
The differential voltage of Vd is applied to the trip coil 13, and a rapidly increasing voltage is applied to the trip coil 13. In other words, the detection voltage V1 is the constant voltage value Vd
When the voltage is lower than the constant voltage value Vd, the voltage of the trip coil 13 is approximately 0, and when it is higher than the constant voltage value Vd, the voltage changes rapidly in response to changes in the detection voltage V1. Therefore, when the detection voltage V1 is lower than the constant voltage value Vd, the attractive force F1 of the trip magnet 15 is a substantially constant attractive force due to the permanent magnet 10, but when the detected voltage V1 exceeds the constant voltage value Vd, the permanent magnet 1
The attraction force between the trip coil 13 and the trip coil 13 results in an attraction force that changes rapidly in response to changes in the detected voltage. If the release force of the trip spring 7 is set so that the release point of the breaker falls within the range of this rapidly changing attraction force, the release range due to variations in the attraction force of the trip magnet and variations in the release force of the trip spring will be reduced. That will happen. Note that in FIG. 1, a surge absorber 31 provided on the AC side of the rectifier 32 protects electronic components used in the voltage control circuit 36. In addition, the current limiting resistor 33 and the smoothing capacitor 34 provided on the DC side of the rectifier 32 constitute a smoothing circuit, which reduces ripples in the DC output voltage of the rectifier 32 and makes the operation of the voltage control circuit 36 more stable. This results in a more reliable device. In the embodiment shown in FIG. 1, the trip magnet 15 is provided with a permanent magnet 10 and a trip coil 13, but as is clear from the principle, only the trip magnet 15 is sufficient. However, by using a permanent magnet in combination, the trip coil can be made smaller and a smaller, lower-cost device can be obtained. In this case, as the share of the attraction force of the trip coil decreases, the change in the attraction force of the trip magnet in response to changes in the detected voltage becomes smaller, and the release range of the breaker increases. Therefore, the present invention is more effective in the case of an undervoltage tripping device using a trip magnet combined with a permanent magnet. [0013] According to the present invention, in claims 1 and 2, the AC side is connected to the circuit voltage detection means between the circuit voltage detection means and the trip coil, and the DC side is connected to the circuit voltage detection means through a constant voltage diode. By providing a voltage control circuit with a simple circuit configuration including a rectifier connected to a trip coil, the open range of the breaker is reduced, so the protection function of the breaker can be improved at low cost. In particular, as shown in claim 2, it becomes possible to use a small trip magnet in combination with a permanent magnet having a large release range, and it becomes possible to manufacture a small and inexpensive undervoltage tripping device. In claim 3, since a surge absorber is provided on the AC side of the rectifier of the voltage control circuit and a smoothing circuit is provided on the DC side, electronic components used in the voltage control circuit are protected and the operation of the voltage control circuit is The result is a more stable and more reliable device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram including a partially sectional structure showing an embodiment of an undervoltage tripping device for a circuit breaker according to the present invention.

[Fig. 2] Operation characteristic diagram of the undervoltage trip device of the breaker of the present invention shown in Fig. 1

[Figure 3] Operating characteristics diagram of the conventional breaker undervoltage tripping device shown in Figure 4

[Fig. 4] A configuration diagram including a partial cross-sectional structure showing a conventional example of a conventional undervoltage tripping device for a circuit breaker.

FIG. 5 is a configuration diagram including a partially cross-sectional structure for explaining the operation of the conventional breaker undervoltage tripping device shown in FIG. 4;

FIG. 6 is a configuration diagram including a partially cross-sectional structure for explaining the operation of the conventional breaker undervoltage tripping device shown in FIG. 4;

[Fig. 7] Cross-sectional view showing an example of a breaker equipped with an undervoltage trip device

[Fig. 8] A plan view including a partial cross section of the breaker shown in Fig. 7.

[Explanation of symbols]

2 Trip crossbar 4 Trip lever 7 Trip spring 8 Plunger 10 Permanent magnet 13 Trip coil 25 Circuit voltage detection means 31 Surge absorber 32 Rectifier 33 Current limiting resistor (of smoothing circuit) 34 Smoothing capacitor (of smoothing circuit) 35
Constant voltage diode 36 Voltage control circuit

Claims (3)

[Claims] Claim 1: A circuit voltage detecting means, a trip coil connected to the means, a plunger attracted by the electromagnetic force of the trip coil, and a trip crossbar interlocked with the plunger to release a breaker. When the circuit voltage drops below a predetermined value, the plunger is released due to the decrease in the electromagnetic force of the trip coil, and the movement of the trip lever in conjunction with the plunger causes the trip lever to be driven. In the undervoltage tripping device for a circuit breaker that drives a breaker to release the circuit breaker, an AC side is connected to the circuit voltage detection means and a DC side is connected to the circuit voltage detection means via a constant voltage diode between the circuit voltage detection means and the trip coil. An undervoltage tripping device for a circuit breaker, comprising: a voltage control circuit including a rectifier connected to the trip coil. 2. A circuit voltage detecting means, a trip coil connected to the means, a permanent magnet provided in parallel with the trip coil, and a voltage that is attracted by the electromagnetic force of the trip coil and the magnetic force of the permanent magnet. and a trip lever that operates in conjunction with the plunger to drive a trip crossbar that releases the circuit breaker. When the plunger is released, the trip crossbar is driven by the movement of the trip lever in conjunction with the plunger, and the circuit breaker undervoltage tripping device releases the breaker. An undervoltage tripping device for a circuit breaker, characterized in that a voltage control circuit is provided with a rectifier whose AC side is connected to the circuit voltage detection means and whose DC side is connected to the trip coil via a constant voltage diode. . 3. In the undervoltage tripping device for a circuit breaker according to claim 1 or 2, a surge absorber is provided on the AC side of the rectifier provided in the voltage control circuit, and a smoothing circuit is provided on the DC side. Features: Undervoltage tripping device for circuit breaker.