JP2005135690A - Undervoltage tripping device of circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an undervoltage tripping device capable of realizing stability of attraction and releasing characteristics by switching over the coil excitation current of an electromagnet device according to the state of input time, normal operation time, and voltage shortage time. <P>SOLUTION: On the undervoltage tripping device, a coil 10b of a tripping electromagnet device 10 which is connected to a tripping device of a circuit breaker combined with a releasing spring is excited by a circuit power supply 9, and an armature 10c of the electromagnet is held in attracted state at the normal time, and when the power supply voltage is decreased, the electromagnet is released and the circuit breaker is tripped. The electromagnet coil is connected to the power supply through an electronic control circuit 11, and in the electronic control circuit, based on the power supply voltage, the coil current of the electromagnet is respectively switched over to three steps of a current Ip required for attracting the armature of the electromagnet from releasing position, a current Ih for maintaining stably the attracting state of the armature, and a minimum level current Id for attracting the armature corresponding to each state of the input time, normal state time, and voltage shortage time, and when the state of voltage shortage elapses for a prescribed time td, the electromagnet is released and the circuit breaker is tripped. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an undervoltage trip device for a circuit breaker applied as an accessory device to a circuit breaker for wiring, an earth leakage breaker and the like.

As is well known, the circuit breaker mentioned above includes an undervoltage trip device as an accessory device (optional product).
This undervoltage trip device trips the circuit breaker when the voltage of the circuit to be protected (for example, the main circuit voltage) falls below a predetermined voltage (for example, a range of 85 to 35% of the rated voltage). As an example, after connecting a tripping electromagnet combined with a release spring to a tripping device of a circuit breaker, the electromagnet coil is excited by the power source of the circuit, and against a release spring in a steady state. 2. Description of the Related Art An undervoltage trip device of a type in which an armature of an electromagnet is held in an attracted state and a circuit breaker is tripped by releasing the electromagnet when the power supply voltage is lowered is known. (For example, refer to Patent Document 1).
Here, FIG. 4 shows the configuration of a circuit breaker equipped with the undervoltage trip device. In the figure, 1 is a case, 2 is a stationary contact of the main circuit, 3 is a movable contact, 4 is an opening / closing mechanism connected to the movable contact 3, 4a is a tripping mechanism having a trip cross bar as a core, Open / close operation handle, 6 is an overcurrent tripping device, 7 is a shortage retrofitted to the accessory space (place where accessories such as voltage tripping device and undervoltage tripping device are retrofitted) defined on the surface side of case 1 A voltage trip device. In addition, 8 is a storage space for auxiliary devices such as auxiliary switches and alarm switches.

Next, a conventional undervoltage trip device is shown in FIG. In the figure, 9 is a power supply for an undervoltage trip device, 10 is an electromagnet device for tripping, and 11 is a circuit for exciting a coil of the electromagnet device 10 by the voltage of the power supply 9. Here, the power source 9 corresponds to the circuit power source to be protected, and may be taken directly from the main circuit of the circuit breaker or a power source different from the main circuit may be prepared, and the type of power source is AC, DC, etc. It varies depending on the user's request, and in the illustrated example, a DC power source is used.
The tripping electromagnet 10 includes a coil 10b wound around the yoke 10a, an armature 10c (movable iron core), a release spring 10d that urges the armature 10c in a direction to separate it from the yoke 10a, and a magnetomotive force of the coil 10b. 5 and a biasing permanent magnet 10e inserted in the magnetic path of the yoke 10a. The operating lever connected to the armature 10c is connected to the tripping mechanism 4a of the circuit breaker shown in FIG. Connected to the trip crossbar. On the other hand, the circuit 11 comprises a full-wave rectifier circuit 11a, a resistor 11b, a Zener diode 11c, and a capacitor 11d, and a coil 10b of an electromagnet 10 is connected in parallel to the capacitor 11d.

  With the above configuration, when the rated voltage is applied to the power source 9, the capacitor 11d of the circuit 11 is charged, and the electromagnet 10 is excited to energize the magnetic flux φ1 of the permanent magnet 10e. φ2 is generated, and the armature 10c is sucked against the release spring 10d. In this state, the circuit breaker can be turned on. On the other hand, when the voltage of the power source 9 decreases or is lost for some reason, the exciting current of the electromagnetic coil 10b gradually decreases due to the discharge from the capacitor 11d in the charged state, and finally the spring force of the release spring 10d is reduced. Overcoming the magnetic attractive force acting on the armature 10c of the electromagnet causes the electromagnet device 10 to release and trips the circuit breaker. In this time delay operation, in order to avoid an inadvertent trip of the circuit breaker due to a momentary interruption of the power source 9, the time from the voltage drop to the release of the electromagnet is set to about 100 msec, for example.

Apart from the above method, as disclosed in Patent Document 1, when the power supply is in a steady state at the rated voltage, the coil magnetomotive force of the electromagnet cancels the magnetic flux of the permanent magnet, and the armature is separated from the yoke by the return spring. The operating lever is retracted to the standby position, and when the voltage is insufficient and the magnetomotive force of the coil decreases, the armature is attracted by the magnetic force of the permanent magnet to trip the circuit breaker. There is also an undervoltage trip device.
JP 2000-3658 A (page 2)

Incidentally, the conventional undervoltage trip device shown in FIG. 5 has the following problems to be solved.
In other words, in order to increase the efficiency by suppressing the excitation current in the steady state of the tripping electromagnet, the permanent magnet 10e is conventionally inserted in the yoke 10a of the electromagnet 10 as shown in FIG. Since the coercive force of the magnet varies depending on the product, it is difficult to ensure stable attraction and release characteristics as the electromagnet device 10. For this reason, it has been necessary to add components such as a shunt yoke and a spacer to the permanent magnet. Although the suction characteristics are obtained, the number of parts increases and the cost increases, and problems such as the need to adjust these parts in accordance with product specifications remain.
The present invention has been made in view of the above points, and switches the coil excitation current of the tripping electromagnet apparatus according to the state of voltage shortage at the time of turning on, at the steady state, without using the permanent magnet for bias described above. It is an object of the present invention to provide a novel undervoltage trip device which is controlled to stabilize the suction and release operation characteristics and the undervoltage trip operation of a circuit breaker.

In order to achieve the above object, according to the present invention, a coil of a tripping electromagnet connected to a tripping device of a circuit breaker in combination with a release spring is excited by a power source of a circuit to be protected, and in a steady state In the undervoltage trip device that keeps the armature of the electromagnet attracted against the release spring and releases the electromagnet when the power supply voltage drops to trip the circuit breaker.
Based on the power supply voltage of the circuit, the current required to attract the electromagnet coil current from the release position to the electromagnet coil current corresponding to the undervoltage trip device when it is turned on, steady, and undervoltage , Current control means for switching the current to the armature's attracting state stably and the lowest level current for attracting the armature and releasing the electromagnet by cutting off the coil current when the voltage shortage continues for a predetermined time (Claim 1).

  Further, as a specific aspect thereof, the current control means is constituted by an electronic control circuit in which a constant voltage circuit, an average value circuit, a voltage detection circuit, a control circuit, and a drive circuit are combined, via the electronic control circuit. Then, a coil of a tripping electromagnet is connected to the power source (claim 2).

  According to the above configuration, without using a permanent magnet with a variation in coercive force, the electronic control circuit controls the trip according to the undervoltage trip device when it is turned on, at steady state, and under voltage. By switching the coil excitation current of the electromagnet in stages, a stable undervoltage trip operation can be secured and the reliability can be improved. In addition, the upper and lower limits of the undervoltage can be arbitrarily set by the control circuit according to the user's request, and the permanent magnet is not used in the tripping electromagnet device, so that the structure of the electromagnet can be simplified. can get.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 5, The description is abbreviate | omitted.
1A is a block diagram of the entire undervoltage trip device, FIG. 1B is a time chart of the operation, and FIGS. 2 and 3 are detailed circuit diagrams of the voltage detection circuit and the control circuit in FIG.
First, in FIG. 1A, the coil 10b of the tripping electromagnet 10 is connected to a power source 9 through an electronic control circuit 11 having the following circuit configuration. Here, the electronic control circuit 11 includes a constant voltage circuit 12, an average value circuit 13, a voltage detection circuit 14, a control circuit 15, and a drive circuit 16. Reference numeral 17 denotes a capacitor, and 18 and 19 denote diodes.
In the above circuit, when the rated voltage is applied from the power source 9 to the point a in the figure through the full-wave rectifier circuit 11a, the constant voltage output Vc at the output terminal b of the constant voltage circuit 12 rises as shown in FIG. The circuit is ready for operation. When the average value output at the output terminal c of the average value circuit 13 exceeds Vp (pickup voltage), the output (point d) of the voltage detection circuit 14 becomes “H”, and the resistor 14a and the capacitor 14b in FIG. The FET 16c of the drive circuit 16 in FIG. 1 (a) is turned ON only for the determined charging time (short time). As a result, the first stage coil current Ip is caused to flow through the coil 10b of the electromagnet apparatus 10 in the time zone tp of FIG. 1 (b) (Full excitation). By this full excitation, the armature 10c of the electromagnet device 10 in the released state is attracted against the release spring 10d. As a result, the circuit breaker can be turned on.

Thereafter, in the time zone th of FIG. 1 (b), the coil 10b of the electromagnet apparatus 10 is excited by restricting the current Ih in the second stage determined by the parallel connection of the resistors 16e and 16f of the drive circuit 16 to stabilize the armature 10c. The suction state is kept (steady excitation).
When the voltage of the power source 9 drops for some reason from this state and the output voltage of the average value circuit 13 becomes lower than the voltage Vr (replace voltage) of FIG. 1B, the transistor 14c in the voltage detection circuit 14 of FIG. , 14d, and 14e are both turned OFF, and the output of the voltage detection circuit changes to “L”. As a result, the FET 16b of the drive circuit 16 is turned OFF, and the coil current of the electromagnet device 10 is reduced to the third-stage current Id (the minimum level current value for attracting and holding the armature 10c). When the voltage shortage state in which the power supply voltage is lowered exceeds the discharge time td (time delay time) determined by the capacitor 15a and the resistor 15b of the control circuit 15 shown in FIG. 3, the FET 16a of the drive circuit 16 is turned off. . As a result, the exciting current stops flowing in the coil 10b of the electromagnet device 10 and the magnetic attractive force disappears. Therefore, the armature 10c is released by the spring force of the release spring 10d and trips the circuit breaker. If the power supply voltage dropped before the discharge time td elapses is recovered (instantaneous power interruption), the electromagnet device 10 returns to the normal holding state, so that the circuit breaker trips carelessly. Absent.

  In the illustrated example, the power source 9 is a direct current, but the electronic control circuit 11 in the illustrated example includes the full-wave rectifier circuit 11a and the average value circuit 13, and therefore the same applies to an AC power source. Undervoltage trip operation can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of a structure and operation | movement of the undervoltage trip apparatus by the Example of this invention, (a) is a circuit diagram of the whole apparatus, (b) is a figure showing the time chart of operation | movement. Detailed circuit diagram of the voltage detection circuit in FIG. Detailed circuit diagram of the control circuit in FIG. Configuration diagram of a circuit breaker equipped with an undervoltage trip device Configuration circuit diagram of a conventional undervoltage trip device

Explanation of symbols

7 Undervoltage trip device 9 Power supply 10 Trip electromagnet device 10b Coil 10c Armature 10d Release spring 11 Electronic control circuit 12 Constant voltage circuit 13 Average value circuit 14 Voltage detection circuit 15 Control circuit 16 Drive circuit

Claims (2)

As a circuit breaker accessory device, it is a time-delayed undervoltage trip device that trips the circuit breaker when the circuit voltage to be protected drops, and is connected to the circuit breaker trip device in combination with a release spring. The tripping electromagnet coil is excited by the power supply of the above circuit, and during normal operation, the armature of the electromagnet is attracted against the release spring. When the power supply voltage drops, the electromagnet is released and the circuit is shut off. In the one that made the vessel trip,
Based on the power supply voltage of the circuit, the current required to attract the electromagnet coil current from the release position and the armature attraction state corresponding to each of the on-state, steady-state, and undervoltage conditions. The current control means is provided with a current control means for switching the current to a stable level and a minimum level current for attracting the armature and releasing the electromagnet by cutting off the coil current when the voltage shortage continues for a predetermined time. Undervoltage trip device for circuit breakers that perform. 2. The undervoltage trip device according to claim 1, wherein the current control means is an electronic control circuit combining a constant voltage circuit, an average value circuit, a voltage detection circuit, a control circuit, and a drive circuit, through the circuit. An undervoltage trip device for a circuit breaker, wherein a coil of a tripping electromagnet is connected to a power source.

Images