CN2347297Y

CN2347297Y - Electromachine protector

Info

Publication number: CN2347297Y
Application number: CN 98240914
Authority: CN
Inventors: 张永泽
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-23
Filing date: 1998-09-23
Publication date: 1999-11-03
Anticipated expiration: 2008-09-23

Abstract

The utility model discloses an electric machine protector and relates to the engineering switch class of the three-phase electric machine. The utility model is suitable for the emergency power off device of the three-phase electric machine when the failures of phase interruption, overloading, overvoltage, overcurrent, short circuit, electric leakage, etc., are generated. The utility model aims to provide an electric machine protector with simple structure, low cost, favorable popularization and original efficiency maintaining. The utility model comprises three-phase current transformers L1, L2 and L3, three groups of rectification bridges, 7 thyristors SCR0-SCR6, an electric motor alternating current contactor RL, and an overload protection circuit. The utility model has the advantages of simple circuit and low cost.

Description

Motor protecter

The utility model relates to three phase electric machine engineering Switch, when being adapted at faults such as the phase failure, overload, overvoltage, overcurrent, short circuit and electric leakage and taking place, and the emergency power off device of three phase electric machine.

At present, when three phase electric machine meets faults such as losing phase, stall, excess load, need in time to cut off three phase supply, to avoid burn-down of electric motor.Be used to cut off the emergency protective device of three phase supply motor, utilize the thermal relay protection philosophy to make usually, but its inertia be bigger, and protector self also needs to use synchro source, so its application limitation is bigger; Also have and adopt control protective devices such as single-chip microcomputer, but structure is too complicated, cost is higher, is unfavorable for popularizing.

That the utility model purpose proposes is simple in structure, cost is low, is beneficial to popularize and still can keep the motor protecter of former available energy.

The utility model purpose is achieved in that

A kind of motor protecter is characterized in that comprising that this protector comprises threephase current transformer L1, L2, L3, three groups of rectifier bridges, 7 controllable silicon SCR 0-SCR6, motor A.C. contactor RL, and overload protecting circuit;

At three phase line places three current transformers are set respectively, the two ends of each current transformer respectively connect one group of rectifier bridge, and the output of each rectifier bridge connects its load resistance; The negative terminal of rectifier bridge output connects a controllable silicon trigger electrode again, and the output plus terminal of rectifier bridge connects this silicon controlled negative pole, and the anodal output plus terminal that connects next rectifier bridge of this controllable silicon, the rest may be inferred, and three controllable silicon SCR 1-SCR3 are the series connection shape;

The trigger electrode of SCR4 in two controllable silicon SCR 4-SCR5 that negative pole links to each other, the trigger electrode of connection bidirectional triode thyristor SCR0, the positive pole of SCR4 returns the output plus terminal that connects the first phase line A rectifier bridge; The series arm of bidirectional triode thyristor SCR0 and A.C. contactor RL line bag is connected across among two phase lines; And the trigger electrode of SCR5 connects the positive pole of SCR3, and the positive pole of SCR5 connects the common node of bidirectional triode thyristor SCR0 and contactor line bag.

Described overload is protected circuit and is connected between the 1st controllable silicon negative terminal and the 5th controllable silicon trigger electrode.

In conjunction with the accompanying drawings, further specify the utility model content.

Fig. 1 the utility model motor is lost phase protective circuit figure

Fig. 2 the utility model motor is lost and overload protecting circuit figure

Among the figure

L1-L3, current transformer M, motor SCR0-SCR6, controllable silicon Q1-Q2, triode RL, A.C. contactor

Fig. 1 is that the utility model motor is lost circuitry phase figure, and this protector comprises threephase current transformer L1, L2, L3, three groups of rectifier bridges, 6 controllable silicon SCR 0-SCR5, and motor A.C. contactor RL; Controllable silicon SCR 0 is connected with the line bag of motor A.C. contactor RL and is connected across between two phase lines, the triggering signal that SCR0 is provided by the serial connection controllable silicon SCR1-SCR3 that is serially connected between the rectifier bridge and conducting makes the contacts of contactor closure and motor rotation.

Operation principle:

When the motor operate as normal, three current transformers make the output output voltage of three rectifier bridges trigger controllable silicon SCR 1-SCR3 admittance, and finally trigger the SCR0 conducting, and three contacts of contactor RL are communicated with and the motor normal operation.Lose phase time in case arbitrary phase line takes place, cause the corresponding controllable silicon admittance not among the SCR1-SCR3 of three serial connections, then final controllable silicon SCR 0 loses triggering signal and throw off contactor three contacts, and motor power is cut off, thereby has protected motor.

Fig. 2 is that the utility model motor is lost phase, overload protecting circuit figure, threephase current transformer among the figure, three groups of rectifier bridges, controllable silicon SCR 0-SCR5 all with Fig. 1 circuit in identical, but the overload protecting circuit that has more comprises compound transistor Q1, Q2 and controllable silicon SCR 6, with and element on every side; This circuit is connected between controllable silicon SCR 1 negative terminal and controllable silicon SCR 5 trigger electrodes; The emitter-base bandgap grading output that a pair of compound transistor Q1, the Q2 of serial connection constitutes, the trigger electrode of controllable silicon SCR 6 connect the anodal of controllable silicon SCR 3 and make the voltage end of triode Q2, and the negative pole of SCR6 is made the voltage end of triode Q2; Regulate adjustable resistance VR and can regulate the effective impedance of compound transistor and current limliting.

The circuit of Fig. 2 also has defencive functions such as overload and short circuit except having the losing phase, the defencive function of Fig. 1.

Current overload and short-circuit protection circuit operation principle are as follows:

When overloads such as motor rotation blockage, excess load or short circuit, this triode Q1 admittance and Q2 end because of base voltage reduces to become rapidly, thereby chain reaction is turn-offed controllable silicon SCR 5, and final controllable silicon SCR 0 is turn-offed motor contactor three contacts are thrown off, and the motor motor is cut off.

According to the power of motor difference, adjust the different numerical value of adjustable resistance VR, can obtain the size of different stage protection overcurrent, voltage is the highest is transferred to 400 volts for overload.

The utility model advantage:

Circuit is simple, cost is low, easy popularizing.

Claims

1, a kind of motor protecter is characterized in that this protector comprises threephase current transformer L1, L2, L3, three groups of rectifier bridges, 7 controllable silicon SCR 0-SCR6, motor A.C. contactor RL, and overload protecting circuit;

2, motor protecter according to claim 1 is characterized in that described overload protecting circuit comprises compound transistor Q1, Q2 and controllable silicon SCR 6, with and element on every side; The emitter-base bandgap grading output that a pair of compound transistor Q1, the Q2 of serial connection constitutes, the trigger electrode of controllable silicon SCR 6 connect the anodal of controllable silicon SCR 3 and make the voltage end of triode Q2, and the negative pole of SCR6 is made the voltage end of triode Q2; Regulate adjustable resistance VR and can regulate the effective impedance of compound transistor and current limliting.