CN2472388Y - Passive protector for motor - Google Patents

Abstract

The utility model relates to a passive motor protector, in particular to the protection of abnormal states such as break phase and overload of three-phase motors. The utility model is characterized in that an inner working power supply is provided by induction electromotive force of a three-phase current detection coil after rectifying and wave-filtering; and a no-contact AC electronic switch is made as an output. The utility model has the advantages of no limitation of working voltage grade, no sparkle during working process and long service life.

Description

Passive motor protector

The utility model relates to a kind of passive motor protector, especially to the protection of abnormal condition such as do not weigh of the phase failure, overload and the three-phase of threephase motor.Fuse shields in the time of can only being short-circuited fault in the supply line of motor as a kind of protection component of motor, reduces the expansion of fault coverage, but to cause burning of motor to protect because of the open phase fault in the power supply circuits; Though thermal relay is applied in the overload protection of motor, function singleness, sensitivity is low, error is big, unstable properties, and the situation of therefore burning motor happens occasionally, and influence is produced and caused damage.A large amount of at present motor protectors that use need provide power supply and adopt the electromagnetic actuator that the contact is arranged, and belong to " active " design.This class protector is in long-term energising; be subjected to the interference that produces because of voltage ripple of power network easily; and the spark that the contact of the electromagnetic actuator of protector is easy to generate miscellaneous equipment in the transfer process after the load on tape disturbs; and a kind of protector of electric pressure can only be applicable to a kind of circuit of electric pressure, and the restriction that is subjected to mechanical endurance and electric life service life of the electromagnetic actuator of contact is arranged simultaneously.

The purpose of this utility model is to provide a kind of be not subjected to no-spark, long passive motor protector of life-span in the restriction of operating voltage grade in the circuit, applied widely, stable and reliable for performance, the course of work for the defective that overcomes above-mentioned prior art.

In order to achieve the above object; solution of the present utility model is: passive motor protector still comprises the three-phase current detection coil; comparator circuit; amplification driving circuit and final controlling element; the output of three-phase current detection coil is connected with the comparator circuit input; comparator circuit output is amplified output through amplification driving circuit and is controlled the A.C. contactor that is used with motor protector; the main contact of A.C. contactor is connected in the motor three phase mains inlet wire and controls motor power; described comparator circuit power supply is provided behind the rectification circuit rectifying and wave-filtering by induced electromotive force on the three-phase current detection coil, and amplification driving circuit is made of contactless electronic AC switch circuit.

Adopted the passive motor protector of such scheme; the power supply of the comparator circuit that it is inner is to be provided behind rectifying and wave-filtering by the induced electromotive force on the three-phase current detection coil; irrelevant with the operating voltage of power supply; and its amplification driving circuit is contactless electronic AC switch circuit; can contactless mode control the A.C. contactor that is used with it, reach and be not subjected to operating voltage restriction, applied widely, stable and reliable for performance, course of work no-spark, long purpose of life-span.

The utility model is further elaborated and provides embodiment below in conjunction with accompanying drawing.

Fig. 1 is the utility model embodiment electrical schematic diagram.

As shown in Figure 1, L1, L2, L3, be three-phase circuit stream magnetic test coil, the three-phase power line of motor passes from L1, L2, L3 respectively, the positive pole of diode V1, V2, V3 is connected with the end of electric current detecting coil L1, L2 and L3 respectively, negative pole is connected to each other and constitutes positive source together, the other end of electric current detecting coil L1, L2 and L3 is connected to each other and constitutes power cathode together, and filter capacitor C1 is connected between the power supply positive and negative electrode; Described contactless electronic AC switch circuit 2 is by resistance R 1; R2; R3 triode V4; V5 and controllable silicon V6 and bridge rectifier 3 constitute; bridge rectifier 3 dc output ends just; be connected to controllable silicon V6 between the negative pole; triode V4 collector electrode is received dc power anode by resistance R 1; triode V5 base stage is connected with triode V4 collector electrode; triode V5 collector electrode one tunnel also is connected to dc power anode through resistance R 3; another road is connected with controllable silicon V6 trigger electrode; the emitter of triode V4 and V5 is received dc power cathode simultaneously; triode V4 base stage is connected with comparator circuit 1 output; bridge rectifier 3 ac input circuits are exported as passive motor protector, and contactor KM actuating coil seals in the ac input circuit of bridge-type current circuit 3.

The moment of starting working, the V4 base stage is a high level, V5 ends, make the V6 conducting, A.C. contactor KM coil is energized, the main contact closure, motor adds that three phase mains normally starts, induced current and induced electromotive force among L1, L2, the L3 provides dc supply to comparator behind rectifying and wave-filtering at this moment, simultaneously with the normal run signal input comparator of detected motor, export the conducting that a high level is kept V4 and V6 after relatively, ac contactor coil KM keeps being energized state, normally moves thereby keep motor.When abnormal condition such as the phase failure, overload, three-phase imbalance occurring, L1, L2, L3 be detected signal input comparator, output low level after relatively; making the V4 base stage is low level; V4 ends, and the V5 base stage is a high level, makes the V5 conducting; the collector electrode of V5 is by high level power transformation low level; V6 becomes cut-off state by conducting, ac contactor coil KM dead electricity, and main contact discharges; disconnect the three phase mains of motor, motor is played rapid and reliable protection.

Form analog current by R7, V5, RP1 and power supply E2+ and adjust circuit; can produce a stable analog current; the operating state of simulating motor; after the A/D conversion; show its numerical value in mode intuitively; analog current compares the operating state of back by executive circuit control protector with the setting value that presets, and reaches the purpose of the operating state of adjusting protector exactly by the setting of analog current.

Claims (3)

1; a kind of passive motor protector; comprise the three-phase current detection coil; comparator circuit; amplification driving circuit and final controlling element; the output of three-phase current detection coil is connected with the comparator circuit input; comparator circuit output is amplified output through amplification driving circuit and is controlled the A.C. contactor that is used with motor protector; the main contact of A.C. contactor is connected in the motor three phase mains inlet wire and controls motor power; it is characterized in that: described comparator circuit (1) power supply is by three-phase current detection coil (L1); (L2); (L3) going up induced electromotive force provides behind rectification circuit (4) rectifying and wave-filtering, and amplification driving circuit is made of contactless electronic AC switch circuit (2).

2, passive motor protector according to claim 1, it is characterized in that: described rectification circuit (4) is made of diode (V1), (V2), (V3) and filter capacitor (C1), the positive pole of diode (V1), (V2), (V3) is connected with the end of electric current detecting coil (L1), (L2) and (L3) respectively, negative pole is connected to each other and constitutes positive source together, electric current detecting coil (L1), (L2) and the other end (L3) are connected to each other and constitute power cathode together, and filter capacitor (C1) is connected between the power supply positive and negative electrode; Described contactless electronic AC switch circuit (2) is by resistance (R1); (R2); (R3) triode (V4); (V5) and controllable silicon (V6) and bridge rectifier (3) constitute; bridge rectifier (3) dc output end just; be connected to controllable silicon (V6) between the negative pole; triode (V4) collector electrode is received dc power anode by resistance (R1); triode (V5) base stage is connected with triode (V4) collector electrode; triode (V5) collector electrode one tunnel also is connected to dc power anode through resistance (R3); another road is connected with controllable silicon (V6) trigger electrode; triode (V4) and emitter (V5) are received dc power cathode simultaneously; triode (V4) base stage is connected with comparator circuit (1) output, and bridge rectifier (3) ac input circuit is exported as passive motor protector.

3, according to claim 2, it is characterized in that: going back cross-over connection in the described contactless electronic AC switch circuit (2) between the base stage of triode (V4) and the collector electrode (V5) has resistance (R2), is connected to anti-interference capacitor (C2) between triode (V5) base stage and the direct current negative pole.