CN2151566Y - Open-phase protector for three-phase ac motor - Google Patents

Abstract

The utility model relates to a phase interruption protector for three-phase AC motor, which is composed of a magnetic ring coils component and an AC contactor, and a bidirectional thyristor component which is connected in series with a self locking contact head is arranged between the magnetic ring coils component and a control circuit. The utility model has the advantages of convenient operation, low cost and few elements, and the problem of working reliability of like products is solved.

Description

Open-phase protector for three-phase ac motor

The utility model relates to a kind of phase failure protector of three-phase alternating-current motor.

In the prior art, the phase failure protector of three-phase alternating-current motor generally is divided into: thermal relay class, residual voltage relay class, under voltage protection device (comprising voltage relay), fuse class, undercurrent protection device (comprising current relay) and various types of transistor protection devices or the like, in these protectors, thermal relay moves when underloading or phase shortage hardly; The residual voltage relay wiring is simple, but residual voltage and phase shortage are not linear, and residual voltage regulate to be difficult to is grasped, and tends to take place misoperation or this easily; If the phase failure of under voltage protection device is created in the below of main noddle on contactor, voltage relay contact, can't realize protection; The fuse burn out relay protection can only be protected fuse failure, and limitation is very big; The undercurrent protection device can be realized protection reliably to motor, but needs three current relays to be serially connected on the main circuit of big electric current, uses very inconvenience; The transistor protection device is relatively sensitiveer, but most of structure more complicated, thereby cause himself poor anti jamming capability.

In order to overcome above-mentioned weak point, the purpose of this utility model is to provide the phase failure protector of a kind of simple in structure, reliable operation, easy to use, cheap three-phase alternating-current motor.

The utility model comprises magnetic ring coil assembly and A.C. contactor, it is characterized in that being provided with the bidirectional triode thyristor assembly that is in series with the self-locking contact between the self-locking branch road of magnetic ring coil circuit and control circuit.

Above-mentioned three-phase alternating-current motor phase failure protector is characterized in that the bidirectional triode thyristor assembly can be that three bidirectional triode thyristors are in series.

Above-mentioned three-phase alternating-current motor phase failure protector is characterized in that the main electrode of bidirectional triode thyristor is connected on the self-locking branch road, and the control utmost point is connected in the magnetic ring coil circuit.

The utility model utilizes electromagnetic induction principle, and magnetic ring coil is placed the triple line of main circuit, obtains induced electromotive force, the conducting control utmost point; When pressing the starting button QA of control circuit, main electrode a, the b of bidirectional triode thyristor are coupled with voltage, thereby make the bidirectional triode thyristor conducting, and a, b constitute path, electric motor normal working; When the main circuit phase shortage; magnetic ring coil corresponding to the phase shortage circuit does not produce induced electromotive force; make its corresponding bidirectional triode thyristor control polar circuit be in cut-off state; the main electrode circuit of this bidirectional triode thyristor also is in cut-off state; thereby, the self-locking branch circuit break of control circuit, contactor coil C does not have electric current to pass through; motor main circuit is forced to outage, has reached the purpose of open phase protection thus.

Below in conjunction with accompanying drawing the utility model embodiment is done to describe in detail:

Fig. 1 is the circuit theory diagrams of the utility model embodiment.

With reference to Fig. 1, the utility model comprises magnetic ring coil (M1, M2, M3) assembly and A.C. contactor C, it is characterized in that being provided with bidirectional triode thyristor (T1, T2, T3) assembly that is in series with self-locking contact C between the self-locking branch road of magnetic ring coil circuit and control circuit, bidirectional triode thyristor (T1, T2, T3) assembly is three bidirectional triode thyristors (T1, T2, T3) series connection of assembly, bidirectional triode thyristor (T1, T2, T3) main electrode (a of assembly, b) be connected on the self-locking branch road of electromotor control circuit, (d1, d2 d3) are connected on magnetic ring coil (M1 respectively to the control utmost point, M2 is in circuit M3).When pressing starting button QA, (T3) (a b) is coupled with voltage to the main electrode of assembly to bidirectional triode thyristor, thereby makes the bidirectional triode thyristor conducting, the conducting of self-locking branch road for T1, T2; When the main circuit three-phase line was all worked, (M1, M2 M3) obtained induced electromotive force to magnetic ring coil, and (d1, d2 d3), thereby make bidirectional triode thyristor (T1, T2, T3) assembly conducting, (a, b) formation path, electric motor normal working to the conducting control utmost point; When the main circuit phase shortage; magnetic ring coil corresponding to the phase shortage circuit (for example: during the short of electricity of A phase does not produce induced electromotive force; magnetic ring coil M3 does not produce induced electromotive force); make its corresponding bidirectional triode thyristor control utmost point (for example d3) be in cut-off state; thereby make the main electrode of bidirectional triode thyristor (for example T3) be in cut-off state; therefore; self-locking branch road (a; b) open circuit; the contactor coil C of the control circuit of motor D does not have electric current to pass through; the main circuit of motor D is forced to outage, has reached the purpose of open phase protection thus.

By above analysis as can be seen, the utlity model has simple, current relay reliable of residual voltage relay, the sensitivity of transistor relay, and reject the intrinsic shortcoming of these elements self, therefore, simple in structure, the reliable operation, easy to use, cheap of the utility model.

Claims (3)

1, a kind of three-phase alternating-current motor phase failure protector comprises magnetic ring coil assembly and A.C. contactor, it is characterized in that being provided with between the self-locking branch road of magnetic ring coil circuit and control circuit the bidirectional triode thyristor assembly that is in series with the self-locking contact.

2, three-phase alternating-current motor phase failure protector as claimed in claim 1 is characterized in that the bidirectional triode thyristor assembly can be that three bidirectional triode thyristors are in series.

3, three-phase alternating-current motor phase failure protector as claimed in claim 1 or 2 is characterized in that the main electrode of bidirectional triode thyristor assembly is connected on the self-locking branch road, and the control utmost point is connected in the magnetic ring coil circuit.

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