CN2036325U

CN2036325U - Protection switch for electric motor lacking phase

Info

Publication number: CN2036325U
Application number: CN 88210376
Authority: CN
Inventors: 丁柏仁
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-05
Filing date: 1988-04-05
Publication date: 1989-04-19

Abstract

The utility model relates to an electric protective device. A protection device for lacking phase of an electric motor is required to prevent the motor from being burnt out due to lacking phase while the motor is in action. The utility model provides a protection switch for lacking phase of an electric motor with new structures, and improves a relay, so that the protection switch has the double functions of a relay and a switch for starting or stopping. The protection device has simplified structure and reduced cost.

Description

Protection switch for electric motor lacking phase

The utility model relates to a kind of improved electric protective device.

Phase-deficient operation can cause burn-down of electric motor if threephase asynchronous machine is in operation, so generally all by electric motor protective device is housed.The principle of the electric motor protective device that adopts both at home and abroad all is with the protection motor by voltage signal, current signal or thermal relay control executing mechanism open circuit at present; the phase-lacking protective device of existing all kinds of motors (except that the minority low-power machine) substantially all is made up of A.C. contactor, relay and starting switch; there is complex structure, the characteristics that cost is high.

The utility model proposes a kind of motor open-phase protection switch of new structure,, reach and simplify the open-phase protection switch, reduce the purpose of its cost by change to individual elements.

This motor open-phase protection switch operation principle as shown in Figure 3, L ₁, L ₂, L ₃Be three quick-magnetic saturated current transformers, the elementary access respectively in A, B, the C three-phase, secondary head and the tail link and are connected into open-delta, and when the three-phase symmetrical operation, because secondary fundamental voltage three-phase equal and opposite in direction, and every phase phase difference is 120 °, so U ' _A1+ U ' _B1+ U ' _C1=0, and three-phase third harmonic voltage equal and opposite in direction, but phase place is identical, so open-delta opening voltage ∑ U '=U ' _A3+ U ' _B3+ U ' _C3=3U ' _A3, through D ₁Rectification and C filtering make the J action.During any phase phase shortage, all the other two-phase current phase places are opposite, and resultant current is zero J to be discharged, A.C. contactor, and the QC dead electricity disconnects major loop.Its course of work such as Fig. 1, Fig. 2, shown in Figure 3, when when starting, pressing armature of relay 1(with hand is QA among Fig. 3, and a latex cover is arranged on the armature, plays the waterproof and dustproof effect, hand does not directly contact with armature 1 again.) at this moment little feeler lever bar 3 promotes contacts 4 and contacts with contact 5 on the armature; A.C. contactor QC gets electric adhesive starting, in the time of starting, triple harmonic current from triangle open mouth through D ₁Rectification, it is electric that relay coil 2 is got, and holds armature 1, makes

contact

4 and 5 keep in touch state.When needing to shut down; as long as press the bending sheet metal 6 on the motor type relay downwards, because leverage, the feeler lever 7 on the sheet metal 6 travels forward; compress the facade of armature 1; it is return, and feeler lever 3 leaves contact 4, and contact 4 disconnects with contact 5 under elastic reaction; A.C. contactor QC dead electricity is stopped motor; J is discharged, and contact 4 and 5 disconnects automatic stopping.

The protection switch for electric motor lacking phase that the utility model proposes is combined as a whole relay and starting switch, and relay plays the effect of button simultaneously, stops button thereby remove one pair of startup, has simplified the phase shortage protective device, has reduced cost.

Fig. 1, Fig. 2 are front view and the vertical views of an embodiment of relay startup and shut-down mechanism, 1 is the armature of relay among the figure, the 2nd, relay coil, the 3rd, the feeler lever of armature, 4, the 5th, two groups of contacts of relay, the 6th, the sheet metal of bending, the 7th, the feeler lever on the sheet metal, the 8th, lay the framework that bends sheet metal.

Fig. 3 is an embodiment of electric wiring of the present utility model, and A, B, C are three phase mains among the figure, D _A, D _B, D _CBe the wiring point of motor, QC is an A.C. contactor, and J is a relay, and QA represents the starting button (being armature) of relay, and TA represents the stop button of relay.D ₁, D ₂Be diode, L ₁, L ₂, L ₃For being used for the quick-magnetic saturated current transformer of wireline inspection.R is the resistor in the circuit, and C is a capacitor.

Claims

1, a kind of motor open-phase protection switch of forming by relay, A.C. contactor; it is characterized in that said relay is being equipped with the sheet metal of a bending with the corresponding position of the armature on it; sheet metal is contained on the framework, and a feeler lever is housed on the sheet metal.