CN2279728Y - Open-phase overloading protector for three-phase motor - Google Patents

Abstract

The utility model relates to an open-phase and overloading protector for a three-phase motor, which comprises a full-wave rectification circuit, an overloading circuit and a phase interruption circuit. The utility model is characterized in that the utility model also comprises an automatic maintenance holding circuit which is composed of diodes and capacitors, and the both ends of the coil of a relay J are added with a DC voltage. The utility model can not only be used in equipment which is provided with a manual switch but also can be used for equipment which is provided with an automatic switch, the utility model overcomes the defect that the existing open-phase and overloading protectors for the three-phase motor is suitable for only equipment which is provided with the manual switch, and therefore, the utility model is suitable for the phase interruption protection and overloading protection of three-phase motors.

Description

Threephase motor overload of loss of phase protective device

The utility model relates to a kind of threephase motor overload of loss of phase protective device.

" three phase electric machine overload of loss of phase protective device " its patent No. of using on the existing market is 87205604; though in the protection of motor, played positive use; but it can only be useful on the equipment of hand switch; and can not be used on the equipment of automatic switch; limit the scope of application, because the too small protector of empty load of motor electric current also can move, be prone to misoperation in use; the control line connection is different with thermal relay, and the user feels trouble.

The purpose of this utility model is to provide a kind of and both can have used on the equipment of hand switch; can use again on the equipment of automatic switch; can not move at the too small protector of electric current, thereby avoid misoperation, and can make user's a kind of threephase motor overload of loss of phase protective device easy to use.

Basic scheme of the present utility model is by full-wave rectification circuit, overload circuit, phase failure circuit and keeps circuit four parts automatically and constitute, full-wave rectifying circuit is made up of instrument transformer, diode and electric capacity, the overload circuit is made up of potentiometer, resistance, electric capacity, triode and relay, phase failure circuit by instrument transformer, diode, triode, and peripheral cell constitute, keep circuit automatically and form by diode and electric capacity.To be full-wave rectifying circuit go out alternating voltage and obtain a direct voltage by transformer induced its operation principle, when motor runs well, triode in the overload circuit is in cut-off state, when motor overload, direct voltage raises, the voltage that is added on the triode also increases and then conducting thereupon, the actuating of relay and reach the purpose of protection; Phase failure signal in the phase failure circuit is obtained by instrument transformer, and on rectification, filtering were added in triode in the phase failure circuit, during this triode conducting, the collector electrode no-voltage existed, if the phase failure takes place then this triode ends, thus the control relay action.When the utility model used on automatic equipment, in case the phase failure or overload take place, then the contact of relay opened; make that holding circuit equals to add a direct voltage to the relay two ends; minimum because of its power consumption, will not make A.C. contactor adhesive again, reached the purpose of protection motor.

Advantage of the present utility model is that it not only can use on the equipment of hand switch, and can also use on the equipment of automatic switch, thereby has enlarged the scope of using.Because protector can not move yet when electric current is too small, so can avoid misoperation.Because of the connection of the connection of control line and thermal relay identical, so that the user uses is just very convenient.

Below in conjunction with drawings and Examples the utility model is further specified.

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

Among Fig. 1, M is a motor, the full-wave rectification circuit is made up of instrument transformer L1, L2, L3, diode D1-D8 and capacitor C 1, described overload circuit is made up of potentiometer W1, W2, resistance R 1, R2, R3, R4, capacitor C 3, triode BG1, BG2, relay J and capacitor C 5, described phase failure circuit is made up of instrument transformer L4, L5, L6, diode D9, capacitor C 4, triode BG3, resistance R 5, diode D12, and the described circuit of keeping automatically is made up of diode D10, D11 and capacitor C 2.Circuit working principle of the present utility model is that the secondary induction by 3 instrument transformer L1, L2 and L3 goes out alternating voltage, and the full-wave rectifying circuit through diode D1-D8 and capacitor C 1 are formed can obtain a direct voltage at the two ends of C1.Its overload operation principle is W1 and the W2 positive definite cut-off state at triode BG1 when motor normally moves; electric current can rise when motor overload; direct voltage also can raise; the voltage that is added in triode BG1 base stage also can increase makes its conducting; BG2 also can conducting, and relay J reaches the protection purpose because of electric current is arranged by moving.Phase failure signal is to obtain from the secondary coil of another group instrument transformer L4, L5 and L6, be added on the base stage of triode BG3 through rectification and direct voltage of filtering acquisition, can make triode BG3 conducting, the collector electrode no-voltage exists, if the voltage of phase failure triode BG3 base stage takes place can disappear, triode BG3 can end, collector electrode just has voltage by the base stage diffluence of diode D12 to triode BG1, equal to add an overload signal and given the base stage of triode BG1, make the rapid conducting of triode BG1, BG2, relay J just has electric current by making its action.When on the equipment of automatic switch, using; in case the relay J action was opened contact when the phase failure or overload took place; have the alternating voltage of a 220V or 380V between 2 of the contact of J; make capacitor C 5, diode D11, D10 add a direct voltage for the two ends of relay J coil; because of its power consumption minimum; have only 2% watt, will not make A.C. contactor adhesive again, so just protected motor.When if the phase failure occurs in the upper end of the arbitrary phase that is connected on the ac contactor coil two-phase, though 2 no-voltages of relay J action back contact can make the contact of relay J closed again, because of no-voltage A.C. contactor also not adhesive again.

Claims (1)

1. a threephase motor overload of loss of phase protective device comprises full-wave rectifying circuit, overload circuit, phase failure circuit, it is characterized in that it also comprises to keep circuit automatically, sensor L in the full-wave rectifying circuit ₁, L ₂, L ₃And diode D ₁～D ₈And capacitor C ₁Obtain alternating voltage after rectification obtains a direct voltage, this circuit is connected with the overload line circuit, and control is by potentiometer W ₁, W ₂, resistance R ₁～R ₄, capacitor C ₃, triode BG1, BG2 and peripheral cell are formed overload circuit, and phase failure circuit is by instrument transformer L ₄, L ₅, L ₆, diode D ₉, D ₁₂Triode BG3 and peripheral cell constitute, L ₄, L ₅, L ₆Induction phase failure signal also adds to through rectification on the base stage of BG3, and relay J one end is connected with the base stage of triode BG3, and the other end passes through R ₅Be connected with the base stage of BG1, automatic maintaining circuit is by diode D ₁₀, D ₁₁And capacitor C ₂Constitute, give on the relay J coil to add a direct voltage.