CN2177296Y

CN2177296Y - Motor protector

Info

Publication number: CN2177296Y
Application number: CN 93245938
Authority: CN
Inventors: 吴贤君
Original assignee: FENGHUA CITY POWER SAVING ELECTRIC FACTORY
Current assignee: FENGHUA CITY POWER SAVING ELECTRIC FACTORY
Priority date: 1993-11-27
Filing date: 1993-11-27
Publication date: 1994-09-14
Anticipated expiration: 2003-11-27

Abstract

The utility model relates to a motor protective device. The utility model relates to an emergency protective circuit device of the motor. The utility model is the improvement for the prior art. Three current mutual inductors are adopted to connect in series and in sequence. Signals are respectively checked by the manner of coupling A, B and C three phases, wherein, three potentiometers are adopted to regulate the range and the concrete value of the overload current in a current setting circuit simultaneously. The utility model can perform accurate and timely judgment for the faults of the overcurrent, the open phase, etc., of the A, B and C three phases. The utility model can also postulate the range of the overload current and the concrete value of the overload current, in order to adapt the motors with different capacitance.

Description

Motor protector

A kind of motor protector relates to the emergency protective circuit device of motor, is improvements over the prior art.

Chinese patent CN2088753U discloses a kind of motor protector, adopts current detection technology, not with the design of supply transformer.The electromagnetic actuator that replaces having the contact by SCR AC switch.Also include the rectifying and wave-filtering link, current settings link, integration time delay process, electronic DC switch and current limiting pressure-limiting circuit.Though this protector has characteristic of simple structure because its input link has only a coupling coil, and only with three-phase electricity in arbitrary being coupled.Therefore pair phase shortage, the untimely shortcoming of overload phenomenon reaction are arranged.

The purpose of this utility model just is the shortcoming at prior art, designs a kind of three coupling coils that have, and can adjust the motor protector of overload current according to the difference of load.

The utility model includes signal deteching circuit, current rectifying and wave filtering circuit, current setting circuit, one-way SCR, reaches A.C. contactor, the signal that is obtained by signal deteching circuit is sent to current setting circuit behind current rectifying and wave filtering circuit, break-make from the signal controlling one-way SCR of current setting circuit output, the break-make of one-way SCR is then controlled whether conducting of A.C. contactor, it is characterized in that described signal deteching circuit is by three current transformer CT ₁, CT ₂, CT ₃Series connection is along connecing formation, and be coupled respectively A, B, C three-phase.

Therefore the utility model can in time detect the phase failure, the overcurrent of arbitrary phase owing to adopt three current transformer series connection along connecing.Simultaneously owing to adopt potentiometer to regulate, can adapt to different capabilities motor, and can in different overload current scopes, specifically set the numerical value of overload current.And the utility model also has advantage simple in structure, that cost is low, versatility is good.

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

Fig. 1 is the utility model circuit theory diagrams.

Fig. 2 is the connection diagram between the utility model and motor and the contactor.

As shown in Figure 1, signal deteching circuit is by the suitable current transformer CT that connects of three series connection ₁, CT ₂, CT ₃Form.And these three instrument transformers are that the coil by the identical number of turn of coiling on three identical soft magnetism rings makes.Three of three-phase electricity power line A, B, C pass three instrument transformers respectively during use.The signal that obtains from current transformer is through rectifier bridge rectification, capacitor C ₁Transfer to the current setting circuit current setting circuit after the filtering by potentiometer W ₁, W ₂, W ₃, resistance R ₁, R ₂, capacitor C ₂, triode T ₁, T ₂Form.Potentiometer W ₁Be connected to C ₁Two ends, and that end that links to each other with its sliding contact is through R ₁After be connected to triode T ₁Base stage.Potentiometer W ₂One is terminated at C ₁Positive pole and W ₁Tie point on, the other end is connected to R ₂With R ₁Tie point on.R ₂The other end be connected to T ₁Collector electrode, R ₃The other end be connected to T ₂Collector electrode.Potentiometer W ₃One end and rectifier bridge negative pole join, the other end and T ₁Emitter joins.Capacitor C ₂Positive pole is connected to T ₁On the base stage, negative pole is connected to T ₁Emitter.Electronic switching circuit is made up of one-way SCR K.The one-way SCR control utmost point and T ₂Emitter join.R ₄The control utmost point of one termination one-way SCR K, another termination T ₁Emitter.The two ends of one-way SCR K again and connect one by D ₁, D ₂, D ₃, D ₄The full-wave rectifying circuit of forming.

And for example shown in Figure 2, three power line A, B of three-phase electricity, C pass three current transformers on the protector (1) respectively.A phase line of the termination three-phase electricity of A.C. contactor C, the other end is through being connected on behind push-button switch TA, the QA on another root phase line.The pair of control line of drawing from protector is connected on the two ends of QA respectively.Three contacts of contactor C are serially connected in respectively in the power line, and another contact is serially connected on the control line of drawing from protector.

Pass through W ₁, W ₂, W ₃After overload current scope and occurrence setting, by CT ₁, CT ₂, CT ₃The signal of induction transfers to current setting circuit behind rectifying and wave-filtering.When A, B, C three-phase just often, T ₁Base voltage is extremely low, T ₁End, signal is through W ₂, R ₂Transfer to T ₂Thereby, trigger the K conducting, make C work.When in A, B, the C three-phase when arbitrary phase phase failure or phase shortage, K closes, and C quits work.As if A, B, when overcurrent appears in the C three-phase, T ₁Base voltage increases, T ₁Conducting, T ₂End, K closes, and C quits work.

Claims

1, a kind of motor protector; include signal deteching circuit, current rectifying and wave filtering circuit, current setting circuit, one-way SCR, reach A.C. contactor; the signal that is obtained by signal deteching circuit is sent to current setting circuit behind current rectifying and wave filtering circuit; break-make from the signal controlling one-way SCR of current setting circuit output; the break-make of one-way SCR is then controlled whether conducting of A.C. contactor, it is characterized in that described signal deteching circuit is by three current transformer CT ₁, CT ₂, CT ₃Series connection is along connecing formation, and be coupled respectively A, B, C three-phase.

2, motor protector according to claim 1 is characterized in that current setting circuit is by potentiometer W ₁, W ₂, W ₃, resistance R ₁, R ₂, capacitor C ₂And triode T ₁, T ₂Form W ₂, W ₃An end be connected to W respectively ₁Two ends, W ₁That end that links to each other with sliding contact is through R ₁After be connected to T ₁Base stage, W ₂The other end is connected on R ₂, R ₃Tie point on, R ₂Another termination T ₁Collector electrode, R ₃Another termination T ₂Collector electrode, W ₃Another termination T ₁Emitter, C ₂Positive pole meets T ₁Base stage, negative pole meet T ₁Emitter, T ₂Base stage meets T ₁Collector electrode, T ₂Emitter is through R ₄After meet T ₁Emitter.