CN2241407Y - Under-voltage open-phase protector for motor - Google Patents

Abstract

The utility model discloses an under-voltage open-phase protector for a three-phase asynchronous motor, comprising a voltage detection part, a current detection part, an actuating mechanism, and a power supply. The under-voltage open-phase protector for a three-phase asynchronous motor adopts a voltage division principle to divide the voltage of three phase electricity via three sets of series resistors and connect the three sets of series resistors into a Y shape. The under-voltage open-phase protector for a three-phase asynchronous motor adopts a current induction principle to design three reed switches for detecting disconnection. A minitype power transformer is rectified and filtered waves, which enables the electricity of 12V to switch on five transistors and four relays. Seven contact switches are respectively arranged on the three reed switches and the four relays, and six of the contact switches are mutually connected in series to form a control switch DE. When any phase electricity excesses voltage or lose phase, one corresponding contact switch can be broken off, then the control switch DE is broken off, and an actuating control switch HL is also broken off. Thus, a motor control hoop is cut off, and the utility model obtains the goal of motor protection.

Description

Motor undervoltage open-phase protection device

The utility model relates to a kind of electric motor protecting technology, particularly can in time control the device of being protected by the control loop of controlled motor to threephase asynchronous when under-voltage, the phase failure.

General three-phase asynchronous motor protector is to utilize electromagnetic induction principle; by being detected the whether phase failure having or not of electric current; this protector is worked as threephase asynchronous and is normally moved; during the arbitrary phase failure suddenly mutually of power transformer primary side high pressure; also in operation, three-phase current still exists motor, at this moment depends merely on electromagnetic induction principle and judges that the phase failure will produce the serious consequence of burning motor; it is to open circuit, and can not protect motor under the situation of " phase failure ".

The purpose of this utility model is for remedying the deficiencies in the prior art; providing a kind of under-voltage, the phase failure under any circumstance takes place all can accurately cut off the electricity supply; motor is under-voltage, phase failure protector, and it can avoid taking place because of the accident under-voltage, that motor is burnt in the phase failure effectively.

The purpose of this utility model is to realize like this; this protector is by voltage detecting and controling circuit; current detection control circuit; carry out control circuit; four parts such as small power transformer constitute; voltage detecting and controling circuit is that three-phase electricity is connected into the Y type through three groups of series connection divider resistances; last resistance two ends in every mutually every group resistance wherein are connected with three whole devices respectively, the anode of three rectifiers again respectively with three capacitors; three resistance connect; three triodes respectively with three pulling relay coils; six resistance connect; three pulling relay coils are connected with power supply again; three pulling relay coils are provided with normally opened contact switch DF.

Current detection control circuit is to be provided with normally opened contact switch GE to connect with voltage detecting and controling circuit switch DF on three tongue tubes that are wound with lead respectively, be connected in series mutually respectively with by the power line of controlled motor D around lead.

Carrying out control circuit is with triode BG ₁, BG ₂Be connected with an end, power supply, resistance, electric capacity, the tandem tap DE of pulling relay coil respectively, pulling relay coil is provided with control switch HL and is connected with the control loop of Be Controlled motor.

Small power transformer B is connected with the rectifier two ends, and the rectifier anode is connected with filter capacitor, a triode, four pulling relay coils.

Because the utility model adopts voltage divider principle; with three-phase electricity through three groups of series resistance dividing potential drops; can when the phase failure of high pressure primary side, protect motor; so the protective value of this protector is flexible, accurate, errorless; because the utility model adopts the electric current magnetic induction principle to design three tongue tube detection circuits simultaneously; so no matter it is under-voltage to motor, or the phase failure or open circuit and all can in time protect.In addition, the utility model is simple in structure, and the used unit cost is low, so it is the optimum motor protector of very easily promoting the use of.

Below in conjunction with drawings and Examples concrete structure of the present utility model and operation principle are described in further detail.

Fig. 1 is voltage detecting and controling circuit figure;

Fig. 2 is a control switch DF schematic diagram among Fig. 1;

Fig. 3 is current detection control circuit figure;

Fig. 4 is that Fig. 3 is towards control switch GE schematic diagram;

Fig. 5 is the miniature transformer circuit diagram;

Fig. 6 carries out control circuit figure;

Fig. 7 is that motor is under-voltage, phase failure protector integrated circuit winding diagram.

This protector is to be made of four parts such as voltage detecting and controling circuit, current detection control circuit, execution control circuit, small power transformers, and voltage detecting and controling circuit is through divider resistance R with three-phase electricity A, B, C _A1R _A20, R _B1R _B20, R _C1R _C20Be connected into the Y type, R _A20, R _B20, R _C20Each two ends is connected with rectifier QLA, QLB, QLC respectively, the anode of rectifier QLA, QLB, QLC respectively with three capacitor C _A, C _B, C _C, three resistance R ₃, R ₅, R ₇One end connects, three triode BG _A, BG _B, BG _CCollector electrode respectively with three 12V direct current relay pull-in winding DC _A, DC _B, DC _CConnect, emitter is ground connection (O) respectively, base stage respectively with resistance R ₃, R ₄, R ₅, R ₆, R ₇, R ₈One end connects, three 12V direct current relay pull-in winding DC _A, DC _B, DC _CBe connected the normally opened contact K of these three pulling relay coils again with power supply 12V positive source _A, K _B, K _CBe serially connected in switch DF mutually.

Current detection control circuit be with around three tongue tubes respectively around several circles or tens circle leads, determine according to the watt level of Be Controlled motor D around the diameter of wire and the number of turn, be respectively equipped with the normally opened contact K switch on three tongue tubes ₁, K ₂, K ₃Be serially connected in switch GE mutually, institute's coiling is connected in series respectively with by the power line of controlled motor D mutually on three tongue tubes.

The power supply transformation B of protector is formed by " day " font silicon steel plate packing, and the logical 380V voltage second siding ring of first siding ring induces the 12V alternating current, transformation B second siding ring two ends respectively with rectifier QL ₁Two ends connect, QL ₁Negative terminal is ground, QL ₁Anode and filter capacitor C ₁Anode be connected capacitor C ₁Negativing ending grounding, rectifier QL simultaneously ₁Anode again respectively with triode BG ₂Emitter, pulling relay coil DC ₁One end, pulling relay coil DC _A, DC _B, DC _CAn end be connected.

The actuating mechanism controls circuit is with triode BG ₁Collector electrode and pulling relay coil DC ₁The other end be connected, emitter and power supply () negative pole is connected, base stage respectively with resistance R ₂One end, capacitor C ₂Anode be connected triode BG ₂Collector electrode respectively with resistance R ₂The end of the other end, tandem tap DE is connected, base stage and resistance R ₁One end is connected, R ₁The other end is connected pulling relay coil DC with the end in addition of tandem tap DE again ₁On normally opened contact K ₅For switch HL is connected with the control loop of Be Controlled motor.When motor power voltage just often, three-phase electricity A, B, C are through dividing potential drop precision resistance R _A1R _A20, R _B1R _B20, R _C1R _C20At R _A20, R _B20, R _C20The two ends pressure is again through rectifier QLA, QLB, QLC full-wave rectification, through capacitor C _A, C _B, C _CFiltering is again through biasing resistor R ₃R ₄, R ₅R ₆, R ₇R ₈Offer triode BG respectively _A, BG _B, BG _CBase potential (0.7V), make triode BG _A, BG _B, BG _CConducting, three 12V direct current midget relay coil DC _A, DC _B, DC _CGet electrical contact switch K _A, K _B, K _CClosure, i.e. DF closure.If three-phase electricity A, B, C wherein A are disconnected mutually, R _A20The two ends alternating voltage reduces, triode BG _ABase potential less than 0.2V, promptly end 12V direct current relay pull-in winding DC _ADead electricity discharges, contact switch K _ADisconnect, switch DF promptly disconnects so.When line voltage is lower than 360V or sets the control voltage range according to user's needs, triode BG _A, BG _B, BG _CBase potential is promptly ended less than 0.3V, three 12V direct current relay pull-in winding DC _A, DC _B, DC _CDead electricity discharges, contact switch K _A, K _B, K _CDisconnect, promptly DF disconnects.

According to electromagnetic principle, when motor normally moved, three-phase electricity A, B, C all had electric current to pass through the outer coiling of three tongue tubes, produce alternating magnetic field, contact switch K around the coil ₁, K ₂, K ₃Exchange closedly under magneticaction, i.e. GE closure is if the contact switch K of tongue tube is promptly opened circuit in arbitrary phase B phase failure ₂Do not have magneticaction promptly to disconnect, promptly GE disconnects.

When three-phase electricity A, B, c-power supply voltage normal, when motor does not have the phase failure, voltage detection switch K _A, K _B, K _CClosure, i.e. switch DF closure, current detection switch K ₁, K ₂, K ₃Closure, i.e. switch GE closure, control switch DE closure, at this moment the execution work circuit under the DE effect, triode BG ₂, BG ₁Conducting, pulling relay coil DC ₁Must be electric, contact switch K ₅Closure, i.e. control switch HL closure.Otherwise motor is arbitrary, and the phase failure takes place mutually, when supply voltage reduces, and contact switch K _A, K _B, K _C, K ₁, K ₂, K ₃Any disconnects inductive switch, and promptly control switch DE disconnects, at this moment triode BG ₁, BG ₂End pulling relay coil DC ₁Dead electricity discharges, contact switch K ₅Disconnect, promptly control switch HL disconnects, and cuts off the control loop of motor, promptly cuts off the major loop of motor, and then reaches the purpose of protection motor.

The utility model is suitable for the motor of dried magnetic starter or A.C. contactor control, and wound-rotor motor also is suitable for.

Claims (3)

1, motor is under-voltage, phase failure protector, be by voltage detecting and controling circuit, current detection control circuit, carry out control circuit, four parts such as small power transformer constitute, it is characterized in that: voltage detecting and controling circuit is that three-phase electricity is connected into the Y type through three groups of series connection divider resistances, last resistance two ends in wherein every mutually every group resistance are connected with three rectifiers respectively, the anode of three rectifiers again respectively with three capacitors, three resistance connect, three triodes respectively with three pulling relay coils, six resistance connect, three pulling relay coils are connected with power supply again, and three pulling relay coils are provided with normally opened contact DF;

Current detection control circuit is to be provided with normally opened contact switch GE to connect with voltage detecting and controling circuit switch DF on three tongue tubes that are wound with lead respectively, be connected in series mutually respectively with by the power line of controlled motor D around lead;

Carrying out control circuit is that triode is connected with an end, power supply, resistance, electric capacity, the tandem tap DE of pulling relay coil respectively, and pulling relay coil is provided with control switch HL and is connected with the control loop of Be Controlled motor D;

Small power transformer B is connected with the rectifier two ends, and the rectifier anode is connected with the pull-in winding of filter capacitor, a triode, four relays.

2, under-voltage, the phase failure protector of motor according to claim 1, its feature also is: the contact switch DF on three pulling relay coils is by three contact switch K _A, K _B, K _CBe composed in series mutually, the normally opened contact switch GE on three tongue tubes is by three contact switch K ₁, K ₂, K ₃Be composed in series mutually, tandem tap DE is by six contact switch K _A, K _B, K _C, K ₁, K ₂, K ₃Be composed in series mutually.

3, under-voltage, the phase failure protector of motor according to claim 1 and 2; it is characterized in that: on the tongue tube around the number of turn of lead and diameter according to being determined that by the watt level of controlled motor D small power transformer is formed by " day " font silicon steel plate packing.

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