CN2164605Y

CN2164605Y - Phase-loose protector

Info

Publication number: CN2164605Y
Application number: CN 93234387
Authority: CN
Inventors: 王仲初; 王合江
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-07-24
Filing date: 1993-07-24
Publication date: 1994-05-11
Anticipated expiration: 2003-07-24

Abstract

The utility model relates to a phase-loose protector, comprising a rectification, wave filtering, and voltage stabilization circuit, a comparison and amplification circuit, and a control circuit. The phase-loose protector adopts voltage to sample points which is calculated and amplified by an IC. The utility model has the advantages of small size, light weight, convenient installation, simple wiring, reliable work, high sensitivity, wide application range, etc. The utility model is suitable for the phase-loose protection of the AC low-voltage electrical apparatus of the three phase four wire system of the voltage of 380V.

Description

Phase-loose protector

The utility model relates to a kind of open phase protection of three-phase four-wire low-voltage ac electric apparatus.

At present; the low-tension motor open-phase running causes the accident that burns out often to take place, when considering the safeguard measure of low voltage motor, and general only consideration installing fast acting fuse and thermal relay protection; this scheme can not fully not protected the single phasing of motor, so that the generation that causes the accident.Existing protection against single phasing measure is but because there is price more expensive; the wiring trouble perhaps is installed; or can not play the shortcomings such as effect of open phase protection fully; so it is not extensive in actual applications; as Chinese patent communique disclosed " application number 88203069 phase failure protector of electric motor "; though it is simple in structure, cost is low; but it is confined to when fuse blows; could protect motor; if other reason is when causing the phase failure; just can not protect motor, it is the effect that can not play open phase protection fully.For the open phase protection of other three-phase four-wire low-voltage ac electric apparatus, also continue to use technique scheme basically, so also there is the many and protection defect of insufficient of misoperation.

The purpose of this utility model is to provide the phase failure protector of the three-phase four-wire low-voltage ac electric apparatus of a kind of wide accommodation, reliable operation.

Task of the present utility model is finished with following mode: it comprises rectification, filtering, voltage stabilizing circuit, comparison amplifying circuit and control circuit.Capacitor C 1, C2, C3 electricity by Y-connection connect three phase mains, be connected in series the rectifier Z in the rectification filtering voltage stabilizing circuit between its neutral point N ' and the zero-power line N, on the rectification filtering voltage stabilizing circuit dc output end and connect the resistance bridge of forming by resistance R 1, R2, R3, potentiometer W, two dividing potential drop output electricity of this resistance bridge connect two inputs of integrated operational amplifier IC, between the output of integrated operational amplifier IC and rectifier Z out-put supply, be connected in series the coil of relay K A, be serially connected in the control loop of contactor KM with the contact KA1 of relay K A.The control loop of contactor KM is often to open button SB11 to be connected in series normally closed button SB2 and contactor KM coil and thermal relay contact FR, often opening the two ends of button SB1 and connecing the self-locking circuit that the normal opened contact KM1 by bidirectional triode thyristor SCR serial connection contactor KM forms, the control signal of the bidirectional triode thyristor SCR control utmost point is connected in series by resistance R 4 and connects power supply behind the normally closed contact KA1 of relay K A and provide.Between the negative power end that meets positive power source terminal and rectifier Z of relay K A coil and be connected to capacitor C 6.

The utlity model has that volume is little, in light weight, easy for installation, reliable operation, advantage such as highly sensitive, applied widely, its voltage sampling point can be at the input of power transformer output or the used power supply of low-voltage electrical apparatus.For example the voltage sampling point is located at the end of incoming cables of motor, thereby has avoided except that the power supply phase failure, and the real open phase protection of carrying out asynchronous motor is made in the tripping after the phase failure of having opened circuit owing to contacts of contactor loose contact or thermal relay thermal source spare.Be applicable to the open phase protection of 380 volts of three-phase four-wire system AC low-tensions of voltage electrical equipment.

Fig. 1 is the utility model circuit theory diagrams.

Fig. 2 is the contactor control circuit figure that the utility model is used for Electric Machine Control.

Fig. 3 is the motor main circuit schematic diagram that the utility model is used for Electric Machine Control.

Below in conjunction with accompanying drawing the utility model is described in further detail: embodiment explains with the alternating current motor phase failure protector.

From accompanying

drawing

1,2,3 as can be seen, 3 of A ' B ' C ' are connected to the end of incoming cables (or on three phase mains) of threephase asynchronous respectively, when motor is accepted the three-phase line voltage operate as normal, the mid point N ' of capacitor C 1--C3 locates no-voltage (or very little), be input to integrated circuit (IC) " 2,3 " end voltage very little, even no-voltage, at this moment the signal that IC " 2,3 " pin inspection is picked up is through the comparison of its inside, automatically differentiate (considering the drift of zero line current potential), the IC ignore instruction can not moved.Integrated operational amplifier IC can adopt LM386.(or the main contacts loose contact of A.C. contactor KM when the three phase mains phase failure; the pyrogen part open circuits of thermal relay etc.) midpoint potential of C1-C3 changes rapidly; to produce one to zero line enough makes IC send the operation voltage (about 9V) of action command; this voltage is by bridge rectifier; filtering; after the voltage stabilizing; again by IC " 2; 3 " this voltage signal that the pin inspection is picked up compares; after the amplification; by the cut-off state upset is conducting state; driving relay K A moves its normally closed contact KA1 and disconnects the control utmost point of bidirectional triode thyristor SCR; make silicon symmetrical switch lose trigger voltage and turn-off; thereby cut off the power control circuit of motor; force A.C. contactor to discharge; disconnect main power source; make motor break away from power supply and shut down, motor is carried out protection.

This protector is after phase failure signal is picked up in inspection, and snap action, sensitivity are high, and action is clear-cut.Because being the control utmost point that is serially connected in bidirectional triode thyristor, the contact of relay carries out original paper as direct, so contact no-spark when action has prolonged the relay life-span with bidirectional triode thyristor." 1 " of IC, " 8 " end short circuit, " 4 " termination power negative pole, the output of IC " 5 " are succeeded electrical equipment KA coil one end, another termination positive source end of relay K A coil, on relay K A coil and meet diode D6, be used for the electromagnetic energy that release relay KA coil is stored.

Operation principle:

Close a switch behind the QS, three-phase alternating-current supply adds by FU and causes A.C. contactor KM upper end, its control loop of while gets electric, at this moment presses start button SB1, because of relay K A normally closed contact is connected on bidirectional triode thyristor SCR control loop, SCR is when pressing SB1, get a triggering signal and conducting, so KM gets its auxiliary normally open contact KA1 self-locking of electrode merga pass, supply voltage is added to thermal relay FR by the KM of adhesive, be added to motor M by FR again, make M get electric normal operation.

A ' B ' C ' is connected to the motor end of incoming cables, constitute a point detection signal by its mid point N ' after the C1--C3 step-down and electrical network zero line N, when a certain when mutually the phase failure taking place, current potential raises rapidly between N ' and the N, (just often N '-N voltage be zero) this voltage by after the Z rectification by C4 filtering, after the D5 voltage stabilizing, provide the direct voltage that detects about the one about 7V of loop, this voltage carries out being input to after the dividing potential drop " 2,3 " pin of IC by R1, R2, R3, the W that is connected into bridge type return.Because this integrated package inside has " ,-" input function the signal of external circuit input is compared, amplify the back and export low level driving relay K A adhesive by " 5 " pin, its normally closed contact disconnects the control utmost point of bidirectional triode thyristor, make bidirectional triode thyristor SCR Triggerless and end, thereby disconnect the control voltage circuit of KM, the KM outage is discharged, and its main contacts KM2 cuts off the major loop of motor M, and M is shut down.The effect of D6 is the high voltage protection KA that is produced when suppressing the folding of KA, and C6 is the alternating component in the further filtering loop.

This protector adopts unique voltage sampling type design, will change accordingly with the wiring group of motor and the different generations of field pole logarithm at its three phase terminals voltage after the motor phase failure.This protector is exactly that motor three phase terminals voltage after utilizing this principle to the phase failure is taken a sample, compares, amplified, and makes its action thereby reach rapid disconnection control loop, and cutting off major loop is that motor breaks away from the purpose that power supply reaches protection.

This protector can adapt to the three-phase AC asynchronous motor of arbitrary power, arbitrary number of poles in the 380V system; be not subjected to the current affects of motor; though this protector is the voltage sampling type; but the normal operation that can differentiate line voltage automatically allows fluctuation range, does not cause protector because of the line voltage transient fluctuation misoperation to take place.

This protector has been used the integrated circuit of modern advanced technologies making as its core, makes circuit greatly simple, because integrated circuit has high reliability, makes this protector have higher sensitivity.

This protector is applicable to ambient temperature at-5 ℃～+ 45 ℃, and relative humidity is not more than 85% environmental work.

This protector is not before the phase failure takes place in power supply (motor end of incoming cables); consumed power is atomic (can ignore); even also just relay snap action power consumption after the phase failure takes place, its power atomic (through after the actual measurement phase failure about the about 25MA of power consumption) can play real purpose of energy saving.

Claims

1; a kind of phase failure protector; it comprises rectification; filtering; voltage stabilizing circuit; it is characterized in that capacitor C 1 by Y-connection; C2; the C3 electricity connects three phase mains; be connected in series the rectifier Z in the rectification filtering voltage stabilizing circuit between its neutral point N ' and the zero-power line N; on the rectification filtering voltage stabilizing circuit dc output end and connect by resistance R 1; R2; R3; the resistance bridge that potentiometer W forms; two dividing potential drop output electricity of this resistance bridge connect two inputs of integrated operational amplifier IC; between the output of integrated operational amplifier IC and rectifier Z out-put supply, be connected in series the coil of relay K A, be serially connected in the control loop of contactor KM with the contact KA1 of relay K A.

2, according to the described protector of claim 1; the control loop that it is characterized in that contactor KM is often to open button SB1 to be connected in series normally closed button SB2 and contactor KM coil and thermal relay contact FR; often opening the two ends of button SB1 and connecing the self-locking circuit that the normal opened contact KM1 by bidirectional triode thyristor SCR serial connection contactor KM forms, the control signal of the bidirectional triode thyristor SCR control utmost point is connected in series by resistance R 4 and connects power supply behind the normally closed contact KA1 of relay K A and provide.

3,, it is characterized in that between the negative power end that meets positive power source terminal and rectifier Z of relay K A coil and be connected to capacitor C 6 according to the described protector of claim 1.