CN2246864Y

CN2246864Y - Open-phase and over-load protection of three-phase asynchronous motor

Info

Publication number: CN2246864Y
Application number: CN 95207870
Authority: CN
Inventors: 张选平
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-04-06
Filing date: 1995-04-06
Publication date: 1997-02-05
Anticipated expiration: 2005-04-06

Abstract

The utility model relates to a phase interruption and overloading protective device for a three-phase asynchronous motor. The utility model is composed of a current transformer, a rectifier tube, a triode, a relay, a loudspeaker and a luminous diode, the collector of the triode is connected with the relay, the alarm loudspeaker which is connected in parallel with the normally closed contact of the relay, the luminous diode, etc., and the utility model can cut off a power supply and sent out acoustic-optical alarm when the three-phase asynchronous motor generates a fault. The utility model has the advantages of reasonable design, convenient fabrication, stable operation and low power consumption, and therefore, the utility model is an ideal protective device for phase interruption and overloading protection of the three-phase asynchronous motor.

Description

Threephase asynchronous overload of loss of phase protective device

The utility model relates to the overload of loss of phase protective device of threephase asynchronous, particularly a kind of overload of loss of phase protective device that is applicable to automatic start-stop class motor.

Existing motor protecting device mostly adopts thermal relay and overcurrent relay to limit winding current, and action error is big, and the phase failure and overload protection function are poor, and be often malfunctioning in electric motor protecting.So the protective device of various motor occurred; as disclosed overload of loss of phase protector in the Chinese patent 87205604; though some improvement is arranged, can play certain protective role, this protector is used for the relay of control circuit; not only contact rating is little; and be normal opened contact, only could be closed after the motor operation, so wiring is very inconvenient; start and stop that can not the individual inspiration control loop more can not adapt to the motor overload of loss of phase protection in automatic start-stop loop.

The purpose of this utility model is the shortcoming that will overcome above-mentioned protective device; and a kind of control contact is provided is normally closed; and with existing thermal relay wiring, the identical threephase asynchronous overload of loss of phase protective device of installation; so that it is accurate more, rapid, and convenient to the overload of loss of phase protection of motor.

Solution of the present utility model comprises power supply, current transformer TAa, TAb and TAc, rectifying tube D1, current-limiting resistance R7, triode V3, relay J, loud speaker S and light-emitting diode D7, it is characterized in that current transformer TAa, TAb, TAc connect mutually, be connected to the base stage of triode V3 by rectifying tube D1 and current-limiting resistance R7, be connected to the relay J of band normally closed contact J1 on the collector electrode of triode V3, loud speaker S and light-emitting diode D7 are in parallel with normally closed contact J1; Be connected to the overload protecting circuit of forming by the capacitor C 2 on complementary triode V1, V2 and the V1 base stage between rectifying tube D1 and current-limiting resistance R7.

The emitter of triode V2 links to each other with current-limiting resistance R7 in this device; The base stage of triode V1 links to each other with rectifying tube D1 by fixed resistance R4 and potentiometer R2

This device is connected to the bridge-type rectifier of being made up of capacitor C 4, C5 and silicon bridge D4 on the collector electrode of triode V3, provide power supply to give triode V3.String has diode D6 and a resistance R 9 in the circuit of loud speaker S and light-emitting diode D7, as loud speaker S and the light-emitting diode D7 power supply when the accident alarming.

Describe embodiment of the present utility model in detail below in conjunction with accompanying drawing.

Fig. 1 is the schematic circuit of threephase asynchronous overload of loss of phase protective device.

Fig. 2 is the external cabling schematic diagram of this device.

Referring to Fig. 1, be connected on three current transformer TAa in the protector housing, its connection of TAb and TAc is an open-delta.When electric motor normal working, current transformer can generate triple-frequency harmonics, and voltage stack is added on the base stage of triode V3 after rectifying tube D1 rectification by current-limiting resistance R7.Triode V3 is the control triode, and its collector electrode operating voltage is provided by the bridge rectifier that capacitor C 4, C5 and silicon bridge D4 form.Power supply is introduced by the A on the casing, B terminal.Because of the V3 base stage is a positive voltage, so it is in the saturation conduction state, thereby make with it and the relay J short circuit that connects, no current in the relay, and the contact J1 that links to each other with motor control loop is a normally closed contact, so normal operation circuit.After motor generation phase failure accident, the third harmonic voltage sum that its TAa, TAb, three current transformers of TAc are inducted reduces to 0 immediately, at this moment the base voltage of triode V3 also reduces to 0, thereby cause V3 to end, the direct voltage at silicon bridge D4 two ends makes the relay J action, and its normally closed contact J1 disconnects.Rectifier power source is formed by capacitor C 6, resistance R 8 and silicon bridge D5 in normally closed contact J1 two ends, makes relay J keep off-state.Simultaneously voltage makes loud speaker 8 and light-emitting diode D7 get electric and reports to the police through D6, R9, produces acousto-optic and shows.If motor generation overload situations, the third harmonic voltage sum that three current transformers are inducted is given capacitor C2 charging through rectifier diode D1, potentiometer R2, resistance R 4, after surpassing specified negative the cutting of motor, the voltage accumulation make triode V1 and V2 transfer saturation conduction to by ending, and make control triode V3 base stage dead electricity and ending, the result makes relay J get electronic work, normally closed contact J1 disconnects, and motor stops, and keeps off-state until relay is resetted always.

Referring to Fig. 2, the profile of this protective device and the mode of connection are all identical with the ordinary hot relay.Wherein 1,2,3 is the three phase mains terminal, and 4 is to transship the knob of adjusting, the 5th, and housing, the 6th, the sound and light alarm demonstration, the 7th, the control end normally closed contact, 8 is installing hole.

Compare with existing protector, this device can make threephase asynchronous cut disconnected reaching mutually The time, rapid deenergization and accompany by sound and light alarm reliably, sign is obviously. This protective device can Move in less than 1 second time at disconnected phase time. Overload time is the inverse time lag, and is better than other guarantor Protect the overload characteristic of device. This circuit is simple, reliable and stable work, and wiring and installation are all with common Electrothermal relay is identical, and easy-to-connect is convenient to adapt to and grasp. This device is particularly suitable for automatically The motor protection of start stop system has very big market potential. Real is at present best electricity of China Protector.

Claims

1, a kind of threephase asynchronous overload of loss of phase protective device, comprise power supply, current transformer TAa, TAb and TAc, rectifying tube D1, current-limiting resistance R7, triode V3, relay J, loud speaker S and light-emitting diode D7, it is characterized in that current transformer TAa, TAb and TAc connect mutually, be connected to the base stage of triode V3 by rectifying tube D1 and current-limiting resistance R7, be connected to the relay J of band normally closed contact J1 on the collector electrode of triode V3, loud speaker S and light-emitting diode D7 are in parallel with normally closed contact J1; Be connected to the overload protecting circuit of forming by the capacitor C 2 on complementary triode V1, V2 and the V1 base stage between rectifying tube D1 and the current-limiting resistance R7.

2, protective device as claimed in claim 1 is characterized in that the emitter of triode V2 links to each other with current-limiting resistance R7; The base stage of triode V1 links to each other with rectifying tube D1 by fixed resistance R4 and potentiometer R2.

3, protective device as claimed in claim 1 or 2 is characterized in that being connected to the bridge-type rectifier of being made up of capacitor C 4, C5 and silicon bridge D4 on the collector electrode of triode V3, provides power supply to give triode V3.

4, protective device as claimed in claim 1 or 2 is characterized in that in the circuit of loud speaker 8 and light-emitting diode D7 string has diode D6 and resistance R 9, as loud speaker S and the light-emitting diode D7 power supply when the accident alarming.

5, protective device as claimed in claim 1 or 2 is characterized in that rectifier power source is formed by capacitor C 6, resistance R 8 and silicon bridge D5 in the normally closed contact J1 two ends of relay J, makes relay J keep off-state.