CN2133079Y

CN2133079Y - Automatic protector for ac. motor

Info

Publication number: CN2133079Y
Application number: CN 92216950
Authority: CN
Inventors: 吴铁辉
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-09-06
Filing date: 1992-09-06
Publication date: 1993-05-12
Anticipated expiration: 2002-09-06

Abstract

The utility model discloses an automatic protector for AC motor, which needs no external power supply and has the advantages of simple structure, low cost and high reliability. The utility model is composed of a power supply circuit which is composed of a rectifying bridge, a voltage stabilizing circuit and a filter and a sampling comparison circuit which is composed of a rectifying bridge, a filter adjustor and a voltage comparator, and the power supply circuit is connected with a running relay; the input ends of the power supply circuit and the sampling comparison circuit are respectively connected with the two coils of a current transformer; the output end of the sampling and comparison circuit is connected with the input end of an actuating mechanism, the normally open contact of the running relay is connected in series with the normally-closed contact of the relay of the actuating mechanism into a self-locking mechanism, and the input end of a comparator and the negative end of the power supply are connected with a delay circuit.

Description

Automatic protector for ac. motor

The utility model belongs to a kind of motor emergency protective device, particularly a kind of alternating current motor automatic protector.

Existing motor protector kind is a lot; generally all need a stabilized voltage power supply; and the power transformer cost height in the stabilized voltage power supply; in servicely very easily break down again; and existing current mode motor protector; generally be by stabilized voltage power supply; the current transformer and the shaping rectification circuit of three motor main circuit three-phase electricity signals that are used for taking a sample; balance adjusts circuit and OR circuit constitutes; when work; by three tunnel sampling three-phase electricity signals, be input to comparator respectively, restart actuator and work and realize the phase failure; the overload protection function; but because it adopts stabilized voltage power supply; increase cost, be prone to fault again, in addition; it adopts three instrument transformers and three tunnel shaping rectifications corresponding with it; balance is adjusted circuit; complex structure, the cost height, reliability reduces relatively.

The purpose of this utility model is to provide a kind of dispense with outer connecting power and then can save energy and alternating current motor automatic protector simple in structure, that cost is low, reliability is high.

The utility model is achieved in that it has an actuator; it also has one by rectifier bridge; a filter; the power circuit that voltage stabilizing circuit and secondary filter constitute; and constitute running control circuit with the operation relay that is connected on its two ends; it also has one by another rectifier bridge; the sampling comparison circuit that filtering adjuster and voltage comparator constitute; the power end of said comparator and reference edge link with the output of power circuit respectively; the input of the input of said power circuit and sampling comparison circuit links with two coils of current transformer respectively; and the output of the output of power circuit and sampling comparison circuit links with the power end of actuator and by current-limiting resistance and the diode that shields and the input of actuator respectively; and the normally-closed contact series connection of the normally opened contact of operation relay and the relay in the actuator; constitute self-locking mechanism, also be connected to the delay circuit that prevents this protector misoperation that electric capacity and resistance by parallel connection constitute at the input of above-mentioned comparator and power supply negative terminal.

According to above-mentioned motor protector; it also has a leakage protection circuit that is made of dividing potential drop adjustment circuit, another filter, rectifier, secondary filter and a voltage stabilizing circuit, and links by another current-limiting resistance and the diode that shields and the input of actuator.

Advantage of the present utility model is to adopt a current transformer and utilizes in the three-phase electricity not a power supply as this protector that links with start-up circuit, thereby dispense with outer connecting power, can reach energy-saving effect, and can make this protector circuit cast sealing, thereby be applicable to any occasion; In addition, adopt a current transformer to get an above-mentioned phase signals, can realize the high-low pressure phase failure, motor overload and earth leakage protective, thus simple in structure, cost is low and reliability is high.

Below in conjunction with drawings and Examples the utility model is elaborated:

Fig. 1 is a circuit block diagram of the present utility model;

Fig. 2 is electrical schematic diagram of the present utility model and winding diagram;

As shown in drawings, the utility model has a current transformer with two coil L1, L2, be connected to successively by rectifier bridge D1(1 at the first mutual inductor coil L1 two ends), a filter 2 constituting by filter capacitor C1 and resistance R 1, by voltage-stabiliser tube DW1, resistance R 2, ic chip 1(7812) and the voltage stabilizing circuit 3 of potentiometer W1 formation and the secondary filter 4 that constitutes by capacitor C 2, foregoing circuit constitutes power circuit; Be parallel with the luminous tube D3 and the current-limiting resistance R3 of operation relay J 1 and serial connection at the two ends 11 and 12 of power circuit, constitute running control circuit 5 and operation indicating circuit respectively; Be connected to successively by another rectifier bridge D2(6 at mutual inductor coil L2 two ends), the filtering adjuster 7 that constitutes by capacitor C 3 and potentiometer W4, by voltage comparator 8(IC2) (in the present embodiment for LM358) and be connected on the resistance R 6 of its input 21 and 22, the sampling comparison circuit that R8 constitutes, between comparator IC2 input 22 and power supply negative terminal 12, also be connected to the delay circuit that capacitor C 4 and resistance R 7 by parallel connection constitute, when preventing electric motor starting, this protector misoperation, pass through resistance R 5 at its output 26, the diode D8 that shields with by triode T, relay J 2 and diode D7 and resistance R 13, the input 10 of the actuator 9 that R14 constitutes links, the power end 13 and 14 of said actuator 9 links with the anode 11 and the negative terminal 12 of power circuit respectively, the power end 27 of said comparator IC2,28 and reference edge 23,24 two ends 11 and 12 anodes 11 that reach by potentiometer W2 and W3 and power circuit direct respectively and power circuit link, between another output 25 of comparator IC2 and power supply negative terminal 12, be in series with current-limiting resistance R4 and luminous tube D4, constitute overload indicating circuit; This protector also has a dividing potential drop that is made of resistance R 9～R11 and potentiometer W5 to adjust circuit; the other end 17 of said resistance R 10 is the earth terminal of this protector; adjust between the output 16 of circuit and the power supply negative terminal 12 in dividing potential drop and to be connected to a filter that constitutes by filter capacitor C5; the voltage stabilizing circuit that is connected to the rectification that constitutes by rectifying tube D5 and filter capacitor C6 and secondary filter at capacitor C 5 two ends and constitutes by voltage-stabiliser tube DW2; form leakage protection circuit; and link by current-limiting resistance R12 and the diode D6 that shields and the input 10 of actuator; the normally opened contact J1 of above-mentioned relay J 1 and the normally-closed contact J2 of relay J 2 series connection constitute self-locking mechanism.

In actual use; wiring as shown in Figure 2; above-mentioned self-locking mechanism is connected with the normally open contact CJ1 of contactor CJ; and constitute start-up circuit with button TA, QA and contactor C coil; and with A mutually with B mutually electricity link; and C is electric mutually as the primary side as instrument transformer, and the input 15 and the motor D casing of leakage protection circuit link.Press the button QA, motor D starting, power circuit gets electric, make relay J 1 electric, its normally opened contact J1 adhesive, and reach self-locking, the luminous indication of luminous tube D3 simultaneously by normally closed some J2;

1) the high pressure phase failure: A, B break mutually, contactor C dead electricity, and automatic cut-off motor D power supply stops motor D; High pressure C breaks mutually, no current, and also no current among the mutual inductor coil L1, then relay J 1 outage, its contact J1 disconnects, and makes contactor C coil losing electricity, and then motor D stops, and luminous tube D3 extinguishes simultaneously.

2) the low pressure phase failure, A, B wherein have broken string, the increasing of C phase current mutually mutually, mutual inductor coil L2 electric current strengthens, be input to comparator IC2 after the sampling, the output 25 of comparator IC2 and 26 output high level make actuator's 9 actions, normally closed some J2 of relay J 2 disconnects, make contactor C coil losing electricity, cut off main circuit power, motor D is stopped; If C breaks mutually, mutual inductor coil L1 no current then, this protector power cut-off, relay J 1 contact disconnects, and motor D is stopped.

3) motor overload:, behind the instrument transformer L2 sampling C phase current, be input to comparator IC2 once the motor overload three-phase current increases simultaneously, comparator IC2 output 25 and 26 output high level, make actuator's 9 actions, motor D is stopped, simultaneously the luminous indication of luminous tube D4.

4) earth leakage protective: if the motor electric leakage constitutes the loop by casing → bleeder circuit, leakage protection circuit output high level makes actuator's 9 actions, and normally-closed contact J2 disconnects, and motor D is stopped.

Claims

1; a kind of alternating current motor automatic protector; comprise actuator; it is characterized in that; it also has one by rectifier bridge (1); a filter (2); voltage stabilizing circuit (3); the power circuit that secondary filter (4) constitutes; and and the operation relay (J1) that is connected between its two ends (11 and 12) constitute running control circuit; it also has one by another rectifier bridge (6); the sampling comparison circuit that filtering adjuster (7) and voltage comparator (8) constitute; also be connected to the delay circuit that prevents this protector misoperation that constitutes by electric capacity (C4) and resistance (R7) between the input (22) of said comparator (8) and the power supply negative terminal (12); its power end (27 and 28) links with the positive-negative output end (11 and 12) of power circuit respectively; its reference edge (23 and 24) links by potentiometer (W2 and W3) and power positive end (11) respectively; the input of the input of said power circuit and sampling comparison circuit respectively with two coil (L1 of current transformer; L2) link; and the output (26) of output of power circuit (11 and 12) and sampling comparison circuit links with the power end (13 and 14) of actuator (9) and the input (10) by current-limiting resistance (R5) and diode (D8) that shields and actuator (9) respectively; and the normally opened contact of operation relay (J1) and the series connection of the normally-closed contact (J2) of the relay (J2) in the actuator (9) constitute self-locking mechanism.

2; alternating current motor automatic protector according to claim 1; it is characterized in that; it also have one by resistance (dividing potential drop that R9～R11) and potentiometer (W5) constitute is adjusted circuit; by be connected on dividing potential drop adjust between circuit output end (16) and the power supply negative terminal (12) a filter (C3) and by rectifying tube (D5); rectification that electric capacity (C6) constitutes and secondary filter reach the leakage protection circuit of being made up of the voltage stabilizing circuit of voltage-stabiliser tube (DW2) formation, and link by the input (10) of current-limiting resistance (R12) and diode (D6) that shields and actuator (9).

3, alternating current motor automatic protector according to claim 1 and 2 is characterized in that, is parallel with the luminous tube (D3) and the current-limiting resistance (R3) of serial connection at the two ends (11 and 12) of power circuit, constitutes the operation indicating circuit; Between another output (25) of comparator (IC2) and power supply negative terminal (12), be in series with current-limiting resistance (R4) and luminous tube (D4), constitute overload indicating circuit.