CN2313320Y

CN2313320Y - Electronic over-current protector

Info

Publication number: CN2313320Y
Application number: CN 97230595
Authority: CN
Inventors: 钟理彰
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-12-18
Filing date: 1997-12-18
Publication date: 1999-04-07
Anticipated expiration: 2007-12-18

Abstract

The utility model discloses an electronic over-current protector, which is used for electrical appliances and particularly for the over-current protection of motors. The utility model is composed of a current transformer LA, a rectifying diode D < 1 >, a shunt resistor R, a capacitor C, a voltage stabilization diode DC, a controlled silicon SCR and a relay J. The utility model has good anti-interference ability, the utility model has reliable over-current protective performance for electrical appliances and especially motors, and besides, the utility model has the advantages of simple structure, low cost, high precision and convenient installation.

Description

The electronic overcurrent protection device

The utility model relates to and be applicable to electrical equipment, particularly the electronic overcurrent protection device of motor overcurrent protection.

At present, overcurrent protection when electrical equipment, motor operation, widely used is that thermal relay is realized, but is subjected to the thermal source interference of non-signal in the thermal relay use easily, mechanical adjustment has error, often is difficult to accurately play the effect of overcurrent protection.Thereby design anti-interference, dependable performance, operation precision height, simple in structure, easy for installation, cheap electronic overcurrent protection device, be of great value.

The purpose of this utility model is a kind of simple in structure, dependable performance of design, operation precision height, cheap electronic overcurrent protection device.

For achieving the above object; the utility model has been taked such measure: the electronic overcurrent protection device; by the current transformer LA that can induce alternating voltage by secondary after the principal current; rectifier diode D1 and divider resistance R with excess voltage protection; capacitor C; voltage stabilizing didoe DW; controllable silicon SCR and relay J are formed; the end of current transformer LA is connected with the positive pole of rectifier diode D1; the negative pole of rectifier diode D1 is connected with the end (1) of divider resistance R; current transformer LA; the other end of the other end and divider resistance R (2); one end (8) of the negative pole of capacitor C and relay J connects; the positive pole of the movable tap of divider resistance R (3) and capacitor C; voltage stabilizing didoe DW negative pole (4) and controllable silicon SCR anode (5) connect; the negative electrode of controllable silicon SCR (6) is connected with the relay J other end (7), and its control utmost point (10) is connected with the positive pole (9) of voltage stabilizing didoe DW.

Adopt the good antijamming capability of the utlity model has of above measure, overcurrent protection dependable performance during to the operation of the special motor of electrical equipment, circuit structure is simple, accuracy is high, easy for installation, cost is low, the utility model has bigger development potentiality.

The utility model is described in further detail below in conjunction with drawings and embodiments:

Fig. 1 is circuit theory diagrams of the present utility model;

Fig. 2 is the circuit theory diagrams of another execution mode of the utility model.

As shown in Figure 1; the utility model mainly is made up of the current transformer LA and the excess voltage protection that can induce alternating voltage by secondary after the principal current; and excess voltage protection is by rectifier diode D1; capacitor C; voltage stabilizing didoe DW; controllable silicon SCR and relay J are formed; following annexation is arranged between them: the end of current transformer LA is connected with the positive pole of rectifier diode D1; the negative pole of rectifier diode D1 is connected with the end (1) of divider resistance R; the other end of the current transformer LA other end and divider resistance R (2); the negative pole of capacitor C and relay J one end (8) connect; the positive pole of divider resistance R movable tap (3) and capacitor C; voltage stabilizing didoe DW negative pole (4) and controllable silicon SCR anode (5) connect; silicon controlled negative electrode (6) is connected with the relay J other end (7); its control utmost point (10) is connected with the positive pole of voltage stabilizing didoe DW, and the normally-closed contact of relay J is connected with the control circuit of motor A.C. contactor.When motor normally moves, main circuit just has electric current to pass through, use single-phase motor or using threephase motor and under the situation of three-phase equilibrium, the secondary that is connected to the current transformer LA of main circuit AC side induces alternating voltage, after rectifier diode D rectification, be added on the divider resistance R, divider resistance R is positioned at the voltage adjustment under the voltage stabilizing value of voltage stabilizing didoe DW and charges to capacitor C.The main circuit operating current just often, the voltage that is added on voltage stabilizing didoe DW is lower than its voltage stabilizing value, can not send triggering signal to controllable silicon SCR, controllable silicon SCR is in off state, relay J is failure to actuate.When motor overload operation or other reason cause that operating current is excessive; the alternating voltage that current transformer LA induces also increases; direct voltage after the process rectifier diode D1 rectification is also along with rising; the charging voltage at capacitor C two ends is greater than the voltage stabilizing value of voltage stabilizing didoe DW at this moment; voltage stabilizing didoe DW punctures the back and sends triggering signal to controllable silicon SCR; make the controllable silicon SCR conducting; under the energy of capacitor C; the relay J action; its normally-closed contact is opened; make the control circuit outage of A.C. contactor CJ and trip, the power supply of sever supply motor and shielding.

Be used in when the utility model under the situation of threephase motor and three-phase current unbalance; also can implement alternatively; as shown in Figure 2; the utility model of this execution mode is by the mutual device LA of the electric current that is added on the main circuit AC side; LB; LC and excess voltage protection are formed; and excess voltage protection is by rectifier diode D1; D2; D3; capacitor C; voltage stabilizing didoe DW; controllable silicon SCR and relay J are formed; D.C mutual-inductor LA; LB; the end of LC respectively with rectifier diode D1; D2; the positive pole of D3 connects; rectifier diode D1; D2; be connected with the end 1 of divider resistance R after the negative pole parallel connection of D3; current transformer LALB; after the parallel connection of the LC other end with the other end 2 of divider resistance R; the negative pole of capacitor C and relay J one end 8 connect, and the connected mode of all the other elements is the same with connected mode shown in Figure 1.When the main circuit operating current just often, its operation principle is the same with execution mode shown in Figure 1.When the operating current of any phase on the main circuit is excessive; can correspondingly make current transformer LA or LB or LC induce the alternating voltage that increases; through becoming the direct voltage that has raise after rectifier diode D1 or D2 or the D3 rectification; the charging voltage at capacitor C two ends is greater than the voltage stabilizing value of voltage stabilizing didoe DW at this moment; voltage stabilizing didoe DW punctures the back and sends triggering signal to controllable silicon SCR; make the controllable silicon SCR conducting; under the energy of capacitor C; the relay J action; its normally-closed contact is opened; make the control circuit outage of A.C. contactor CJ and trip, sever supply motor power and shielding.

Claims

1, electronic overcurrent protection device; form by the current transformer LA and the excess voltage protection that can induce alternating voltage by secondary after the principal current; the positive pole of rectifier diode D1 in an end that it is characterized in that current transformer LA and the excess voltage protection is connected, and an end (2), the negative pole of capacitor C and the end (8) of relay J of the divider resistance R in the other end and the excess voltage protection are connected.

2; protector according to claim 1; it is characterized in that described excess voltage protection is by rectifier diode D1; divider resistance R; capacitor C; voltage stabilizing didoe DW; controllable silicon SCR and relay J are formed; rectifier diode D1 is connected with the end (1) of divider resistance R; the negative pole of the other end of divider resistance R (2) and capacitor C; one end (8) of relay J connects; the positive pole of the movable tap of divider resistance R (3) and capacitor C; the anode (5) of the negative pole of voltage stabilizing didoe DW (4) and controllable silicon SCR connects, and the negative electrode of controllable silicon SCR (6) is connected with an other end (7) of relay J.

3, protector according to claim 1, that it is characterized in that inducing alternating voltage can be three current transformer LA, LB, LC, can be three rectifier diode D1, D2, D3 and be attached thereto what connect respectively.