CN2291737Y

CN2291737Y - Three-phase machine protector

Info

Publication number: CN2291737Y
Application number: CN 94204409
Authority: CN
Inventors: 陈春贵
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-02-26
Filing date: 1994-02-26
Publication date: 1998-09-16
Anticipated expiration: 2004-02-26

Abstract

The utility model discloses a three-phase motor protector with a simulation test current circuit. The utility model is characterized in that in the circuit of the protector of the prior art which is composed of a sampling circuit, an overload protection circuit, an executive circuit and a power supply circuit, the connecting point of the sampling circuit and the overload protection circuit is additionally connected with a simulation test current circuit. The simulation test current circuit can simulate the sampling signal, and a current meter displays the corresponding simulation current which is used for accurately calibrating and setting the protection value. The ammeter is used for observing the operation situation of the motor at ordinary times.

Description

A kind of three-phase motor protector

The utility model relates to a kind of electric equipment protecting means, more particularly belongs to three-phase motor protector.

As everyone knows, three phase electric machine and other electric equipment in use damage motor and are typically equipped with overcurrent protector for preventing overload.But this class protector has a deficiency, if need do conventional verification, the work of adjusting, must use special-purpose current feedback circuit.Complex operation not only, and general user does not have.So the reference data and the estimation that can only rely on protector to indicate are sometimes carried out verification, are adjusted, cause poor reliability, precision low, consequently, or motor shuts down under normal duty changes, or can not get protection under the overload situations.

Task of the present utility model provides a kind of three-phase motor protector, the not only verification of this protector, the convenience of adjusting, and can also observe the motor operating current value.

Task of the present utility model is realized by following technical proposals:

By sample circuit, overload protecting circuit, in the prior art three-phase motor protector circuit structure that executive circuit and power circuit are formed, increase in the junction of sample circuit and overload protecting circuit and to have connect an analogue test current circuit.This circuit can analog sampling signal, shows the current value of corresponding analog sampling signal on ammeter, and is defeated by overload protecting circuit with the form of voltage, carries out amplitude discrimination, reaches the purpose of protection motor.

Simulation experiment circuit, by partial pressure potential device W1, voltage to current converter and ammeter are formed; Voltage to current converter comprises voltage attenuation network W2, R7, R8, R9 and single amplifier IC4, and zero potentiometer W3, feedback resistance R11, potentiometer W4.Two of W1 are the termination current/voltage fixedly, and the adjustable side links through the contact of isolating diode D16 and sample circuit output, overload protecting circuit and voltage to current converter.3 pin of single amplifier IC4 and an end of voltage attenuation network join, and IC4 output 6 pin connect ammeter through current-limiting resistance R10, and the other end of ammeter links to each other with the contact of parallel resistor R11, potentiometer W4 and IC42 pin; The other end ground connection of R11 and W4,2,3 pin of IC4 are connected to two reverse protection diode D17, D18.

The utility model compared with prior art owing to set up the analogue test current circuit, makes protector itself possess test, verification and setting function, thus strengthened inspection to protector, guaranteed the normal operation of motor.Moreover ammeter can intuitively show the motor operating current value, can observe motor running condition easily.

The utility model is described further by embodiment below in conjunction with accompanying drawing.

Fig. 1 is the utility model functional-block diagram;

Fig. 2 is the utility model circuit theory diagrams.

See Fig. 1, comprise sample circuit 1, analogue test current circuit 2, overload protecting circuit 3, executive circuit 4, power circuit 5 is formed.Wherein sample circuit 1, and overload protecting circuit 3, executive circuit 4 are connected successively, and analogue test current circuit 2 is connected on the tie point of input of the output of sample circuit 1 and overload protecting circuit, and power circuit 5 is for each several part provides positive and negative 12 volts of voltages.

Fig. 2 is this practical novel circuit schematic diagram.A, B, C are three independently mutual inductor coils in the sample circuit 1, and its lead-out wire connects the input of bridge rectifier respectively, and the bridge rectifier output accesses sample capacitor C 1, C2, C3, reach sampling resistor R4, R5, R6; Diode D13, D14, D15 play buffer action, and its positive pole also connects the back output of sample circuit that is; Resistance R 1, R2, R3 are shunt resistance, also are ammeter range resistance.Lead L1, L2, L3 are used for short circuit mutual inductor coil A, B, C, any two-phase instrument transformer of short circuit, and ammeter can show another phase current values.

During work, mutual inductor coil is set on three motor power-supply wires, respectively three-phase current is sampled, take out the voltage signal of a maximum phase, the one tunnel send the analogue test current circuit, carries out the U-I conversion, on ammeter, show current value, be used to observe motor ruuning situation.Overload protecting circuit 3 is delivered on another road, carries out amplitude discrimination, to realize the protection to motor.

Analogue test current circuit 2; comprise partial pressure potential device W1; isolate diode D16; voltage attenuation network W2, R7, R8, R9, protection diode D17, D18, operational amplifier IC4; zero potentiometer W3; feedback resistance R11 and W4, current-limiting resistance R10, ammeter A (present embodiment is selected pointer ammeter for use).Regulator potentiometer W1, from voltage source 5, take out continuously adjustable voltage magnitude, by isolating diode D16, one the tunnel through the voltage attenuation network, operational amplifier U-I conversion, on ammeter, obtain O to the continuously adjustable current amplitude of full scale, simulate the voltage signal of sending here from sample circuit, through the current value of this operational amplifier U-I conversion demonstration.And another road is the same with sample circuit 1, delivers to overload protecting circuit 3 and carries out amplitude discrimination.

Because so the electric current of amplifier IC4 output is a constant-current source, can seal in several kilohms resistance, is used for current limliting, the neither ammeter that undermines during by big electric current and short circuit with assurance institute survey line road.

Overload protecting circuit 3 (comprising open phase protection); this part circuit comprises two voltage comparators that reference voltage is different; to obtain two kinds of overload protections that the length delay time is different; the comparator of how different reference voltages also can be set, to obtain the delay protection of even more ideal over-load inverse time-lag characteristic.

DW1 is a voltage-stabiliser tube in the overload protecting circuit, and R12, R13, R15, R16 are the reference voltage divider resistance, are used to set up the reference voltage of voltage comparator ic 1, IC2, and the reference voltage of IC2 is greater than the reference voltage of IC1.

Following division utilizes analog signal that three steps of setting value are set: 1. regulate potentiometer W1 in the analogue test current unit; dividing potential drop is taken out voltage signal; the U-I conversion of amplifier IC4 of leading up to shows electric current in ammeter; suppose and be adjusted to required protective current value I place; then the correspondent voltage signal is delivered to overload protecting circuit 3; regulate W5 and make the upset of IC1 voltage comparator logic just, LED1 extinguishes simultaneously, and the LED2 Light-Emitting Diode is lighted.The output 1 pin anticathode that is IC1 is high level from the low level jumping, and output current charges to Ct by R17, R19.The desirable higher value of the resistance of R19, the time that makes Ct be charged to design load is that 5-20 minute scope is interior adjustable, does the protection of underloading long delay; 2. regulating W1 makes current value show 1.2 times that are about former setting value, the upset of IC2 voltage comparator logic, the output 7 pin anticathodes of IC2 are jumped from low level and are high level, output current charges to Ct by less charging resistor R18, W6, and it is that 3-20 is adjustable second that adjusting W6 makes Ct be charged to the design load time.3. when adjusting W1 made analog current less than setting value, then IC1 and IC2 output anticathode were low level, and the electric charge of Ct is by discharge resistance R17 discharge, and LED2 goes out simultaneously, and LED1 is bright.Normally in service, the voltage signal that takes out from sample circuit 1 replaces analog signal, has identical effect.

Performance element 4 is by voltage comparator ic 1, triode BG1, and compositions such as relay J, R20 and DW2 are used to set up the reference voltage of voltage comparator ic 3.When the voltage on the Ct reaches design load, the upset of IC3 voltage comparator logic, the BG1 conducting, the relay J action, string disconnects at the normally-closed contact of control electric motor loop, the motor outage.

IC1, IC2, IC3 adopt four high guaily unit integrated circuit LM324, and IC4 adopts single amplifier F007.

Claims

1, a kind of three-phase motor protector; circuit part comprises sample circuit (1), overload protecting circuit (3), executive circuit (4) and power circuit (6); it is characterized in that:, also be connected to an analogue test current circuit (2) on the tie point of overload protecting circuit (3) in sample circuit (1).

2, three-phase motor protector according to claim 1 is characterized in that: simulation experiment circuit (2) is by partial pressure potential device W1, and voltage to current converter and ammeter are formed; Voltage to current converter comprises voltage attenuation network W2, R7, R8, R9 and single amplifier IC4, and zero potentiometer W3, feedback resistance R11, and potentiometer W4.Two of W1 are the termination supply voltage fixedly, and the adjustable side links through the contact of isolating diode D16 and sample circuit (1) output, overload protecting circuit (3) and voltage to current converter, and 3 pin of single amplifier IC4 and an end of voltage attenuation network join.IC4 output 6 pin connect ammeter through current-limiting resistance R10; The other end of ammeter and parallel resistor R11.The contact of 2 pin of potentiometer W4 and IC4 links, the other end ground connection of R11 and W4, and 2,3 pin of IC4 are connected to two reverse protection diode D17, D18.