CN2088753U

CN2088753U - Electric motor protector

Info

Publication number: CN2088753U
Application number: CN 91205969
Authority: CN
Inventors: 徐国治
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-10
Filing date: 1991-04-10
Publication date: 1991-11-13

Abstract

The utility model relates to a phase interruption and overcurrent protective device for three-phase motor, which adopts a design scheme of adoption of an electric current detecting technology and non-adoption of a power supply transformer, and a controlled silicon ac switch is used to replace an electromagnetic actuating mechanism. The phase interruption and overcurrent protective device for three-phase motor is also comprises a rectification and filter link, an electric current setting link, an integral delay link, a DC electronic switch and a current-limiting and voltage-limiting circuit. The utility model has the advantages of simple device, high reliability, stable performance, wide control range of the motor, etc.

Description

Electric motor protector

Motor protection field under the present invention.

The motor protector that uses generally needs external power supply at present, and this has caused and has used inconvenience, complex circuit, and volume is big, cost is high, and extra power consumption.And executive component generally adopts relay, has mechanical displacement and wearing and tearing, and shortcomings such as electric spark ablation have influenced the sensitivity and the reliability of whole device.Especially the present protector that uses, the motor capacity scope of protection is little, and interchangeability is poor, has caused the inconvenience of selecting the appropriate protection device for use.

The objective of the invention is to make a kind of simple in structure, dependable performance, the protection capacity is big, and is easy to install, safeguards easily motor protector with low cost.In order to achieve the above object, the present invention is at arbitrary current transformer that is provided with mutually of threephase motor, and detection signal is controlled SCR AC switch after treatment again, to reach the protection purpose.

Below in conjunction with accompanying drawing the present invention is elaborated.

Fig. 1 is the protector schematic diagram, and Fig. 2 is the figure that installs and uses of protector.

As shown in Figure 1, protector is mainly by current detecting link, rectifying and wave-filtering link, current settings link, integrating circuit, electronic DC switch, current limiting pressure-limiting link, and the links such as alternating-current switch form.

The current transformer LH of current detecting link is used for detecting the electric current of the arbitrary phase of threephase motor, rectifier bridge D and the filter capacitor C of the signal of telecommunication that detects through over commutation, filtering link₁After, be defeated by the potentiometer W resistance R of current settings link₁, and the resistance R of integrating circuit₂Capacitor C₂ When load current when setting electric current, dc switch--controllable silicon T₁Current limliting, pressure limiting circuit are defeated by in not conducting, the signal of telecommunication that transformer LH detects after rectification, filtering, current limliting is by resistance R₃, pressure limiting is by diode D₁、D ₂Form, behind current limiting pressure-limiting, be defeated by T in the alternating-current switch₂The control utmost point, drive alternating-current switch, make the alternating-current switch conducting, keep in touch device adhesive motor and work on. When load current when setting electric current, the output voltage of rectification, filtering link is through current settings potentiometer W After the dividing potential drop, again by R₂、C ₂The integrating circuit time-delay that forms, promote the controllable silicon T1 of dc switch, make its conducting, because dc switch is connected to the output of rectifying and wave-filtering link, so behind dc switch conduction, the signal of telecommunication of rectifying and wave-filtering link output no longer is defeated by the current limiting pressure-limiting circuit by the dc switch short circuit, and just the signal of telecommunication drives controllable silicon T in the alternating-current switch never again₂, make like this controllable silicon T₂Turn-off at natural zero-crossing point. Control contactor discharges, and makes motor break away from electrical network.

Operation principle is such: behind motor starting, the signal of telecommunication by current transformer LH detects after rectification, filtering, divides two-way to be defeated by and sets potentiometer W, and the controllable silicon T of alternating-current switch ₂The control utmost point.When motor normally moved, load current was less than setting electric current, and the undertension that obtains after potentiometer W dividing potential drop is to reach controllable silicon T ₁The trigger voltage of the control utmost point, like this, as the controllable silicon T of dc switch ₁Still be in cut-off state, inoperative.And the signal of telecommunication of alternating-current switch is defeated by through pressure limiting in another road, and current limliting has been defeated by controllable silicon T after handling ₂The control utmost point, make its conducting, make contactor keep adhesive, motor continues operation.

When one of crosstalk current transformer disconnects mutually, because protector loses power supply, alternating-current switch is turn-offed at natural zero-crossing point, the contactor outage discharges.

When arbitrary in other two-phase disconnects mutually, or motor is during because of overload, stall, under-voltage overvoltage, because the result that line current increases, the signal of telecommunication after the rectification increases, and is higher than controllable silicon T after potentiometer W dividing potential drop ₁So the trigger voltage of the control utmost point is dc switch controllable silicon T ₁Conducting after the integrating circuit time-delay signal of telecommunication short circuit, makes the controllable silicon T of alternating-current switch ₂Signal out of hand discharges the contactor outage.

When avoiding starting, because of the rush of current misoperation, inserted integral element in the circuit, both overcome misoperation, make protector have anti-time limit characteristic again.

The present invention compared with prior art has simple in structurely, easy to use, and protection range is big, and the life-span is long, the characteristics that cost is low.

Fig. 2 installs and uses figure.

(1～60KW) major loop three phase mains directly passes the through wires hole of protector with motor.The pair of terminals of protector is sealed in control circuit, but then with regard to setting current.The over-current adjusting potentiometer is that setting current is big clockwise, is little counterclockwise.Before actuating motor, unclamp the lock nut of current calibration potentiometer, potentiometer is screwed into the end toward clockwise direction.Actuating motor makes motor operation reach full load condition, careful then and lentamente with potentiometer to rotation counterclockwise, make contactor coil outage tripping operation, again the potentiometer clockwise direction is changeed little by little, like this, repeat several times till no trip phenomenon last lock nut.

Claims

1, motor protector, by housing, lid, binding post, wiring board, instrument transformer constitute, and it is characterized in that the disposable injection molded of through wires hole and housing; Binding post is embedded in the housing; Wiring board comprises current detecting link, rectifying and wave-filtering link, current settings link, integration time delay process, electronic DC switch, current limiting pressure-limiting circuit, electronic AC switch.

2, by the motor protector of claim 1, it is characterized in that the current detecting link is made of a current transformer that is arranged at the arbitrary phase of threephase motor.

3, by the motor protector of claim 1, it is characterized in that the rectifying and wave-filtering link is by rectifier bridge D and capacitor C ₁Form.

4, by the motor protector of claim 1, it is characterized in that the current settings link is by potentiometer W and resistance R ₁Form.

5, by the motor protector of claim 1, it is characterized in that integrating circuit is by capacitor C ₂And resistance R ₂Form.

6, by the motor protector of claim 1, it is characterized in that electronic DC switch is by one-way SCR T ₁Form.

7, by the motor protector of claim 1, it is characterized in that current limliting, pressure limiting circuit are by resistance R ₃And diode D ₁, D ₂Form.

8, by the motor protector of claim 1, it is characterized in that electronic AC switch is by one-way SCR T ₂And diode D ₃～D ₆Resistance R ₄And piezo-resistance Rr forms.