CN2167468Y - Protective device for electric appliance - Google Patents

Abstract

The utility model provides an open-phase power cut protective device for a three-phase motor, mainly comprising a three-phase knife switch, relays and a common switch. The relays can be controlled by controlling the common switch to enable a motor to run or stop. The relays which are respectively connected with three phase lines mutually control the open-phase power cut of the three phase lines to protect the motor from burning due to open phase. The utility model has the advantages of simple structure, low cost, safety, long service life, convenient operation, etc., and is a necessarily matched electric apparatus for the three-phase motor.

Description

Protective device for electric appliance

The utility model relates to a kind of motor protecting device, especially a kind of threephase motor phase shortage power-off protector.

At present a lot of about the protective device kind of threephase motor; mainly contain overload protection and open-phase protection two big classes; wherein the protector of forming with the transistor electronic device is maximum; its weak point is that electronic component is short useful life; can not bear the Fraquent start of short time; fragile, the generation phase shortage loses the protection to electronic phase, makes the work of motor phase shortage burn out motor.

The purpose of this utility model provide a kind of simple in structure, cost is low, easily install not fragile, the motor phase failure protection device of long service life.

The purpose of this utility model realizes in the following manner.

On the power line of threephase motor, knife switch and relay are installed, wherein a relay is controlled the three-phase power line break-make of importing motor, the break-make of last pulling relay coil electric current of another relay control.Two relays are controlled mutually, jointly motor are produced open-phase protection.

Figure of description is a circuit diagram of the present utility model;

With reference to Figure of description the utility model is described in detail.

Phase-defect of motor power-off protector of the present utility model is mainly by Three-phase knife switch K, relay J₁, relay J₂And regular tap K₃Form, above-mentioned parts are all installed in the power distribution cabinet, and wherein Three-phase knife switch k and electrical network join, relay J₁Three groups of contact switch k_1－1k _1－2k _1－3Be serially connected in Three-phase knife switch and threephase motor between. Relay J₁Pull-in winding be connected on relay J₁The B, C line of contact switch between. And be connected in series simultaneously relay J₂Contact switch k₂ Relay J₂Pull-in winding be serially connected in relay J₁The A line and zero line of contact switch between, and the regular tap k that connects simultaneously₃。

Embodiment:

Motor phase shortage power-off protector of the present utility model very easy to use simple, during use, earlier the Three-phase knife switch closure, closed then regular tap k ₃, power line A line and zero line form the loop, make relay J ₂Pull-in winding adhesive k ₂Engage relay J ₁Pull-in winding, make power line B, C line through J ₁Pull-in winding form loop adhesive k _1-1k _1-2k _1-3Three groups of contact switchs make power line and motor connect motor work.

When the three phase network phase shortage, closed k ₃, protector of the present utility model just produces protective effect, k _1-1k _1-2k _1-3Can not connect, its protection process is: as the closed k of A phase line short of electricity ₃, J ₂Not adhesive.Contact switch k ₂Nature can not be closed, J ₁No current passes through k _1-1k _1-2k _1-3Three groups of contacts are not closed, even BC two phase lines have electricity can not enter motor.As any phase line short of electricity in B, C two phase lines, even the A phase line has electric J ₂Adhesive k ₂Make J ₁Conducting, but B, the short of electricity of C phase line can not form the loop, so J ₁Pull-in winding can not adhesive k _1-1k _1-2k _1-3Three groups of contacts can not be closed.Therefore motor is produced protection.

Phase-defect of motor power-off protector of the present utility model is compared with existing technology, and has structure Simply, the characteristics such as low, safe and reliable convenience of cost. Can avoid threephase motor because of the accident that phase shortage burns out fully, have good economic results in society.

Claims (4)

1, motor phase shortage power-off protector comprises Three-phase knife switch K, relay J ₁J ₂And regular tap K ₃Form Deng parts, it is characterized in that: Three-phase knife switch and relay join, and the pull-in winding of relay is connected on the three-phase power line.

2, protector according to claim 1 is characterized in that: relay J ₁Pull-in winding be subjected to relay J ₂Contact switch K ₂Control.

3, protector according to claim 2 is characterized in that relay J ₁Control three the contact switch K of self ₁₁K ₁₂K ₁₃Control the running of motor with this.

4, protector according to claim 1 is characterized in that: relay J ₂An end and the three-phase power line of pull-in winding join, the other end and common zero line join, middle serial connection K ₃

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