CN102394488A

CN102394488A - Open-phase protection circuit of motor

Info

Publication number: CN102394488A
Application number: CN2011103479616A
Authority: CN
Inventors: 尹洪珠
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-11-07
Filing date: 2011-11-07
Publication date: 2012-03-28

Abstract

The invention discloses an open-phase protection circuit of a motor, which comprises a motor in star connection with a triphase AC power supply. An air circuit breaker QF and a thermorelay FR are connected in series between the motor and the triphase AC power supply, a capacitor C1 and a relay KA coil are connected in series between a neutral point and a neutral wire of the motor, which are in star connection, a relay KA normally closed contact, a contactor KM coil and a start button SB are connected in series between one of three phases of live wires connected with the motor and the neutral wire, and a contactor KM normally open contact is connected in series between the motor and the triphase AC power supply. The open-phase protection circuit of the motor has the benefits of simpleness, convenience in connection with an original circuit, lower cost and fast and reliable action, and can effectively prevent the motor from being damaged due to open phase.

Description

A kind of motor open-phase protection circuit

Technical field

The present invention relates to a kind of motor open-phase protection circuit.

Background technology

For three phase electric machine commonly used in life, phase-deficient operation is one of major reason that causes burn-down of electric motor.Special phase-lacking protective device is used in the startup operation circuit of large-size machine more, generally uses zero sequence current mutual inductor to carry out open-phase protection, but generally adopts the product of foreign import, and its cost is higher, and circuit connects cumbersome.And short circuit and overload protection only be equipped with, for most middle and small motor.When circuit had short trouble, air circuit QF can jump disconnected, and during overload, bigger electric current can make thermal relay FR action, thereby makes contactor KM coil losing electricity, plays a protective role.And work as motor in running, when causing the phase shortage phenomenon to take place for a certain reason, motor will soon be burnt.

Summary of the invention

Be technical deficiency more than solving, it is simple to the invention provides a kind of circuit, and cost is low, service-strong motor open-phase protection circuit.

The present invention realizes through following measure:

A kind of motor open-phase protection circuit of the present invention comprises motor, the motor Y-connection on three-phase alternating-current supply,

Be in series with air circuit QF and thermal relay FR between motor and the three-phase alternating-current supply; Be in series with capacitor C 1 and relay K A coil between the neutral point of motor Y-connection and the zero line; Motor connects one in the three-phase firewire and is in series with relay K A normally-closed contact, contactor KM coil and start button SB mutually and between the zero line, is in series with contactor KM normally opened contact between said motor and the three-phase alternating-current supply.

The invention has the beneficial effects as follows: circuit is simple, and easy to connect with former circuit, cost is lower, and action is reliable relatively rapidly, the damage that can effectively avoid motor to cause because of phase shortage.

Description of drawings

Fig. 1 is that circuit of the present invention connects sketch map.

Embodiment

Operation principle:

Circuit is just often pressed start button SB, and contactor KM coil gets electric, and contactor KM normally opened contact is closed, the motor operate as normal.Circuit just often, neutral point voltage is zero.If a certain open circuit mutually, then neutral point voltage raises, and the series arm between neutral point and the zero line has voltage output; Capacitor C 1 charging this moment, while relay K A coil gets electric, and relay K A normally-closed contact breaks off; Thereby make the contactor KM coil losing electricity that is connected in series with relay K A normally-closed contact; And then the disconnection of contactor KM normally opened contact, motor quits work, and has played protective effect.

Capacitor C 1 is selected the oil-paper capacitor for use; Relay K A selects the DC24V miniature intermediate relay for use; Air circuit QF selects according to the capacity motor size; Contactor KM selects coil rating voltage AC220V according to the capacity motor size; Thermal relay FR selects according to the capacity motor size.

The foregoing description is said to be in order to specify this patent; Though describe through specific term in the literary composition; But can not limit the protection range of this patent with this; The personage who is familiar with this technical field can change or revise it after the spirit of understanding this patent and principle and reach equivalent purpose, and this equivalence change and modification all should be covered by the claim scope and define in the category.

Claims

1. a motor open-phase protection circuit comprises motor, the motor Y-connection on three-phase alternating-current supply, motor

And be in series with air circuit QF and thermal relay FR between the three-phase alternating-current supply; It is characterized in that: be in series with capacitor C 1 and relay K A coil between the neutral point of motor Y-connection and the zero line; Motor connects one in the three-phase firewire and is in series with relay K A normally-closed contact, contactor KM coil and start button SB mutually and between the zero line, is in series with contactor KM normally opened contact between said motor and the three-phase alternating-current supply.