Self-holding circuit of motor protector

Abstract

The utility model relates to the technical field of motor protection, and discloses a self-hold circuit of a motor protector, which comprises a motor main loop and a motor protection loop, and the motor protection loop comprises a motor protector, an alternating current control loop, a contactor self-hold loop and a manual operation loop. The alternating current control loop comprises a main control loop and a self-holding loop, the main control loop comprises a tripping relay, a closing relay and a first normally open contact of the tripping relay, and the closing relay is connected in series with the normally open contact of the tripping relay and then connected in parallel with the tripping relay; the self-holding loop comprises a closing relay normally-open contact, a contactor normally-open contact and a tripping relay normally-closed contact. The closing relay normally-open contact and the contactor normally-open contact are connected in parallel and then are connected with the tripping relay normally-closed contact, a stop button and a contactor coil in series.

Description

TECHNICAL FIELD

[0001] The utility model relates to motor protection technical field especially relates to a motor motor protector self -holding circuit. BACKGROUND

[0002] With the continuous progress of science and technology, motor protector is more and more used in motor control circuit, especially in power plant, mining enterprises are particularly common. Motor protector can not only provide electrical control, background information communication, but also can analyze and calculate the collected current, voltage and other analog quantities to realize various protection functions (such as; speed protection, overcurrent protection, ground protection, low voltage protection, etc.).

[0003] Motor protector is a microcomputer type protection and control device, which is specially used for protecting motor equipment. The motor protector is a motor loop powered by a DC power supply. When the DC power supply fails and needs to be disconnected, the DC circuit breaker is used to find the fault point or when the DC power supply disappears, it will cause the problem of motor shutdown in the main loop. This kind of problem is more likely to occur when the service time of motor protector is continuously increased and the service life is continuously shortened. INVENTION CONTENTS

[0004] The technical problem to be solved by the utility model is to overcome the shortcomings of the prior art, and a motor motor protector self-holding circuit is provided to prevent motor mis-tripping caused by system fluctuation.

[0005] The technical scheme of the utility model is as follows: a motor motor protector self-holding circuit, comprising a motor main loop and a motor protection loop, the motor protection loop comprises a motor protector, an alternating current control loop, a contactor self-holding loop and a manual operation loop, the alternating current control loop comprises a main control loop and a self-holding loop, the main control loop comprises a tripping relay, a closing relay and a tripping relay first normally open contact, the closing relay and the tripping relay normally open contact are connected in series, and the tripping relay is connected in parallel, the self-holding loop comprises a closing relay normally open contact, a contactor normally open contact and a tripping relay normally closed contact, the closing relay normally open contact and the contactor normally open contact are connected in parallel, and the tripping relay normally closed contact, a stop button and a contactor coil are connected in series.

[0006] From the above scheme, it can be seen that the utility model prevents the motor mis-trip caused by system fluctuation, and can avoid the failure of the auxiliary contact of the contactor, has double protection, is used for realizing the self-holding of the motor motor protector after fault shutdown, and is helpful to the safe use of the motor motor protector.

[0007] The motor main loop comprises a circuit breaker, a contactor and a motor, the upper end of the circuit breaker is connected with three-phase alternating current, and the lower end is connected with the motor through the contactor.

[0008] The manual operation circuit comprises a circuit breaker normally open contact, a handle switch normally open contact, a change-over switch, a start button and a stop button, the circuit breaker normally open contact is connected in parallel with the handle switch normally open contact, the change-over switch is connected in series with the start button and then connected in parallel with a close relay normally open contact, and then connected in series with the stop button.

[0009] The power supply end of the motor protector is externally connected with a DC power supply bus. Thus, it can be seen that the motor protector adopts DC power supply. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a circuit principle diagram of a motor main circuit;

[0011] Figure 2 is a circuit principle diagram of a motor protection circuit. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model.

[0013] As shown in Figure 1 and Figure 2 The utility model discloses a motor motor protector self-holding circuit, including motor main circuit and motor protection circuit, the motor main circuit includes circuit breaker QF, contactor KM and motor M, the circuit breaker QF upper end connects three -phase alternating current, and the lower end is connected with motor M through contactor KM, the motor protection circuit includes motor protector K0, AC control circuit, contactor self-holding circuit and manual operation circuit, the power supply end of motor protector K0 is externally connected with DC power supply bus, the AC control circuit includes main control circuit and self-holding circuit, the main control circuit includes trip relay KA1, close relay KA2 and trip relay KA1 first normally open contact, the close relay KA2 is connected in parallel with trip relay KA1 normally open contact after being connected in series with trip relay KA1, the self-holding circuit includes close relay KA2 normally open contact, contactor KM normally open contact and trip relay KA1 normally closed contact, the close relay KA2 normally open contact and contactor KM normally open contact are connected in parallel after being connected in series with trip relay KA1 normally closed contact, stop button SB2 and contactor KM coil. In the embodiment, the contactor KM adopts three -phase alternating current contactor, and the close relay KA2 adopts DC relay.

[0014] The utility model also includes display lamp control circuit, display lamp control circuit includes closing relay KA2 normally open contact, red display lamp HR1 in series with closing relay KA2 normally open contact, trip relay KA1 normally open contact and green display lamp HG1 in series with trip relay KA1 normally open contact.

[0015] The utility model uses alternating current to start the contactor, then uses closing relay KA2 and trip relay KA1 as the on-off signal, the coil of the contactor KM continuously runs and is not influenced by the loss of direct current, only will be tripped when the alternating current is lost, can reduce the interference of the circuit.

[0016] When the system voltage fluctuates and the voltage is momentarily reduced (which will cause the contactor to be tripped), and then momentarily recovers, because of the self-holding function of the closing relay KA2, the contactor KM can continue to attract and the motor continues to run, and the anti-AC voltage interference ability is strong.

[0017] The manual operation circuit comprises a circuit breaker QF normally open contact, a handle switch SW normally open contact, a change-over switch SA, a start button SB1 and a stop button SB2, the circuit breaker QF normally open contact is connected in parallel with the handle switch SW normally open contact, the change-over switch SA is connected in series with the start button SB1 and then connected in parallel with the closing relay KA2 normally open contact, and then connected in series with the stop button SB2.

[0018] The working process of the utility model is as follows: when the system voltage fluctuates, the closing relay KA2 coil is electrified, the KA2 normally open contact is closed, the contactor KM coil is electrified, the KM normally open contact is closed, thereby realizing the self-holding of the closing relay KA2, the contactor KM coil is continuously electrified, the motor is started and runs, at this time, the KM normally open contact is closed, the KM normally closed contact is disconnected, the green indicator lamp HG1 is extinguished, and the red indicator lamp HR1 is lighted up.

[0019] When the trip control is performed, the trip relay KA1 coil is electrified, the KA1 normally closed contact is disconnected, the main contactor KM coil loses electricity, and the motor stops running, at this time, the KM normally open contact is disconnected, the KM normally closed contact is closed, the green indicator lamp HG1 is lighted up, and the red indicator lamp HR1 is extinguished.

[0020] The utility model discloses through the switching of change-over switch SA between on-site and remote, thereby realizes the tripping and closing control of on-site and remote respectively.

[0021] Finally, it should be emphasized that the above description is not intended to limit the utility model, for those skilled in the art, the utility model can have various changes and changes, any modification, equivalent replacement, improvement etc. that is made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A self-holding circuit for an electric motor protector, comprising a main motor circuit and a motor protection circuit, characterized in that: The motor protection circuit comprises a motor protector (K0), an AC control circuit, a contactor self-holding circuit and a manual operation circuit, the AC control circuit comprises a main control circuit and a self-holding circuit, the main control circuit comprises a trip relay (KA1), a close relay (KA2) and a first normally open contact of the trip relay (KA1), the close relay (KA2) is connected in parallel with the trip relay (KA1) after being connected in series with the normally open contact of the trip relay (KA1), the self-holding circuit comprises a normally open contact of the close relay (KA2), a normally open contact of a contactor (KM) and a normally closed contact of the trip relay (KA1), the normally open contact of the close relay (KA2) and the normally open contact of the contactor (KM) are connected in parallel and then connected in series with the normally closed contact of the trip relay (KA1), a stop button (SB2) and a coil of the contactor (KM).

2. A motor protector self-holding circuit according to claim 1, characterized in that: The motor main circuit comprises a circuit breaker (QF), a contactor (KM) and a motor (M), the upper end of the circuit breaker (QF) is connected with three-phase AC power, and the lower end of the circuit breaker (QF) is connected with the motor (M) through the contactor (KM).

3. A motor protector self-holding circuit according to claim 1, characterized in that: The manual operation circuit comprises a normally open contact of the circuit breaker (QF), a normally open contact of a handle switch (SW), a change-over switch (SA), a start button (SB1) and a stop button (SB2), the normally open contact of the circuit breaker (QF) is connected in parallel with the normally open contact of the handle switch (SW), the change-over switch (SA) is connected in series with the start button (SB1) and then connected in parallel with a normally open contact of the close relay (KA2), and then connected in series with the stop button (SB2).

4. A motor motor protector self-holding circuit according to claim 1, characterized in that: The power supply end of the motor protector (K0) is connected with a DC power bus.

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