CN218940666U

CN218940666U - Control system for preventing phase-to-phase short circuit of three-phase motor during commutation

Info

Publication number: CN218940666U
Application number: CN202320030178.5U
Authority: CN
Inventors: 严宝强; 王维利; 王升; 张东; 王彦彪; 冯小龙; 闫冬生
Original assignee: Inner Mongolia Yitai Guanglian Coalification Co ltd; Inner Mongolia Zhongyu Taide Coal Co ltd; Ordos Zhongyu Taide Coal Co ltd
Current assignee: Inner Mongolia Yitai Guanglian Coalification Co ltd; Inner Mongolia Zhongyu Taide Coal Co ltd; Ordos Zhongyu Taide Coal Co ltd
Priority date: 2023-01-05
Filing date: 2023-01-05
Publication date: 2023-04-28
Anticipated expiration: 2033-01-05

Abstract

The utility model discloses a control system for preventing a three-phase motor from generating interphase short circuit during reversing, wherein an intermediate relay is connected in series between an A phase and a C phase between a thermal relay of a main loop and a normally open contact of an alternating current contactor; two groups of normally-closed contacts of an intermediate relay are connected in the control loop, wherein one group of normally-closed contacts are connected in series with a forward rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the forward rotation contactor, and the other group of normally-closed contacts are connected in series with a reverse rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the reverse rotation contactor. The advantages are that: the system has strong stability and high safety; when an arc exists between the phases, the normally closed contact of the intermediate relay is in an off state, so that the system cannot start the motor to work even if a reverse operation button is pressed, the phase short circuit is avoided, and the failure rate and the operation cost of the system operation are reduced.

Description

Control system for preventing phase-to-phase short circuit of three-phase motor during commutation

Technical field:

the utility model relates to the field of motor control, in particular to a control system for preventing phase-to-phase short circuit of a three-phase motor during commutation.

The background technology is as follows:

the equipment such as a belt conveyor, a scraper and the like used in a coal washery always needs reversing operation in operation, the reversing operation is realized by controlling the motor to rotate forwards or reversely, a specific control principle and a control process are shown in fig. 1 and 2, a normally open contact of a forward-rotating contactor KM1 and a normally open contact of a reverse-rotating contactor KM2 are respectively connected in a motor main loop, the control of the forward-rotating switching of the motor is realized through the control loop, in the control loop, the motor forward-rotating reverse-rotating circuit has the same structure, a forward-rotating your loop is taken as an example, a motor stop button SB1, a motor forward-rotating starting button SB2 and a forward-rotating contactor KM1 form a closed loop, the normally open contact of the forward-rotating contactor KM1 is connected in parallel with two ends of the motor forward-rotating starting button SB2, when the motor forward-rotating is required to be controlled, the coil and the contact of the forward-rotating contactor KM1 are powered on, when the motor is required to be controlled to rotate reversely, the stop button SB1 is firstly pressed, the motor reverse-rotating starting button SB3 is pressed, the coil and the contact of the reverse-rotating contactor KM2 is powered on, and the motor is powered on to rotate reversely.

In order to ensure the safe switching of the motor and prevent misoperation in the switching process, as shown in fig. 1, a button interlocking and contact interlocking design is added in a control circuit, namely a normally closed contact of a motor reverse button SB3 and a group of normally closed contacts of a reverse contactor KM2 are connected in series in a motor forward loop. When the motor reverse rotation start button SB3 is directly pressed during the forward rotation of the motor, the normally closed contact of the reverse rotation contactor KM2 is opened, and the motor stops the forward rotation. However, when the motor is controlled to be frequently switched in forward and reverse directions, serious electric arcs are inevitably generated between contacts of the contactor, if the motor is started to run reversely when the electric arcs are not completely extinguished, interphase short circuit can be caused, and the motor is burnt out seriously.

The utility model comprises the following steps:

the utility model aims to provide a control system capable of monitoring an arc state when a motor commutates and preventing interphase short circuit, wherein the control system can only be started in an arc extinguishing state.

The utility model is implemented by the following technical scheme: a control system for preventing phase-to-phase short circuit of a three-phase motor during commutation comprises a main loop and a control loop; an intermediate relay is connected in series between an A phase and a C phase between the thermal relay of the main loop and a normally open contact of the alternating current contactor; two groups of normally-closed contacts of the intermediate relay are connected in the control loop, wherein one group of normally-closed contacts are connected in series with a forward rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the forward rotation contactor, and the other group of normally-closed contacts are connected in series with a reverse rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the reverse rotation contactor.

Preferably, the electric arc indicator lamp is included, and the electric arc indicator lamp, a normally open contact of the intermediate relay and a stop button of the motor form a closed loop.

Preferably, the motor further comprises a safety indicator lamp, wherein the safety indicator lamp, the normally closed contact of the intermediate relay and the stop button of the motor form a closed loop.

The utility model has the advantages that: the circuit has simple structure, strong system stability and high safety; an intermediate relay is connected between the phase A and the phase C of the three-phase line to monitor the state of the electric arc, and when the electric arc exists between the phase A and the phase C, an electric arc indicator lamp is on to prompt that the reversing operation can not be performed; when an arc exists between the two phases, the normally closed contact of the intermediate relay is in an off state, so that the system cannot start the motor to work even if the reverse operation button is pressed, the phase short circuit is avoided, and the failure rate and the operation cost of the system operation are reduced.

Description of the drawings:

in order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a diagram of a motor forward and reverse rotation control circuit in the prior art.

Fig. 2 is a main circuit diagram of a motor according to the prior art.

Fig. 3 is a control circuit diagram of embodiment 1 of the present utility model.

Fig. 4 is a main circuit connection diagram of embodiment 1.

The specific embodiment is as follows:

the following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Example 1:

1-2, a control system for preventing a three-phase motor from generating interphase short circuit during commutation comprises a main loop and a control loop, wherein an intermediate relay KA is connected between an A phase and a C phase of the main loop to monitor interphase electric arcs, and the intermediate relay KA is arranged between a thermal relay FR1 and a normally open contact of an alternating current contactor as shown in FIG. 2. When an arc exists between the two phases, the coil of the intermediate relay KA is electrified, and the contacts in the control loop perform corresponding actions.

As shown in fig. 1, two groups of normally closed contacts of an intermediate relay KA are connected in the control loop, wherein one group of normally closed contacts are connected in series with a forward rotation starting button SB2 of the motor and then connected in parallel with two ends of a normally open contact of a forward rotation contactor KM1, and the other group of normally closed contacts are connected in series with a reverse rotation starting button SB3 of the motor and then connected in parallel with two ends of a normally open contact of a reverse rotation contactor KM 2.

In order to visually display the state of an arc between phases, an arc indicator lamp 1 and a safety indicator lamp 2 are connected for indication, wherein the arc indicator lamp 1, a normally open contact of an intermediate relay KA and a stop button group SB1 of a motor form a closed loop, and when the arc exists between the phases, the arc indicator lamp 1 is on to prompt that the reversing operation can not be performed; the safety indicator lamp 2 forms a closed loop with the normally closed contact of the intermediate relay KA and the stop button of the motor, and when the phase is completely extinguished, the safety indicator lamp 2 is on to prompt that reversing operation can be performed.

Description of use: when the motor M1 needs to be controlled to rotate positively, a motor forward rotation starting button SB1 is pressed, at the moment, a coil and a normally open contact of a forward rotation contactor KM1 are electrified, the forward rotation contactor KM forms a self-locking loop, the motor KM starts to rotate positively, meanwhile, a coil of an intermediate relay KA is electrified, an arc indication lamp 1 is on, and the fact that reversing operation cannot be performed is prompted. When the reversing is needed, firstly, the stop button SB1 is pressed down, if no arc exists between the phases at this time, the coil of the intermediate relay KA is powered off, the normally closed contact of the intermediate relay is closed, the safety indicator lamp 2 is on, the reversing is prompted to be possible, at this time, the motor reverse starting SB3 is pressed down, and the motor M1 starts to reverse. If the stop button is pressed down, the electric arc still exists between the phases, the electric arc indicator lamp 1 continues to lighten after being extinguished briefly, the direction is not allowed, meanwhile, the normally closed contact of the intermediate relay KA is in a disconnection state, the motor M1 cannot be started to reverse by pressing down the motor reversing button SB3, and the direction changing operation can be performed only after the electric arc between the phases is completely extinguished.

The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.

Claims

1. A control system for preventing phase-to-phase short circuit of a three-phase motor during commutation comprises a main loop and a control loop; it is characterized in that the method comprises the steps of,

an intermediate relay is connected in series between an A phase and a C phase between the thermal relay of the main loop and a normally open contact of the alternating current contactor;

two groups of normally-closed contacts of the intermediate relay are connected in the control loop, wherein one group of normally-closed contacts are connected in series with a forward rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the forward rotation contactor, and the other group of normally-closed contacts are connected in series with a reverse rotation starting button of the motor and then connected in parallel with two ends of a normally-open contact of the reverse rotation contactor.

2. A control system for preventing phase-to-phase short circuit of a three-phase motor during commutation according to claim 1, comprising an arc indicator lamp, said arc indicator lamp forming a closed loop with a normally open contact of said intermediate relay and a stop button of said motor.

3. A control system for preventing phase-to-phase short circuit of a three-phase motor according to any one of claims 1 or 2, further comprising a safety indicator lamp, said safety indicator lamp forming a closed loop with a normally closed contact of said intermediate relay and a stop button of said motor.