Contactor main contact adhesion control protection circuit and method

Abstract

The invention discloses a control protection circuit and method for adhesion of a main contact of a contactor, and the circuit comprises a control protection circuit, a remote on-site start-stop loop, a thermal relay, and a circuit breaker. The control protection circuit comprises a main contactor, a standby contactor, an intermediate relay, a first power-on time-delay time relay, a second power-on time-delay time relay, a third power-on time-delay time relay and a scram button. When a main contact adhesion fault occurs in the main contactor, a power supply is cut off immediately, so that the safety of workers and equipment is better protected, and the property loss is avoided. Especially in the special working environment of hoisting equipment, the contact of the contactor is very easy to cause adhesion, and safety accidents are caused. The application of the invention can greatly reduce the accident rate.

Description

Technical Field

[0001] The invention relates to the field of electrical technology, and in particular to a control protection circuit and method for contactor main contact adhesion. Background Art

[0002] In the field of industrial production, contactors are widely used. They use electromagnetic force in conjunction with spring force to achieve the connection and disconnection of contacts, thereby avoiding manual operation to control the on and off of the circuit. This feature makes contactors very popular in today's electrical equipment, which tends to be automated and intelligent. Contactor control devices are widely used in various production scenarios such as large-scale factory equipment, intelligent electrical equipment, and power transmission and distribution systems. Although contactors are widely used, they themselves have some defects. Contact adhesion is a common fault of contactors.

[0003] For some frequently operated equipment, the main contacts, moving and static contacts of the AC contactor work under heavy load and high current for a long time, the contact material is seriously consumed or even consumed, the contact overtravel is reduced, the contact pressure becomes smaller or even cannot be overlapped, causing the contact resistance to increase; at the same time, the mechanism is stuck, which may also cause poor contact between the moving and static contacts. These may cause arcing between the moving and static contacts of the contactor. Since the fault occurs internally, it is often impossible to discover the fault in the first time, and the electrical equipment that should be powered off continues to run. If the power is not turned off in time, it may cause damage to the electrical equipment, and even cause fatal damage to the equipment and personnel, resulting in huge economic losses and safety accidents.

[0004] In order to eliminate the safety hazards caused by contactor sticking in the contactor control circuit, technical personnel in this field have been seeking effective control protection circuits and methods for the main contacts of the contactor, so that when a contactor contact sticking failure occurs, the equipment can be started and stopped normally, the power supply circuit can be cut off, and the safety hazards can be eliminated. Summary of the invention

[0005] The purpose of the present invention is to provide a control protection circuit and method for contactor main contact adhesion to solve accidents caused by AC contactor contact adhesion, better protect the safety of workers and avoid property loss.

[0006] In the first aspect, an embodiment of the present invention provides a control protection circuit for contactor main contact adhesion, comprising a control protection circuit, a remote local start-stop circuit, a thermal relay and a circuit breaker QF; the remote local start-stop circuit is used to remotely or locally control the on or off of the control power supply of the main contactor, thereby controlling the start and stop of the motor M; the thermal relay is used to overload the motor M; the circuit breaker QF is used to control the power supply of the circuit to be on or off, and to short-circuit the motor M; the special features thereof are:

[0007] The control protection circuit includes: a main contactor, a standby contactor, an intermediate relay, a first power-on delay type time relay, a second power-on delay type time relay, a third power-on delay type time relay and an emergency stop button EB;

[0008] The emergency stop button EB is used to disconnect the control power supply of the main contactor;

[0009] The main contactor is used to control the start or stop of the motor M under the control of the remote local start-stop circuit, and to control the emergency stop of the motor M under the control of the emergency stop button EB;

[0010] The intermediate relay is used to determine whether the main contactor is powered on, and when the main contactor is powered on, disconnect the power supply of the first power-on delay type time relay, the second power-on delay type time relay and the third power-on delay type time relay;

[0011] The first power-on delay type time relay, the second power-on delay type time relay and the third power-on delay type time relay are used to determine whether the main contacts of the main contactor are stuck. When the main contactor loses power, the power input end of the motor M is still powered on continuously, and the duration reaches a preset time, the control power supply of the standby contactor is disconnected;

[0012] The backup contactor is used to replace the main contactor to control the start or stop of the motor M when the main contact of the main contactor is stuck.

[0013] As a preferred solution, the live wires A, B and C of the power supply are connected to one end of the circuit breaker QF, the other end of the circuit breaker QF is connected to one end of the normally open main contact KM11 of the main contactor, the other end of the normally open main contact KM11 of the main contactor is connected to one end of the normally open main contact KM21 of the standby contactor, and the other end of the normally open main contact KM21 of the standby contactor is connected to the power input end of the motor M through the coil FR1 of the thermal relay.

[0014] Furthermore, the live phase C of the power supply is also connected to one end of the remote local start-stop circuit, the other end of the remote local start-stop circuit is connected to one end of the coil KM1 of the main contactor, the other end of the coil KM1 of the main contactor is connected to one end of the normally closed contact FR11 of the thermal relay, the other end of the normally closed contact FR11 of the thermal relay is connected to one end of the emergency stop button EB, and the other end of the emergency stop button EB is connected to the neutral phase N of the power supply.

[0015] As a preferred solution, the coil KA1 of the intermediate relay and the coil KM1 of the main contactor are connected in parallel between the other end of the remote local start / stop circuit and one end of the normally closed contact FR11 of the thermal relay.

[0016] Furthermore, the live phase C of the power supply is also connected to one end of the normally closed contact KT11 of the first power-on delay type time relay, the other end of the normally closed contact KT11 of the first power-on delay type time relay is connected to one end of the normally closed contact KT21 of the second power-on delay type time relay, the other end of the normally closed contact KT21 of the second power-on delay type time relay is connected to one end of the normally closed contact KT31 of the third power-on delay type time relay, the other end of the normally closed contact KT31 of the third power-on delay type time relay is connected to one end of the coil KM2 of the standby contactor, and the other end of the coil KM2 of the standby contactor is connected to the neutral phase N of the power supply.

[0017] Furthermore, the other end of the normally open main contact KM11 of the main contactor corresponds to the live power lines A, B and C phases, which are respectively connected to one end of the coil KT1 of the first power-on delay type time relay, the coil KT2 of the second power-on delay type time relay, and the coil KT3 of the third power-on delay type time relay; the other end of the coil KT1 of the first power-on delay type time relay, the coil KT2 of the second power-on delay type time relay, and the coil KT3 of the third power-on delay type time relay are connected to one end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay; and the other end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay is connected to the neutral line N phase of the power supply.

[0018] As a preferred solution, the normally closed auxiliary contact KM22 of the standby contactor is connected in series between two input terminals of the control device DCS, thereby generating an alarm signal to the control device DCS.

[0019] As a preferred solution, the live phase C of the power supply is also connected to one end of the coil KA2 of the power supply monitoring relay, and the other end of the coil KA2 of the power supply monitoring relay is connected to the neutral phase N of the power supply; the normally open contact KA21 of the power supply monitoring relay is connected to one end of the normally closed auxiliary contact KM22 of the standby contactor, and the other end of the normally open contact KA21 of the power supply monitoring relay is connected to the control device DCS; thereby, an alarm signal is generated to the control device DCS only when the live phase C of the power supply is energized.

[0020] In a second aspect, an embodiment of the present invention provides a control and protection method for contactor main contact adhesion, comprising the following steps:

[0021] Close the circuit breaker QF, select remote or local start through the remote local start-stop circuit, energize the coil KM1 of the main contactor, close the normally open main contact KM11 of the main contactor, and run the motor M;

[0022] When the remote or local stop is selected through the remote local start-stop circuit or the emergency stop button EB is pressed, the coil KM1 of the main contactor loses power, and the normally open main contact KM11 of the main contactor is disconnected, so that the motor M stops running;

[0023] When the normally open main contact KM11 of the main contactor is stuck, causing the motor M to be unable to stop running normally, at least one of the coil KT1 of the first power-on delay type time relay, the coil KT2 of the second power-on delay type time relay, and the coil KT3 of the third power-on delay type time relay is energized and starts timing. When the timing time reaches the preset duration, at least one of the normally closed contact KT11 of the first power-on delay type time relay or the normally closed contact KT21 of the second power-on delay type time relay or the normally closed contact KT31 of the third power-on delay type time relay is disconnected, the coil KM2 of the standby contactor loses power, and the normally open main contact KM21 of the standby contactor is disconnected, causing the motor M to stop running;

[0024] When the coil KM2 of the backup contactor loses power, the normally closed auxiliary contact KM22 of the backup contactor is disconnected, generating an alarm signal to the control device DCS;

[0025] When the normally open main contact KM11 of the main contactor becomes stuck, and the motor M needs to be operated again without replacing the main contactor, the emergency stop button EB is reset and the remote on-site start-stop circuit selects remote or local start, the coil KM1 of the main contactor is energized, the coil KA1 of the intermediate relay is energized, and the normally closed contact KA11 of the intermediate relay is disconnected, so that the coil KT1 of the first power-on delay time relay, the coil KT2 of the second power-on delay time relay, and the coil KT3 of the third power-on delay time relay are de-energized, the normally closed contact KT11 of the first power-on delay time relay, the normally closed contact KT21 of the second power-on delay time relay, and the normally closed contact KT31 of the third power-on delay time relay are closed, the coil KM2 of the standby contactor is energized, and the normally open main contact KM21 of the standby contactor is closed, so that the motor M is running.

[0026] As a preferred solution, the power-on delay time lengths of the coil KT1 of the first power-on delay time relay, the coil KT2 of the second power-on delay time relay, and the coil KT3 of the third power-on delay time relay are 0.1-0.5 seconds.

[0027] The present invention has the following beneficial effects:

[0028] (1) The present invention constructs a complete contactor main contact adhesion protection mechanism by introducing a backup contactor and a power-on delay time relay. When the main contactor contacts stick and the motor cannot stop normally, the power-on delay time relay can detect and cut off the power supply of the backup contactor in time, disconnecting the main contacts of the backup contactor, thereby stopping the operation of the motor, effectively avoiding safety hazards such as continuous operation of the motor and overload heating caused by contact adhesion, and significantly improving the reliability and safety of the motor operation. Furthermore, the normally closed auxiliary contacts of the backup contactor are connected in series with the control device to achieve a fault alarm.

[0029] (2) When the main contacts of the main contactor become stuck, the present invention allows the start and stop of the motor to be controlled by a backup contactor instead of the main contactor without replacing the main contactor, thereby improving the reliability and fault tolerance of the system, avoiding long downtime caused by waiting for the contactor to be replaced, and thus improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a schematic structural diagram of a specific embodiment of a control and protection circuit for contactor main contact adhesion of the present invention.

[0031] Figure 2 The present invention is a flow chart of a specific embodiment of a method for controlling and protecting adhesion of main contacts of a contactor.

[0032] Figure 3 The present invention is a schematic structural diagram of another specific embodiment of a control and protection circuit for contactor main contact adhesion of the present invention.

[0033] Explanation of the accompanying drawings: 1. Main contactor; 2. Backup contactor; 3. Intermediate relay; 4. First power-on delay type time relay; 5. Second power-on delay type time relay; 6. Third power-on delay type time relay; 7. Thermal relay; 8. Power supply monitoring relay; 9. Remote local start and stop circuit. DETAILED DESCRIPTION

[0034] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0035] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0036] Example 1

[0037] like Figure 1 The structural diagram of the control protection circuit of the contactor main contact adhesion of one embodiment of the present invention is shown in FIG. Figure 1 As shown, it includes a control protection circuit, a remote local start-stop circuit 9, a thermal relay 7 and a circuit breaker QF; the remote local start-stop circuit 9 is used to remotely or locally control the on or off of the control power supply of the main contactor 1, thereby controlling the start and stop of the motor M; the thermal relay 7 is used to overload the motor M; the circuit breaker QF is used to control the on or off of the power supply of the circuit and to short-circuit the motor M;

[0038] The control protection circuit includes: a main contactor 1, a standby contactor 2, an intermediate relay 3, a first power-on delay type time relay 4, a second power-on delay type time relay 5, a third power-on delay type time relay 6 and an emergency stop button EB;

[0039] Emergency stop button EB, used to disconnect the control power supply of main contactor 1;

[0040] The main contactor 1 is used to control the start or stop of the motor M under the control of the remote local start-stop circuit 9, and to control the emergency stop of the motor M under the control of the emergency stop button EB;

[0041] The intermediate relay 3 is used to determine whether the main contactor 1 is powered on. When the main contactor 1 is powered on, the power supply of the first power-on delay type time relay 4, the second power-on delay type time relay 5 and the third power-on delay type time relay 6 is disconnected;

[0042] The first power-on delay type time relay 4, the second power-on delay type time relay 5 and the third power-on delay type time relay 6 are used to determine whether the main contacts of the main contactor 1 are adhered. When the main contactor 1 loses power, the power input end of the motor M is still continuously powered, and the duration reaches a preset time, the control power supply of the standby contactor 2 is disconnected;

[0043] The backup contactor 2 is used to replace the main contactor 1 to control the start or stop of the motor M when the main contacts of the main contactor 1 are stuck.

[0044] Among them, the live wires A, B and C of the power supply are connected to one end of the circuit breaker QF, the other end of the circuit breaker QF is connected to one end of the normally open main contact KM11 of the main contactor 1, the other end of the normally open main contact KM11 of the main contactor 1 is connected to one end of the normally open main contact KM21 of the standby contactor 2, and the other end of the normally open main contact KM21 of the standby contactor 2 is connected to the power input end of the motor M through the coil FR1 of the thermal relay 7.

[0045] Among them, the live phase C of the power supply is also connected to one end of the remote local start-stop circuit 9, the other end of the remote local start-stop circuit 9 is connected to one end of the coil KM1 of the main contactor 1, the other end of the coil KM1 of the main contactor 1 is connected to one end of the normally closed contact FR11 of the thermal relay 7, the other end of the normally closed contact FR11 of the thermal relay 7 is connected to one end of the emergency stop button EB, and the other end of the emergency stop button EB is connected to the neutral phase N of the power supply.

[0046] Among them, the coil KA1 of the intermediate relay 3 and the coil KM1 of the main contactor 1 are connected in parallel between the other end of the remote local start-stop circuit 9 and one end of the normally closed contact FR11 of the thermal relay 7.

[0047] Among them, the live phase C of the power supply is also connected to one end of the normally closed contact KT11 of the first power-on delay type time relay 4, the other end of the normally closed contact KT11 of the first power-on delay type time relay 4 is connected to one end of the normally closed contact KT21 of the second power-on delay type time relay 5, the other end of the normally closed contact KT21 of the second power-on delay type time relay 5 is connected to one end of the normally closed contact KT31 of the third power-on delay type time relay 6, the other end of the normally closed contact KT31 of the third power-on delay type time relay 6 is connected to one end of the coil KM2 of the standby contactor 2, and the other end of the coil KM2 of the standby contactor 2 is connected to the neutral phase N of the power supply.

[0048] Among them, the power live wires A, B and C phases corresponding to the other end of the normally open main contact KM11 of the main contactor 1 are respectively connected to one end of the coil KT1 of the first power-on delay type time relay 4, the coil KT2 of the second power-on delay type time relay 5, and the coil KT3 of the third power-on delay type time relay 6; the other ends of the coil KT1 of the first power-on delay type time relay 4, the coil KT2 of the second power-on delay type time relay 5, and the coil KT3 of the third power-on delay type time relay 6 are connected to one end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay 3; and the other end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay 3 is connected to the power neutral wire N phase.

[0049] Among them, the normally closed auxiliary contact KM22 of the backup contactor 2 is connected in series between two input terminals of the control device DCS, thereby generating an alarm signal to the control device DCS.

[0050] Example 2

[0051] like Figure 2 FIG. 1 is a flow chart of a method for controlling and protecting contactor main contact adhesion according to an embodiment of the present invention, as shown in FIG. Figure 2 As shown, the method comprises the following steps:

[0052] Step 1, close the circuit breaker QF, select remote or local start through the remote local start-stop circuit 9, energize the coil KM1 of the main contactor 1, close the normally open main contact KM11 of the main contactor 1, and make the motor M run;

[0053] Step 2: When the remote or local stop or emergency stop button EB is pressed through the remote local start-stop circuit 9, the coil KM1 of the main contactor 1 loses power, and the normally open main contact KM11 of the main contactor 1 is disconnected, so that the motor M stops running;

[0054] Step 3, when the normally open main contact KM11 of the main contactor 1 is stuck, causing the motor M to be unable to stop running normally, at least one of the coil KT1 of the first power-on delay type time relay 4, the coil KT2 of the second power-on delay type time relay 5, and the coil KT3 of the third power-on delay type time relay 6 is energized and starts timing, and when the timing time reaches a preset duration, at least one of the normally closed contact KT11 of the first power-on delay type time relay 4 or the normally closed contact KT21 of the second power-on delay type time relay 5 or the normally closed contact KT31 of the third power-on delay type time relay 6 is disconnected, the coil KM2 of the standby contactor 2 loses power, and the normally open main contact KM21 of the standby contactor 2 is disconnected, so that the motor M stops running;

[0055] The power-on delay time length of the coil KT1 of the first power-on delay time relay 4, the coil KT2 of the second power-on delay time relay 5, and the coil KT3 of the third power-on delay time relay 6 is 0.1-0.5 seconds;

[0056] Step 4: When the coil KM2 of the standby contactor 2 loses power, the normally closed auxiliary contact KM22 of the standby contactor 2 is disconnected, and an alarm signal is generated to the control device DCS;

[0057] Step 5. When the normally open main contact KM11 of the main contactor 1 is stuck and the motor M needs to be run again without replacing the main contactor 1, the emergency stop button EB is reset and the remote on-site start-stop circuit 9 selects remote or local start, the coil KM1 of the main contactor 1 is energized, the coil KA1 of the intermediate relay 3 is energized, and the normally closed contact KA11 of the intermediate relay 3 is disconnected, so that the coil KT1 of the first power-on delay type time relay 4, the coil KT2 of the second power-on delay type time relay 5, and the coil KT3 of the third power-on delay type time relay 6 are de-energized, the normally closed contact KT11 of the first power-on delay type time relay 4, the normally closed contact KT21 of the second power-on delay type time relay 5, and the normally closed contact KT31 of the third power-on delay type time relay 6 are closed, the coil KM2 of the standby contactor 2 is energized, and the normally open main contact KM21 of the standby contactor 2 is closed, so that the motor M runs.

[0058] Example 3

[0059] like Figure 3 The structural diagram of the control protection circuit of the contactor main contact adhesion of one embodiment of the present invention is shown in FIG. Figure 3 As shown, the circuit is different from Example 1 only in that a power monitoring relay 8 is added to avoid the alarm signal of the normally open main contact KM11 of the main contactor 1 sticking due to power failure being transmitted to the control device DCS; the power live wire C phase is also connected to one end of the coil KA2 of the power monitoring relay 8, and the other end of the coil KA2 of the power monitoring relay 8 is connected to the power neutral wire N phase; the normally open contact KA21 of the power monitoring relay 8 is connected to one end of the normally closed auxiliary contact KM22 of the standby contactor 2, and the other end of the normally open contact KA21 of the power monitoring relay 8 is connected to the control device DCS; thereby, only when the power live wire C phase is energized, the normally open contact KA21 of the power monitoring relay 8 is closed, and an alarm signal is generated to the control device DCS.

[0060] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control and protection circuit for contactor main contact adhesion, comprising a control and protection circuit, a remote local start-stop circuit (9), a thermal relay (7) and a circuit breaker QF; the remote local start-stop circuit (9) is used to remotely or locally control the on or off of the control power supply of the main contactor (1), thereby controlling the start and stop of the motor M; the thermal relay (7) is used to perform overload protection on the motor M; the circuit breaker QF is used to control the on or off of the power supply of the circuit and perform short-circuit protection on the motor M; the characteristics are: The control protection circuit comprises: a main contactor (1), a standby contactor (2), an intermediate relay (3), a first power-on delay type time relay (4), a second power-on delay type time relay (5), a third power-on delay type time relay (6) and an emergency stop button EB; The emergency stop button EB is used to disconnect the control power supply of the main contactor (1); The main contactor (1) is used to control the start or stop of the motor M under the control of the remote local start-stop circuit (9), and to control the emergency stop of the motor M under the control of the emergency stop button EB; The intermediate relay (3) is used to determine whether the main contactor (1) is powered on, and when the main contactor (1) is powered on, disconnects the control power supplies of the first power-on delay type time relay (4), the second power-on delay type time relay (5) and the third power-on delay type time relay (6); The first power-on delay type time relay (4), the second power-on delay type time relay (5) and the third power-on delay type time relay (6) are used to determine whether the main contacts of the main contactor (1) are adhered, and when the main contactor (1) loses power and the power input end of the motor M continues to be energized, and when the duration reaches a preset time, the control power supply of the standby contactor (2) is disconnected; The backup contactor (2) is used to replace the main contactor (1) to control the start or stop of the motor M when the main contact of the main contactor (1) is adhered.

2. The control and protection circuit for contactor main contact adhesion according to claim 1, characterized in that: The live wires A, B and C of the power supply are connected to one end of the circuit breaker QF, the other end of the circuit breaker QF is connected to one end of the normally open main contact KM11 of the main contactor (1), the other end of the normally open main contact KM11 of the main contactor (1) is connected to one end of the normally open main contact KM21 of the standby contactor (2), and the other end of the normally open main contact KM21 of the standby contactor (2) is connected to the power input end of the motor M through the coil FR1 of the thermal relay (7).

3. The control and protection circuit for contactor main contact adhesion according to claim 2, characterized in that: The live phase C of the power supply is also connected to one end of the remote local start-stop circuit (9), the other end of the remote local start-stop circuit (9) is connected to one end of the coil KM1 of the main contactor (1), the other end of the coil KM1 of the main contactor (1) is connected to one end of the normally closed contact FR11 of the thermal relay (7), the other end of the normally closed contact FR11 of the thermal relay (7) is connected to one end of the emergency stop button EB, and the other end of the emergency stop button EB is connected to the neutral phase N of the power supply.

4. The control and protection circuit for contactor main contact adhesion according to claim 3, characterized in that: The coil KA1 of the intermediate relay (3) and the coil KM1 of the main contactor (1) are connected in parallel between the other end of the remote local start / stop circuit (9) and one end of the normally closed contact FR11 of the thermal relay (7).

5. The control and protection circuit for contactor main contact adhesion according to claim 4, characterized in that: The live phase C of the power supply is also connected to one end of the normally closed contact KT11 of the first power-on delay type time relay (4), the other end of the normally closed contact KT11 of the first power-on delay type time relay (4) is connected to one end of the normally closed contact KT21 of the second power-on delay type time relay (5), the other end of the normally closed contact KT21 of the second power-on delay type time relay (5) is connected to one end of the normally closed contact KT31 of the third power-on delay type time relay (6), the other end of the normally closed contact KT31 of the third power-on delay type time relay (6) is connected to one end of the coil KM2 of the standby contactor (2), and the other end of the coil KM2 of the standby contactor (2) is connected to the neutral phase N of the power supply.

6. The control and protection circuit for contactor main contact adhesion according to claim 5, characterized in that: The other end of the normally open main contact KM11 of the main contactor (1) corresponds to the live phases A, B and C of the power supply, respectively connected to one end of the coil KT1 of the first power-on delay type time relay (4), the coil KT2 of the second power-on delay type time relay (5) and the coil KT3 of the third power-on delay type time relay (6); the other end of the coil KT1 of the first power-on delay type time relay (4), the coil KT2 of the second power-on delay type time relay (5) and the coil KT3 of the third power-on delay type time relay (6) is connected to one end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay (3); the other end of the three-terminal terminal of the normally closed contact KA11 of the intermediate relay (3) is connected to the neutral phase N of the power supply.

7. The control and protection circuit for contactor main contact adhesion according to claim 5, characterized in that: The normally closed auxiliary contact KM22 of the backup contactor (2) is connected in series between two input terminals of the control device DCS, thereby generating an alarm signal to the control device DCS.

8. The control and protection circuit for contactor main contact adhesion according to claim 7, characterized in that: The live phase C of the power supply is also connected to one end of the coil KA2 of the power supply monitoring relay (8), and the other end of the coil KA2 of the power supply monitoring relay (8) is connected to the neutral phase N of the power supply; the normally open contact KA21 of the power supply monitoring relay (8) is connected to one end of the normally closed auxiliary contact KM22 of the standby contactor (2), and the other end of the normally open contact KA21 of the power supply monitoring relay (8) is connected to the control device DCS; thereby, an alarm signal is generated to the control device DCS only when the live phase C of the power supply is energized.

9. A control and protection method for contactor main contact adhesion, characterized in that: The steps include: The circuit breaker QF is closed, and remote or local start is selected through the remote local start-stop circuit (9), the coil KM1 of the main contactor (1) is energized, and the normally open main contact KM11 of the main contactor (1) is closed, so that the motor M runs; When remote or local stop is selected through the remote local start-stop circuit (9) or the emergency stop button EB is pressed, the coil KM1 of the main contactor (1) loses power, the normally open main contact KM11 of the main contactor (1) is disconnected, and the motor M stops running; When the normally open main contact KM11 of the main contactor (1) is stuck, causing the motor M to be unable to stop running normally, at least one of the coils KT1 of the first power-on delay type time relay (4), the coil KT2 of the second power-on delay type time relay (5), and the coil KT3 of the third power-on delay type time relay (6) is energized and starts timing. When the timing time reaches a preset time length, at least one of the normally closed contacts KT11 of the first power-on delay type time relay (4), the normally closed contact KT21 of the second power-on delay type time relay (5), and the normally closed contact KT31 of the third power-on delay type time relay (6) is disconnected, the coil KM2 of the standby contactor (2) loses power, and the normally open main contact KM21 of the standby contactor (2) is disconnected, causing the motor M to stop running; When the coil KM2 of the backup contactor (2) loses power, the normally closed auxiliary contact KM22 of the backup contactor (2) is disconnected, generating an alarm signal to the control device DCS; When the normally open main contact KM11 of the main contactor (1) is adhered, and the motor M needs to be operated again without replacing the main contactor (1), the emergency stop button EB is reset and the remote local start-stop circuit (9) selects remote or local start, the coil KM1 of the main contactor (1) is energized, the coil KA1 of the intermediate relay (3) is energized, the normally closed contact KA11 of the intermediate relay (3) is disconnected, and the coil KT1 of the first energized delay time relay (4) is energized. , the coil KT2 of the second power-on delay type time relay (5) and the coil KT3 of the third power-on delay type time relay (6) lose power, the normally closed contact KT11 of the first power-on delay type time relay (4), the normally closed contact KT21 of the second power-on delay type time relay (5) and the normally closed contact KT31 of the third power-on delay type time relay (6) are closed, the coil KM2 of the standby contactor (2) is energized, and the normally open main contact KM21 of the standby contactor (2) is closed, so that the motor M runs.

10. The control and protection method for contactor main contact adhesion according to claim 9, characterized in that: The power-on delay time lengths of the coil KT1 of the first power-on delay time relay (4), the coil KT2 of the second power-on delay time relay (5), and the coil KT3 of the third power-on delay time relay (6) are 0.1-0.5 seconds.

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