Open-phase protector for three-phase motor

Abstract

The utility model provides an open-phase protector for a three-phase motor, and relates to the technical field of three-phase motors, the open-phase protector comprises a power supply, a motor, a power supply circuit and a control circuit, the power supply circuit comprises a first power supply line, a second power supply line, a third power supply line and a power supply contactor, the power supply contactor controls the first power supply line, the second power supply line and the third power supply line to be synchronously disconnected and connected, and the first power supply line, the second power supply line and the third power supply line are sequentially arranged between the power supply and the motor; the control circuit comprises a main control branch and a relay, and the relay is arranged on the main control branch; the main control branch is arranged between the first power supply line and the second power supply line, the two ends of the main control branch are communicated with the first power supply line and the second power supply line respectively, and the power supply contactor can be disconnected due to phase loss caused by open circuit of the first power supply line or the second power supply line and no current passes through the main control relay; the first power supply line, the second power supply line and the third power supply line are disconnected synchronously, the motor stops running, and a coil of the motor is protected from being burnt out.

Description

Technical Field

[0001] This application belongs to the field of three-phase motor technology, and more specifically, relates to a phase loss protector for a three-phase motor. Background Technology

[0002] The number of three-phase asynchronous motors that burn out due to power outages is staggering. In most cases, this is caused by poor contact in low-voltage circuit breakers or disconnecting switches: AC contactors burn out and cannot reliably make contact; fuses are used for too long and the fuse wires are oxidized and corroded, and they burn out due to the impact of starting current, etc.

[0003] The existing three-phase asynchronous motors have the following main drawbacks: In three-phase motor electrical equipment, the motor often experiences a phase loss phenomenon due to poor contact of the contacts or loose wiring terminals, which leads to the burnout of the motor stator coil; when the motor runs for a long time and the temperature is too high, it will damage the internal coils of the motor and its power supply circuit. Summary of the Invention

[0004] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a phase loss protector for a three-phase motor. The technical solution adopted in this application is as follows:

[0005] A phase loss protector for a three-phase motor includes a power supply, a motor, a power supply circuit, and a control circuit. The power supply circuit includes a first power supply line, a second power supply line, a third power supply line, and a power supply contactor. The power supply contactor controls the synchronous disconnection and connection of the first, second, and third power supply lines. The first, second, and third power supply lines are sequentially arranged between the power supply and the motor. The control circuit includes a main control branch and a main control relay. The main control relay is located on the main control branch. The main control branch is located between the first and second power supply lines, and its two ends are respectively connected to the first and second power supply lines. The main control relay is used to control the power supply contactor.

[0006] Preferably, the control circuit further includes a monitoring contactor, which is also located on the main control branch; the control circuit also includes a monitoring branch and a monitoring relay, with the monitoring relay located on the monitoring branch; the monitoring branch is located between the second power supply line and the third power supply line, with both ends of the monitoring branch connected to the second power supply line and the third power supply line respectively, and the monitoring relay is used to control the monitoring contactor.

[0007] Preferably, the main control branch also includes a monitoring contactor, which is also located on the main control branch; the control circuit also includes a monitoring branch and a monitoring relay, with the monitoring relay located on the monitoring branch; the monitoring branch is located between the first power supply line and the third power supply line, with both ends of the monitoring branch connected to the first power supply line and the third power supply line respectively, and the monitoring relay is used to control the monitoring contactor.

[0008] Preferably, the control circuit further includes a start button, which is used to close the power supply contactor.

[0009] Preferably, the control circuit further includes a stop button, which is used to disconnect the power supply contactor.

[0010] Preferably, the control circuit further includes a temperature control contactor, which is located on the main control branch; the power supply circuit further includes a temperature control relay, which is used to control the on / off state of the temperature control contactor; the first power supply line, the second power supply line and the third power supply line are all connected to the temperature control relay.

[0011] Preferably, the power supply circuit further includes a three-phase circuit breaker, which controls whether the first power supply line, the second power supply line, and the third power supply line are disconnected synchronously.

[0012] Preferably, the three-phase circuit breaker is a type D circuit breaker.

[0013] The advantages of this utility model are as follows:

[0014] The power supply circuit supplies power to the motor, while the control circuit controls and protects the motor. The main control relay controls the power supply contactor. When current flows through the main control relay, it can drive the power supply contactor to close, and the motor will run normally. When no current flows through the main control relay, the power supply contactor will open, and the first, second, and third power supply lines will open simultaneously, stopping the motor and protecting the motor coils from burning out. The main control relay is located on the main control branch, which is located between the first and second power supply lines. If a phase is lost due to an open circuit in either the first or second power supply line, the power supply contactor will open to ensure the safe operation of the motor.

[0015] If no current flows through the monitoring branch, the monitoring contactor will disconnect. If the main control branch experiences an open circuit, the power supply contactor will disconnect, and the motor will stop running. The monitoring branch is located between the second and third power supply lines. If a phase loss occurs due to an open circuit in either the second or third power supply line, the power supply contactor will disconnect to ensure the safe operation of the motor. In this case, if a phase loss occurs due to an open circuit in any one or more of the first, second, and third power supply lines, the power supply contactor will disconnect to ensure the safe operation of the motor. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1This is a schematic diagram of the first embodiment of a phase loss protector for a three-phase motor;

[0018] Figure 2 This is a schematic diagram of the second implementation of a phase loss protector for a three-phase motor.

[0019] Explanation of symbols in the diagram:

[0020] 1 is the power supply;

[0021] 2 is the motor;

[0022] 3 is the power supply circuit, 31 is the first power supply line, 32 is the second power supply line, 33 is the third power supply line, 34 is the power supply contactor, 35 is the temperature control relay, and 36 is the three-phase circuit breaker.

[0023] 4 is the control circuit, 41 is the main control branch, 42 is the main control relay, 43 is the monitoring contactor, 44 is the monitoring branch, 45 is the monitoring relay, 46 is the start button, 47 is the stop button, and 48 is the temperature control contactor. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0025] The phase loss protector for a three-phase motor provided in the embodiments of this application will now be described.

[0026] Example

[0027] like Figure 1 As shown, a phase loss protector for a three-phase motor includes a power supply 1, a motor 2, a power supply circuit 3, and a control circuit 4. The power supply circuit 3 includes a first power supply line 31, a second power supply line 32, a third power supply line 33, and a power supply contactor 34. The power supply contactor 34 controls the synchronous disconnection and connection of the first power supply line 31, the second power supply line 32, and the third power supply line 33. The first power supply line 31, the second power supply line 32, and the third power supply line 33 are sequentially arranged between the power supply 1 and the motor 2. The control circuit 4 includes a main control branch 41 and a main control relay 42. The main control relay 42 is located on the main control branch 41. The main control branch 41 is located between the first power supply line 31 and the second power supply line 32, with both ends connected to the first power supply line 31 and the second power supply line 32, respectively. The main control relay 42 controls the power supply contactor 34. The power supply 1 uses a three-phase power supply, with the first power supply line 31, the second power supply line 32, and the third power supply line 33 each connected to one phase of the power supply 1.

[0028] Power supply 1 supplies power to motor 2 through power supply circuit 3. Control circuit 4 is used to control and protect motor 2. Main control relay 42 is used to control power supply contactor 34. When current flows through main control relay 42, it can drive power supply contactor 34 to close, and motor 2 will run normally. When no current flows through main control relay 42, power supply contactor 34 will open, and the first power supply line 31, the second power supply line 32, and the third power supply line 33 will open simultaneously, motor 2 will stop running, and the coil of motor 2 will be protected from being burned out. Main control relay 42 is located on main control branch 41, which is located between the first power supply line 31 and the second power supply line 32. If a phase is lost due to an open circuit in the first power supply line 31 or the second power supply line 32, power supply contactor 34 will open to ensure the safe use of motor 2.

[0029] The control circuit 4 also includes a monitoring contactor 43, which is also located on the main control branch 41; the control circuit 4 also includes a monitoring branch 44 and a monitoring relay 45, which is located on the monitoring branch 44; the monitoring branch 44 is located between the second power supply line 32 and the third power supply line 33, and the two ends of the monitoring branch 44 are connected to the second power supply line 32 and the third power supply line 33 respectively; the monitoring relay 45 is used to control the monitoring contactor 43.

[0030] The monitoring relay 45 is located on the monitoring branch 44. When current flows through the monitoring branch 44, it will cause the monitoring contactor 43 to close; when no current flows through the monitoring branch 44, it will cause the monitoring contactor 43 to open, resulting in an open circuit in the main control branch 41. This will cause the power supply contactor 34 to disconnect, stopping the motor 2. The monitoring branch 44 is located between the second power supply line 32 and the third power supply line 33. If a phase loss occurs due to an open circuit in either the second or third power supply line 32, the power supply contactor 34 will disconnect, ensuring the safe operation of the motor 2. Similarly, if a phase loss occurs due to an open circuit in any one or more of the first, second, or third power supply lines 31, the power supply contactor 34 will disconnect, ensuring the safe operation of the motor 2.

[0031] like Figure 2 As shown, the monitoring branch 44 can also be located between the first power supply line 31 and the third power supply line 33. The two ends of the monitoring branch 44 are connected to the first power supply line 31 and the third power supply line 33 respectively. The monitoring relay 44 is used to control the monitoring contactor 43.

[0032] The control circuit 4 also includes a start button 46, which is used to close the power supply contactor 34 to start the motor 2 for easy operation.

[0033] The control circuit 4 also includes a stop button 47, which is used to disconnect the power supply contactor 34 and turn off the motor 2 for easy operation.

[0034] The control circuit also includes a temperature control contactor 48, which is located on the main control branch 41. When the temperature of the first power supply line 31, the second power supply line 32, or the third power supply line 33 is too high, the temperature control contactor 48 will disconnect, and no current will flow through the main control branch 41 and the main control relay 42. The power supply contactor 34 will then disconnect, protecting the motor 2 and its wiring. The power supply circuit 3 also includes a temperature control relay 35, which is used to control the on / off state of the temperature control contactor 48. The first power supply line 31, the second power supply line 32, and the third power supply line 33 are all connected to the temperature control relay 35.

[0035] The power supply circuit 3 also includes a three-phase circuit breaker 36, which controls whether the first power supply line 31, the second power supply line 32 and the third power supply line 33 are disconnected synchronously.

[0036] The three-phase circuit breaker 36 adopts a type D circuit breaker, which can avoid the effect of the large current when the motor 2 starts and prevent tripping when the motor 2 is opened.

[0037] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A phase loss protector for a three-phase motor, comprising a power supply, a motor, a power supply circuit, and a control circuit, characterized in that: The power supply circuit includes a first power supply line, a second power supply line, a third power supply line, and a power supply contactor. The power supply contactor controls the first, second, and third power supply lines to simultaneously disconnect and connect. The first, second, and third power supply lines are sequentially arranged between the power source and the motor. The control circuit includes a main control branch and a main control relay. The main control relay is located on the main control branch. The main control branch is located between the first and second power supply lines, and its two ends are respectively connected to the first and second power supply lines. The main control relay is used to control the power supply contactor.

2. The phase loss protector for a three-phase motor according to claim 1, characterized in that: The control circuit also includes a monitoring contactor, which is also located on the main control branch; the control circuit also includes a monitoring branch and a monitoring relay, which is located on the monitoring branch; the monitoring branch is located between the second power supply line and the third power supply line, and both ends of the monitoring branch are connected to the second power supply line and the third power supply line respectively, and the monitoring relay is used to control the monitoring contactor.

3. The phase loss protector for a three-phase motor according to claim 1, characterized in that: The main control branch also includes a monitoring contactor, which is also located on the main control branch; the control circuit also includes a monitoring branch and a monitoring relay, which is located on the monitoring branch; the monitoring branch is located between the first power supply line and the third power supply line, and both ends of the monitoring branch are connected to the first power supply line and the third power supply line respectively, and the monitoring relay is used to control the monitoring contactor.

4. The phase loss protector for a three-phase motor according to any one of claims 1 to 3, characterized in that: The control circuit also includes a start button, which is used to close the power supply contactor.

5. The phase loss protector for a three-phase motor according to claim 4, characterized in that: The control circuit also includes a stop button, which is used to disconnect the power supply contactor.

6. The phase loss protector for a three-phase motor according to any one of claims 1 to 3, characterized in that: The control circuit further includes a temperature control contactor, which is located on the main control branch; the power supply circuit further includes a temperature control relay, which is used to control the on / off state of the temperature control contactor; the first power supply line, the second power supply line, and the third power supply line are all connected to the temperature control relay.

7. The phase loss protector for a three-phase motor according to any one of claims 1 to 3, characterized in that: The power supply circuit also includes a three-phase circuit breaker, which controls whether the first power supply line, the second power supply line and the third power supply line are disconnected synchronously.

8. The phase loss protector for a three-phase motor according to claim 7, characterized in that: The three-phase circuit breaker is a type D circuit breaker.

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