Electric valve overload protection method


The electric valve is one of the devices that operate the valve and connect with the valve. The device is driven by electricity, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization of the valve electric device depend on the type of valve, the working specification of the device and the position of the valve on the pipeline or equipment. Therefore, mastering the correct selection of the valve electric device; considering preventing the occurrence of overload (the working torque is higher than the control torque) has become a crucial part.
In the past, the way to protect the motor was to use fuses, overcurrent relays, thermal relays, thermostats, etc., but these methods also have their own advantages and disadvantages. For equipment with variable loads such as electric devices, there is no absolutely reliable protection method. . Therefore, a combination of various methods must be adopted. However, due to the different load conditions of each electric device, it is difficult to propose a unified method. But generalizing most of the cases, we can also find common ground.

The overload protection methods adopted are summarized into two types

1. Judge the increase or decrease of the motor input current;
2. Judge the heat of the motor itself.
The above two methods, no matter which kind, should consider the time margin given by the thermal capacity of the motor. It is difficult to match the thermal capacity characteristics of the motor in a single way. Therefore, a method that can reliably act according to the cause of the overload should be selected-combined composite method to achieve a comprehensive overload protection effect.
The motor of the Rotork electric device has a thermostat embedded in the winding that is consistent with the insulation level of the motor. When the rated temperature is reached, the motor control circuit will be cut off. The thermostat itself has a small heat capacity, and its time-limiting characteristics are determined by the heat capacity characteristics of the motor, so this is a reliable method.

Basic protection methods for overload

1. A thermostat is used for overload protection of motor continuous operation or jog operation;
2. The protection of the motor locked rotor adopts thermal relay;
3. Use fuses or overcurrent relays for short-circuit accidents.
The correct selection of the valve electric device and the prevention of overload are closely related and should be paid attention to.
The electric valve is one of the devices that operate the valve and connect with the valve. The device is driven by electricity, and its movement process can be controlled by stroke, torque or axial thrust. Because the working characteristics and utilization of the valve electric device depend on the type of valve, the working specification of the device and the position of the valve on the pipeline or equipment. Therefore, mastering the correct selection of the valve electric device; considering preventing the occurrence of overload (the working torque is higher than the control torque) has become a crucial part.
In the past, the way to protect the motor was to use fuses, overcurrent relays, thermal relays, thermostats, etc., but these methods also have their own advantages and disadvantages. For equipment with variable loads such as electric devices, there is no absolutely reliable protection method. . Therefore, a combination of various methods must be adopted. However, due to the different load conditions of each electric device, it is difficult to propose a unified method. But generalizing most of the cases, we can also find common ground.

The overload protection methods adopted are summarized into two types

1. Judge the increase or decrease of the motor input current;
2. Judge the heat of the motor itself.
The above two methods, no matter which kind, should consider the time margin given by the thermal capacity of the motor. It is difficult to match the thermal capacity characteristics of the motor in a single way. Therefore, a method that can reliably act according to the cause of the overload should be selected-combined composite method to achieve a comprehensive overload protection effect.
The motor of the Rotork electric device has a thermostat embedded in the winding that is consistent with the insulation level of the motor. When the rated temperature is reached, the motor control circuit will be cut off. The thermostat itself has a small heat capacity, and its time-limiting characteristics are determined by the heat capacity characteristics of the motor, so this is a reliable method.

Basic protection methods for overload

1. A thermostat is used for overload protection of motor continuous operation or jog operation;
2. The protection of the motor locked rotor adopts thermal relay;
3. Use fuses or overcurrent relays for short-circuit accidents.
The correct selection of the valve electric device and the prevention of overload are closely related and should be paid attention to.

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