Electric valves are driven by electricity, and their movement process can be controlled by the magnitude of stroke, torque, or axial thrust. The working characteristics and utilization rate of valve electric devices depend on the type of valve, the working specifications of the device, and the position of the valve on the pipeline or equipment. Therefore, mastering the correct selection of valve electric devices and considering the prevention of overload (working torque higher than control torque) has become a crucial step.

In the past, the methods for protecting motors included using fuses, overcurrent relays, thermal relays, thermostats, etc. However, each of these methods has its own advantages and disadvantages. For electric devices with variable loads, there is no absolutely reliable protection method. Therefore, it is necessary to adopt a combination of various methods. However, due to the different load conditions of each electric device, it is difficult to propose a unified solution. But in most cases, commonalities can also be found. The overload protection methods adopted can be summarized into two types:

01 Determine the increase or decrease of motor input current.

02 Determine the heating of the motor itself.

Both of the above methods should consider the time margin given by the motor's thermal capacity. It is difficult to make it consistent with the thermal capacity characteristics of the motor in a single way. So we should choose a reliable method of action based on the cause of overload - the combination and composite method, to achieve comprehensive overload protection.

Mining series

Basic protection methods for overload:

01 Thermostat is used for overload protection of continuous operation or jog operation of the motor;

02. Thermal relay is used for motor stalling protection;

03 Use fuses or overcurrent relays for short-circuit accidents;