Reasons for Overload of Valve Electric Actuator:
First, the power supply voltage is low and the required torque is not obtained, which makes the motor stop turning.
Secondly, the torque limiting mechanism is set incorrectly to make it larger than the stop torque, resulting in the continuous generation of excessive torque, so that the motor stops turning.
Third, intermittent use, resulting in heat accumulation, exceeding the allowable temperature rise of the motor;
Fourthly, for some reason, the circuit of the torque limiting mechanism fails, which makes the torque too large.
Fifth, the use of environmental temperature is too high, relatively reducing the thermal capacity of the motor.
In the past, fuses, overcurrent relays, thermal relays and thermostats were used to protect motors, but these methods have their own advantages and disadvantages. There is no absolutely reliable protection method for the variable load equipment of electric devices. Therefore, it is necessary to adopt various combinations, which can be summed up in two ways: one is to judge the increase or decrease of the input current of the motor; the other is to judge the enthusiastic condition of the motor itself. Either way, the time margin given by the thermal capacity of the motor should be taken into account.
Usually, the basic protection method of overload is:
1. The thermostat is used for the overload protection of the continuous operation or the point operation of the motor.
2. The thermal relay is used to protect the motor from blocking.
3. For short-circuit accidents, fuse or over-current relay is used.
Valve electric actuator is an indispensable device to realize valve programmable control, automatic control and remote control. Its motion process can be controlled by stroke, torque or axial thrust. Correct selection of valve electric device is very important to prevent overload (working torque is higher than control torque).