Electric Actuator Controls: Operation, Failures, and Troubleshooting

What is An Actuator?

A drive device that can provide linear or rotary motion, using a certain amount of drive energy and working under a certain control signal. Actuators use liquid, gas, electricity or other energy, and convert it into drive action through electric motors, cylinders or other devices.

 

What Are the 2 Most Common Actuators?

Electric actuators are generally divided into two main types based on their operation:

 

• Part-Turn Electric Actuators

These actuators are typically used for valves requiring partial rotation, such as ball valves and butterfly valves. They perform precise rotational movements for quick control.

 

• Multi-Turn Electric Actuators

These are designed for valves requiring multiple turns, such as gate valves. Multi-turn actuators provide the force needed to turn these valves many times around for precise flow regulation.

 

Electric Actuator Valve Operations

1. Opening the Valve

Upon receiving the opening signal, the electric actuator’s motor rotates in the correct direction. This action moves the valve stem upward or in the opening direction, allowing the valve to gradually open. The actuator will stop when it reaches the fully open position, or the set flow requirement is met.

 

2. Closing the Valve

When a closing signal is received, the motor rotates in the opposite direction, moving the valve stem downward or in the closing direction. The valve gradually closes, blocking the flow of the medium. The actuator will confirm full closure through a limit device.

 

3. Stopping the Valve

If a stop signal is received during opening or closing, the actuator motor halts immediately, holding the valve in its current position. This is typically done when the preset valve opening is achieved or when an abnormal situation requires stopping the action.

 

Troubleshooting Common Electric Actuator Failures

1. Valve Opening Failure

Causes: Power supply issues (e.g., phase loss, low voltage), motor winding damage, control circuit failure, or mechanical problems such as stuck transmission parts.

Solution: Check the power supply and verify that the motor is receiving the proper signal.

 

2. Valve Closing Failure

Causes: Issues like motor failure, signal transmission problems, valve stem deformation, or damaged seals.

Solution: Inspect for mechanical jams or electrical faults, and replace any worn components.

 

3. Stop Failure

Causes: Faulty relays in the control circuit or a malfunctioning limit switch that prevents the actuator from halting.

Solution: Inspect and replace the faulty relay or limit switch.

 

 

Why Electric Actuators Excel Over Pneumatic Actuators？

Electric actuators are known for their superior anti-deviation ability. Electric actuators maintain consistent output thrust or torque, making them more accurate than pneumatic actuators. This results in higher control precision, as electric actuators can overcome unbalanced forces from the medium.

Additionally, when equipped with a servo amplifier, the valve position state (e.g., hold, fully open, or fully closed) can be easily adjusted, even during faults. Unlike pneumatic actuators, which require a combined protection system to maintain valve position, electric actuators remain stable in the event of failure.

 

FAQs

Q: The regulating module of the electric actuator does not respond

A: First try to power off and restart. If power off and restart does not work, remove the four screws on the side of the module to see if the pin header of the regulating module has been squeezed and damaged. If it is broken, the module is useless and needs to be resent.

Q: Why does the electric actuator get hot?

A: The torque is too large

Q: What will happen to the actuator if the micro switch inside the electric actuator fails?

A: Two situations: 1. The actuator does not move 2. The actuator keeps opening or closing and will not stop

Q: The electric actuator is leaking. How to solve it?

A: Check whether the actuator is operating normally and whether there is water inside the actuator (inside)? If it can operate normally and there is no internal leakage, it should be a valve leak or a valve connection pipe leak.

Q: Electric actuator makes noise during operation. What causes it?

A: If the noise is loud, it should be that some bearings are loose and the screws are too tight, but it does not affect the use, but the sound is a little louder.