Today a wide variety of electrical actuators are available using new advanced power switching technologies which have resulted in greatly enhanced performance. Commonly used electrical actuators:
Electric motors: Electric motors have a rotating shaft which produces angular rotation and torque. Electric motors can operate at very high speeds which can be reduced to get proportional increase in torque by means of a mechanical gear assembly or transmission. There are basically three types of electric motors.
1. DC Motors or Commuted Motors.
They operate on Direct Current and have commutators to switch the current carrying coils so that the rotation of the shaft is in same direction.
2. AC Motors or Non-commuted Motors.
They operate on Alternating Current and do not need commutators for operation.
3. Stepper or Stepping Motors.
These motors have equally spaced discrete movements called as steps. Stepper motors are turned by feeding voltage pulses to it which can be controlled by stepper motor controller to determine the step size or amount of rotation for each pulse.
Electric motors when used as actuators can be assisted by a feedback controller to keep track of the position and make necessary corrections in input accordingly.
Solenoid: Solenoid has a cylindrical winding and a ferromagnetic core in and along the axis of this cylindrical winding. When this winding is supplied with direct current the ferromagnetic core is pulled inside the cylindrical winding. Thus, a solenoid is a two-state actuator.