An electrical actuator converts the input electrical energy to mechanical force to move the final control element. An electrical actuator is used where the high accuracy and speed is required. There are mainly two types of electrical actuators:
- Solenoid actuators
- Electric motors
A solenoid actuator is a device that converts electrical signal into mechanical motion. The solenoid consists of two main parts, coil and plunger. The plunger may be freestanding or spring loaded. When current is applied through the coil, the plunger will move in force according to the voltage rating specification and applied voltage.
Solenoids are used where a large and sudden force must be applied to perform a job. The force may be applied in kilo or Newton.
Electrical motors are devices which convert electrical signal into rotational force. The size of the motor varies as the demand of rotational speed.
There are two main types of motors DC motors and AC motors.
A DC motor uses a permanent magnet (PM) to produce a static magnetic field across two pole pieces. When a DC current is applied through the commutator to the armature. When a current is passed through the armature coil in the presence of a strong magnetic field, the armature starts to rotate.
This type of actuators are used in conveyor systems
A synchronous motor’s speed of rotation is determined by the frequency of the ac voltage. The rotor is a PM, and the field is provided by coil driven from the ac line. Becuase of the inertia of the PM, the starting torque is not very high, but once the rotation is started the PM will rotate in phase with the field reversal caused by the oscilation of ac line voltage. Hence the rate of rotation is determined by the ac line frequency.