Common Types of Electrical Actuators Flashcards
What is the function of an actuator?
It receives the signal from the controller and modifies the process variable accordingly
What is a servomechanism?
It is an actuator that has mechanical output
What are three categories of actuators?
- Electrical
- Hydraulic
- Pneumatic
What function does the solenoid perform?
It accepts electrical signals and provides linear mechanical motion
What function does the servomotor perform?
It accepts electrical signals and provides rotary mechanical motion
What is a clutch used for?
To quickly engage, disengage or control the speed of the device it is actuating
The stepper motor can be classified as a/an _____ motor (DC or AC)
DC
What are three basic types of stepper motors?
- Variable reluctance
- Permanent magnet
- Hybrid
How can a stepper motor be reversed?
By reversing the sequence of stepping (i.e., the opening and closing of the switches) for stator windings
What advantage can be gained by using half-step vs. full-step energization modes?
Increased step resolution (more positions)
How can step resolution be increased in a motor?
By increasing the number of poles on the stator and the rotor and machining more teeth on them
What type of stepper mode is most commonly used?
Four-step mode
A stepper motor advances 2.5° per step. How many pulses are needed to complete one revolution?
144 pulses
What are two uses of an encoder?
To measure shaft position and shaft speed
What are three basic parts of an optical encoder?
- Light source (LED)
- Disk with transparent and dark patterns
- Photo sensor
