Contactors control the electric current to the motor. Their function is to repeatedly establish and interrupt an electrical power circuit.
Starters are devices that control the use of electrical power to equipment. As the name implies, starters “start” motors. They can also stop, reverse, accelerate and protect them.
Starters are made from two building blocks: contactors and overloads.
They function as follows:
When a motor is off, it requires no current because the circuit is open. When the circuit is closed, the motor draws a large amount of inrush current – as much as 6–8 times the running current – which if not protected against, can produce enough heat to burn up the motor.
They consist of:
NEMA Freedom contactors and starters
IEC XT contactors and starters