Contactors and Overload Relays are suitable for a large variety of applications in building and in industry such as motor control, heating and ventilating, air conditioning, pumping, lifting equipment, lighting, process power factor correction.

Some application of contactors:

1- Start/stop circuit

I. Power & control circuit

II. Operation

a. When Press S1 (start pushbutton)
b. Contactor k1 operate ,then contact k1 will be normally close
c. Motor will operate ,until press S0 (stop pushbutton).

III. PLC ladder diagram

2- Start/stop circuit from 2 position

I. Power & control circuit

II. Operation

a. When Press S3 or S4 (start pushbutton)
b. Contactor k1 operate ,then contact k1 will be normally close
c. Motor will operate, until press S1 or S2 (stop pushbutton).

III. PLC ladder diagram

3- Reverse motor with stop circuit

I. Power & control circuit

II. Operation

• To operate the first direction Press S2 (start pushbutton) ,Contactor k1 operate , then contact k1 will be normally close Motor  will operate in first direction.
• To operate the second direction press S1 (Stop pushbutton) ,Contactor k2 operate , then contact k2 will be normally close
• Motor will operate in second direction.

III. PLC ladder diagram

4- Star/Delta Circuit

I. Power & control Circuit

II. Operation

• When press S1 (Start pushbutton) ,k3 will operate and then contact k3   will be normal close
• timer T1 & contactor K1 will operate motor operate in stare mode
• after a period of time ,contact t1 became normally close then contactor k2 will operate motor operate in delta mode until pressing S0 (stop pushbutton)

III. PLC ladder diagram