Contents
How do you size an electrical contactor?
As per above chart:
- Type of Contactor = AC7b.
- Size of Main Contactor = 100%X Full Load Current (Line).
- Size of Main Contactor = 100%x6 = 6 Amp.
- Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
- Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.
What are the key factors to be considered in selecting a contactor?
The choice of contactor is dependant upon many parameters i.e. operating voltage, size of contacts, number of operations, ambient temperature, type of load supplied etc. Loads are categorised into various AC ratings, (AC1, AC2, AC3 etc.) and the higher the AC rating the more inductive the load becomes.
What does a contactor do in a circuit?
A contactor is an electrical device which is used for switching an electrical circuit on or off. It is considered to be a special type of relay.
Can a contactor be used in a control circuit?
The coil voltage of a contactor or relay can be installed for virtually any control circuit voltage, to provide complete flexibility for these devices (both AC and DC), as the control circuit can be completely independent of the load it is switching.
Contactors and relays are operated by applying a voltage to the coil of an Electro-magnet, which will cause a switch, (or several switches) to close. The circuit that applies the voltage to the coil is referred to as the control circuit, because it controls the main device that the contactor or relay is switching.
Where are the main contacts located in a contactor?
A spring which is located between coil and the movable core, auxiliary contacts it could be normally open or closed. The main contacts cut on and off the light current loads such as contactors coil, relays, timers, and many other control circuit parts are linked to contact mechanism.
How is an electromagnet rated for a contactor?
When the contactor coil is de-energized, gravity or a spring returns the electromagnet core to its initial position and opens the contacts. Contactors are rated by designed load current per contact (pole),maximum fault withstand current, duty cycle, voltage, and coil voltage.