AC Contactors and its Applications

Contactors and relays are often considered similar. You will regret if you ever specify a relay in a situation that calls for a central air contactor. Both switches are electrically operated and are employed for control and switching of loads. Contactors can handle up to 10A or above, whereas relays operate below 10 amps.

Difference between Contactor and Relay

Relays          

It is mainly used for switching small electronic circuits, control and automation circuits and protection circuits.           

It is used in circuits with lower ampacity.  

It is very smaller in size.      

It has at least two NO/NC contacts.            .

Contactors

In few cases auxiliary contacts are also provided.

It is used in circuits with both low and higher ampacity.

Even used in the switching of lights, motors, capacitors etc.

It contains minimum of one set of three phase power contacts.

Compared to relays these are larger.

Applications of Contactor

Relays are reserved for single phase whereas three phase applications call for contactors. Reason behind it is that a relay only has a common contact that connects to a neutral position. Without any common circuit a contactor joins two poles. AC compressor contactor is good for situations up to 1000 volts while relays are comfortable in situations up to 250 volts AC.

It becomes necessary to consider the function that you want the component to serve in your system. In situations where an overload can take place contactors come as a rescue and the failure to de-energize the circuit will keep people and/or the system in danger. Relays can never provide this protection.

Thus, the use of contactors is typically to switch slighting systems, high-current motors and capacitors. You can also fit contactors with auxiliary contacts to provide them the capability of operating in a normally closed condition. In such configuration, switching can take place irrespective of whether the contactor’s coils are energized or de-energized.

The Bottom Line

The primary situation involving use of ac contactors is any high-powered circuit having an overload condition taking place. This is very much true if you leave the circuit in an energized state and this will create a hazardous environment for people as well as for any equipment. Follow us on Facebook