CONTACTORS

contactors

v  Contactors operate in the same way as a relay.

v  Typical features of a contactor are.

Ø  Double switching.

Ø  Positive action contact.

Ø  Closed chambers.

Contactor

Contactor working theory

v   These design features allow contactors to switch much higher currents than relays. 

v  A contactor has multiple switching elements, normally four to ten contacts.

v  Various types.

Ø  Normally open contact.

Ø  Normally closed contact.

Ø  Changeover contact.

Ø  Delayed normally closed contact.

v  Contactors that only switch auxiliary contacts (control contacts) are called contactor relay.

v  Contactors with main and auxiliary contacts re called main power contactors.

Use of contactors

v  Contactors are used for used for the following applications.

Ø  Currents of 4 to 30kw are switched via the main contacts of power contractors.

Ø  Control functions and logical associations are switched by auxiliary contacts of contactor relays.

v  In electro pneumatic controllers, electrical currents and power are low.

v  They can be implemented with auxiliary contactors.

v Main or power contractors are not required.