Contactors

Contactors are one of several relay-type switches. Generally (but not always) a lower voltage activates one or more higher-voltage switches. The switch is activated without a delay. For example, a thermostat calling for A/C will send 24V to the contactor which then closes a 240V switch to immediately start the air-conditioning condensing unit. Sequencers and relays are similiar to contactors. Of the three, contactors are considered the most heavy-duty switch. Sequencers generally incorporate a delay.