Relays are the best way to switch high-amperage loads (such as fans, horns, or lights). You can use a compact switch with a relatively low amperage rating to control an accessory drawing more than 10 Amps.
Change Over Relays offer three different operation modes for great versatility:
Normally Open (NO): Current is switched on when power is applied to the relay
Normally Closed (NC): Current is switched off when power is applied to the relay
Change Over (NC/NO): Current is transferred from one circuit to another when power is applied to the relay
The Normally Open function can be used to supply power (up to 50 Amps @ 12 VDC) to cooling fans, electric pumps, or headlights. The Normally Closed function can be used to cut off power (up to 30 Amps @ 12 VDC) to fuel transfer pumps, preheaters, or solenoids. The Change Over function combines the Normally Open and Normally Closed functions for advanced switching of reversing motors, dual pumps, or two-speed fans.
Standard ISO 5-pin arrangement fits our Pre-Wired 5-Pin Relay Socket (Part No. 4411-021, sold separately). The molded plastic body has an extended tab with a 1/4" hole for easy mounting. Maximum 20 millisecond make/break time. Requires 8-16V power to operate relay (the common 5v output voltage from most data loggers is too low).