35 • Appendix A: Relay Operation
AirLink 7543 Gas Monitor Operator’s Manual
Appendix A: Relay Operation
Relays are offered in certain RKI devices for the purpose of activating alarms, horns, and other
equipment upon the detection of gas.
There are two key terms to remember when using relays.
•
Deactivated: refers to a relay in its normal state
•
Activated: refers to a relay in an alarm state
“Dry” Contact and “Wet” Contact Relays
In regard to power, there are two types of relays.
1. Dry Contact Relays: This type of relay does not provide power to the equipment attached to it
(i.e. if there is a light hooked up to this type of relay, it must be powered by another source).
2. Wet Contact Relays: This type of relay does provide power to the equipment attached to it (i.e. if a
light was hooked up to this type of relay, it would be powered by the relay). When using a Wet
Contact Relay, power should run through the “COMM” terminal to the end equipment.
Figure 11: “Dry” Contact Relay Configured as a “Wet” Contact
