There are two types of relays, powered and un-powered. Both types of relays are designed to allow power to flow through them, the big difference is that a powered relay will already be connected to a power source (with our system it is typically a 12VDC or 24VDC source) while an unpowered relay will not have a power source connected to it. This allows the user to use it as an unpowered switch (also known as dry contact), or to connect their own power source to the relay if they wish to drive an accessory which uses 9VDC, 6VDC etc..
When trying to picture a relay, think of it as a line with a hinged section in the middle. When the relay is “Open” the hinge has swung up “opening” the relay, and interrupting any flow of power. When the relay is “Closed” the hinge has closed, completing the line and allowing power to flow through.
When using an unpowered relay, take note of the amperage rating on the relay and make sure the device you are looking to power does not require more current than the relay is rated for, otherwise you’ll be calling us for a new relay!