At its core, a 30A power relay is an electromechanical switch that allows low-power circuits to control high-power electrical devices. The term “30A” refers to the maximum current rating the relay can handle, meaning it can safely control circuits that carry up to 30 amperes of electrical current. Typically, the relay operates on a 12V or 24V input signal, which activates an internal electromagnetic coil. When the coil is energized, it pulls a set of contacts together (or pushes them apart), thereby closing or opening the electrical circuit of the connected load.