The power relay is a term used to any switch which has an electromagnetic coil and deploys it to turn on and off an electric circuit. It consists of several components including an armature, a spring and contacts. The design of the power relay was done purposefully to allow a normal opening once power is switched on, then the coil which has electromagnetism will pull an armature, then an armature is attracted into the coil’s direction. A movement continues to the contact, once an armature arrives a closing of the circuit occurs.
If a design of the relay switch was done to allow a normal closing, then the electromagnetic coil pushes away the armature. Pushing is done away from the contact. Once this is complete the circuit opens. The operation of the system could be done using low voltage though the conduction of high voltage is possible too.
Due to a wide range of voltage that could be conducted, they are useful in many different systems. Such systems are not limited to audio amplification in automobile electrical appliances and telephones.