Relay is a device that uses an electromagnet to operate a set of switch contacts. The most simple composition consisting of conductive wire coils that wrapped around the iron core. When the coil is energized, magnetic fields that form interesting armature is used as a lever pivot switch mechanism.

1. Normal open. Contact switch is closed only when the relay is turned on.
2. Normal closed. Switch contacts open only when the relay is turned on.
3. Swap-grafting. Switch contacts move from one pole to another pole when the relay is turned on.
4. When inflows On the instantaneous coil reels, the reels will instantly turn into magnit.gaya magnetic field is what will attract broad so that the switch will work

1. Relay menggrendel. Types of relays which continue working even though the coil power source has been eliminated.
2. Relay stick. Used for fast switching low power. Made of two ferromagnetic stick that dikapsulkan in a glass tube. Coil wrapped around the glass tube.