How does an electric relay work?

Answer 1

Relay contacts

The contacts could be in a normally open or they could be in a normally closed position depending on the type of relay it is. Most relays have their contacts in a C form configuration. This means that there is a common terminal to which the hot wire is connected and two sets of contacts one above and one below the common movable contact. In the de-energized state, between the common movable contact and the contact above will be in a N.C. (normally closed) position. This leaves the contact below and the common movable contact in a N.O. (normally open) position. The contact status is held in this position by a small spring. When the relay coil is energized, the state of these contacts reverse. The relay coils magnetism pulls on the coil armature, to which the common contact is attached, and over comes the pressure of the spring tension. The N.C contact becomes N.O and the N.O. contact becomes N.C. When reading an electrical schematic all relays contacts are drawn in the de-energized position.