Relay

A receiving instrument which moves in accordance with impulses of currents received, and in so moving opens and closes a local circuit, which circuit may include as powerful a battery as required or desirable, while the relay may be on the other hand so delicate as to work with a very weak current. IMG:8956969607833025625_456F287.jpg: Fig. 287. RELAY. The typical relay includes an electro-magnet and armature. To the latter an arm is attached and the lower end of the arm works in pivots. As the armature is attracted the arm swings towards the magnet. When the current is cut off, the armature and arm are drawn back by a spring. When the arm swings towards the magnet its upper end touching a contact screw closes the local circuit. When it swings back it comes in contact with a second screw, with insulated point, and opens the circuit as it leaves the first named screw. One terminal connects with the arm through the pivots and frame. The other connects with the contact screw through the frame carrying it. Synonym--Relay Magnet. 457   STANDARD ELECTRICAL DICTIONARY.