Operation of Attracted Armature Type Relay:
The coil is energized by the actuating quantity current or voltage proportional to the system voltage or current as the case may be. The electromagnetic force on the armature is proportional to the square of the magnetic flux (the flux is proportional to the current in the coil) in the air gap between core and armature. As the armature is attracted and its motion is linked to the trip contacts that operate to give the trip signal.
The force of attraction increases as the armature nears the core (or as the air gap reduces). A restraining force in the form of a spring can be used to avoid unwanted operation of the armature relay for normal currents in the current coil.
Advantages:
1. Simple construction.
2. Reliable operation.
3. Unaffected by temperature changes.
4. Long life.
5. Robust construction.
0 Comments