Single phase application
Consist of a COIL,NO,NC and Common
When Coil get energized common switches from NC to NO
Thus O/P connected with NO works.
Three phase application
Consist of a COIL and 3 NO
When coil get energized 3 PHASES (R, Y and B) will switch to o/p.
What is NC contact ?
Normally Closed contact - Basically normally closed switching is used were it requires to break or OFF a circuit.
What is NO contact ?
Normally Open Contact - Basically normally open switching is used were it required to ON a circuit.