what is protective relays


~ protective relay are used to protect the plant and its equipment against abnormality and faults in the power system.


                              types of electromagnet relays  


1) Attracted armature types relays

2) solenoid types relays


1) Attracted armature: A type of relay winding is wrapped around a attached soft iron core.

~ a soft iron armature is performed at one end.

~  A magnetic field is generated when current is passed through the coil.

~ The force of the spring increases and the armature is attracted , thus closing the contact of the trip coil.

~ sometimes counter weight is also used instead of the string.

~ different tapping is removed from the coil to change the cut setting .


2) solenoid : it has a solenoid with an iron plunger in between.

~ when current dose not pass through the plunger stay in the decimal position by it s own weight or by  the force of the smog.

~ when a sufficient cut is passed through the relay coil a sufficient magnetic field is generated and the force applied to the plunger increases.

~ The plunger is pulled inwards.

~ The contact closes and the trip coil circuit ends.

~ when this types of relay is connected to the ac chatting of contact occurs when used on.

~ here's how chattering happens and how to get rid of it.