Under current relay

Voltage sensing relay

Latching relay

Current sensing relay

Impulse relay

Dry reed relay

Thermal relay

Free relay

placing asbestos between the contacts

providing a shading coil near the tip of the magnetic field

cleaning the dirty particles over the coil and contacts

applying varnish over the coil core

eliminate the chattering noise in relay

protect the equipment from fluctuating voltage

provide the gap between the layers of magnetic core

increase the strength of the magnetic field

No effect, remain in same operation

Chattering noise will be more

It will draw enormous current, lead to burn the relay

It will operate in high speed