2) Starter contacts are indicated either for their position or for their function. In such a case, normally closed contact means that they are

in closed condition in all the status of relay

open when the relay coil is de-energised

open when the relay coil is energised

closed when the relay coil is energised

Answer is:

open when the relay coil is energised

current sensing relay

under current relay

voltage sensing relay

latching relay

Answer is:

Under current relay

Voltage sensing relay

Latching relay

Current sensing relay

Answer is:

Impulse relay

Dry reed relay

Thermal relay

Free relay

Answer is:

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

Answer is: