Shaded Pole Relay

 Shaded Pole Relay

Shaded pole relay consists of aluminum disc, which is pivoted such that it freely rotates in the air gap of an electromagnet. 

Shaded ring or copper ring is surrounded on one half of each pole. 

The induced currents in this shaded ring produce another flux called as

shaded flux, which lags behind the flux produced by the unshaded pole by some angle.

The phase difference between these two fluxes produces necessary torque to rotate the disc.