Polarized relay are made up of electromagnetic coil and a permanent magnet. Some relays are magnetically polarized other by using a diode in series with the coil that prevents the current flow in reverse direction. Polarized relay is a type of relay whose switching depends on the direction of the current flow through the coil.
Most differential relays are protective relays used to protect the systems. They activates when the specified difference exceeds or decrease a fixed limit. Such type of Relay coil does not get affected by alternating current.ĭifferential relays operate on the difference between two electrical quantities. Most card access relays are wireless relays that identify the card & wirelessly passes the signal to the relay to activate or deactivate. This is an electronic relay that operates on special cards. When there is a voltage fault in the line that could cause damage to the equipment, the relay activates to prevent such damage.
Such type of protection relay is activated by defective voltage in line.
They are used for instant switching applications. The coil of such relay energizes or de-energizes as soon as the power supply is applied or removed respectively. This is a fast switching relay that can instantly switch from activated state to deactivated state very fast & vice versa.
