1 (not included here), have either a solenoid that pulls in a plunger, or one or more electromagnets that attract a hinged armature. The electromechanical protective relay converts the voltages and currents to magnetic and electric forces and torques that press against spring tensions in the relay. Electromagnetic-induction relays use the principle of the induction motor whereby torque There are two basic types of operating mechanisms: the electromagnetic-attraction relay and the electromagnetic-induction relay. The main working principle of the relay is the electromagnetic attraction. Actuating force is developed on a moving element, that may be a disc or other form of rotor of non-magnetic current-conducting material (such as aluminium), by [â¦] Magnetic-attraction relays, as shown in Fig. Electromagnetic Induction: Relies on the reaction between two magnetic fields to apply a torque on a movable disc or cup that allows rotation and hence closing of contacts. The relay is the device that open or closes the contacts to cause the operation of the other electric control. 4 I N D E X Evaluation of protective relaying, 12 Expulsion protective gaps, effect of, on distance relays, 367 13. Magnetic attraction relays . Electromagnetic induction relays use the principle of the induction motor whereby torque is developed by induction in a rotor. How Electric Relay looks 14. The electromagnetic attraction type relays operate on the principle of attraction of an armature by the magnetic force produced by undesirable current or movement of plunger in a solenoid. How Electric Relay Works 15. ADVERTISEMENTS: Electromagnetic induction relays are the most widely used relays for protective relaying purposes involving only ac quantities. The electromagnetic relay hard working based on the principle of electromagnetic attraction or electromagnetic force. Electromagnetic Attraction: Current through a coil with an iron core produces a magnetic attraction. Electromagnet - Electromagnet - Relays. The same device applied in heavy-current circuits is called a contactor, or circuit breaker. Electromagnetic-attraction relay, directional, 24 general characteristics,, 16 single-quantity, 22 Electronic relay, directionalcomparison pilot, 396 distance, 369. AC electromagnetic relay: An electromagnetic relay whose control current in the input circuit is AC. These relays operate on the simple principle of split-phase induction motor. The release is a type of magnetic switch is uses the magnet to create a magnetic field. Such relays may be actuated by d-c or by a-c quantities. : A relay is a device in which the solenoid principle is applied to opening and closing light-current electrical circuits. The various types of these relays are. Electromagnetic induction Electromagnetic attraction relays operate by virtue of a plunger being drawn into a solenoid. Magnetic latching relay: The magnetic steel is introduced into the magnetic circuit. Elect romagnetic attraction relays operate by virtue of a plunger being drawn into a solenoid, or an a rmature being attracted to the poles of an electromagnet. Usually an electromagnetic relay has two circuits, low-voltage control circuit and high-voltage working circuit.The low-voltage control circuit includes an electromagnetic relay coil, a low-voltage power supply and a switch. Electromagnetic-attraction relay and; Electromagnetic-induction relay; Measuring Principles. After the relay coil is de-energized, the armature of the relay can still be maintained in the state when the coil is energized, with two stable states. These relays can be actuated by AC or DC quantities. Electromagnetic attraction 2.