These are the tests that are carried on the relays which are employed for high and medium power switching or protection system applications. But, in case of high cost circuits or equipments, it is desired to adopt a protection system or protection circuit and controlling device or controlling circuit to avoid economical loss and damage. Place the selector of multimeter in resistance mode and measure the resistance of the relay coil. Keep the multimeter selector in the continuity mode. In any type of electromechanical relay of the relay, the major components are coil, armature and contacts. These are again classified into several types such as hinged armature type, plunger type, balanced beam type, moving coil type and reed type relays. Place the multimeter probes such that one probe at pole and other at NO contact and check for the discontinuity between the pole and NO contact. The electrical quantities which may change under fault conditions are voltage, current, frequency, and phase angle. Best Solar Panel Kits Therefore, in order to ensure the reliable performance of the relay, it must be tested before putting into service and also after time intervals it must be checked. Operation of a 12 A relay A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core (a solenoid), an iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of contacts (there are two contacts in the relay pictured). Relays can be used for switching as well as protection application. If the relay coil is energized by giving supply to the coil terminals at ‘C’, then the movable contact of the relay is attracted towards the fixed contact. Though the SPDT has two output positions, it may consist of more than two throws depends on the configuration and requirement of the application. 6. Thanks. In Electromagnetic Attraction Relays, there is a coil which energises an electromagnet.When the operating current becomes large, the magnetic field produced by an electromagnet is so high that it attracts the armature or plunger, making contact with the trip circuit contacts.These are the simplest type of relays. There are numerous ways to operate a DC relay using different types of control devices ranging from simple transistor devices to high end integrated type devices. The Relay detects the abnormal condition by continuously monitoring electrical quantities which are different Great Work. 9.2 Principle of the Construction and Operation of the Electromechanical IDMTL Relay. This book contains a description of electrical relays, their principles of operation, and applications for all basic types, for as widespread as knowledge of the subject is, it is still not abundant. When the switch is open no current passes through the relay, the circuit is open, and the load that is connected to the relay receives no power. Finally remove the power supply. Thus, the relay turns on and the supply is connected to the load as shown in the below figure. Induction type relays are classified into shaded pole, induction cup type and watt-hour meter relays. All the Relays react to voltage or current with the end goal that they open or close the contacts or circuits. Relay is a switch which senses fault in a system and once fault is sensed by the Relay, it issues trip command to the Circuit Breaker, CB to isolate the faulty section of the network from the healthy section. Breadboard Kits Beginners An electromechanical relay consists of three terminals namely common (COM), normally closed (NC) and normally opened (NO) contacts. When the coil is applied with DC current it starts attracting the contact as shown. A low power control circuit is needed to supply the base current in order to turn ON or OFF of the transistors. These are signal in (or input) and signal out (or output) terminals. FM Radio Kit Buy Online The current flowing in one circuit causes the opening or closing of another circuit. This is performed by the manufacture at several stages during manufacture in order to check the acceptability of the unit for sale. These tests are carried to identify the degradation of the service and equipment failures in the relay. Best Iot Starter Kits Led Christmas Lights A relay is usually an electromechanical device that is actuated by an electrical current. This relay is also called as changeover relay. Required fields are marked *, Best Rgb Led Strip Light Kits It works on the principle of an electromagnetic attraction. You could use some kind of electronic thermometer circuit tosens… In an over electric current relay or o/c relay the actuating quantity is only current. The relay is an electromechanical switch used as a protecting device and also as a controlling device for various circuits, equipments, and electrical networks in a power system. An armature is a movable part and its main function is to open or close the contacts. Protection systems of electrical power system. The electromagnetic force experienced on the armature or plunger is proportional to the square of the current or the square of the magnetic flux in the air gap. Because these sensors play a key role in detecting the objects that are approaching. Relays are like remote control switches and are used in many applications because of their … In this the relay coil is connected between the emitter and ground terminals. Therefore, both the contacts are remains untouched and there exists a small air gap between these contacts. Reclosing relays are used to connect various components and devices within the system network, such as synchronizing process, and to restore the various devices soon after any electrical fault vanishes, and then to connect transformers and feeders to line network. Relays are used to protect the electrical system and to minimize the damage to the equipment connected in the system due to over currents/voltages. Best Robot Dog Toys There are various types of relays such as Buchholz relay, latching relay, polarized relay, mercury relay, solid state relay, polarized relay, vacuum relay, and so on. In the beginning, electromechanical relays were used to transfer the Morse-code signal to long-distance through a wire. In these relays, the actuating force is developed by the moving contact which can be a disc or cup through the interaction of two alternating magnetic fluxes on a magnetic element. It works on the principle of comparison between the phase angle and the magnitude of the same electrical quantities. Basically, a relay has three contacts which are necessary to connect the two circuits but the way these contacts are configured or switching action of the contacts, relays are classified into different types. An electromechanical relay is a device that controls one electrical circuit by opening and closing contacts in another circuit. This switching operation can be performed either manually or automatically. Construction and working principle of instantaneous over current relay is quite simple. A monitoring relay whose function is to limit the operation of associated protective relays to specific field protective relay A relay that functions to prevent overheating of the field excitation winding by reducing or interrupting the excitation of the shunt field. The small power relay has only one contacts, and the high power relay has two contacts for opening the switch. 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