Types of relay and their working principle pdf

What is relay and different types of relays pdf elprocus. The reed relay consists of a switch with magnetic contacts that move under the influence of an external magnetic or the induced field from its solenoid. The working principle is that if the current is in excess then the strip would melt and break the circuit. As we have discussed, a relay allows for switching a high power circuit with a low power circuit. Relays consist of an electromagnet and also a set of contacts. The relay is the device that open or closes the contacts to cause the operation of the other electric control. The working principle of the solid static relays is. Thus the switch plays an important role in the relay working. Minimum voltage drop in starter cables is necessary to ensure sufficient starter speed and torque. Relay explained and animated how relay works youtube. It was invented at bell telephone laboratories in 1936 by w.

Learn what is a relay, how a relay works, how it is designed and constructed and what are the different types of relays based on their working principle and polarity. Only some of the relays are explained in this document for. Working of relayshow relay works,basics,design,construction. A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. It is used for not disrupting the continuity of the circuit. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as. Power transformer working principle, construction and types. The information in the book is arranged such that the reader can work with any. Attraction armature relay by virtue of their construction and working principle, is instantaneous in operation. A strip of this fuse is placed in series with the circuit. This magnetic field moves the relay armature for opening or closing the connections. Through the changes in one or more of these quantities, the faults signal their presence, type, and location to the protective relays. Types of relaysoverload protection relay,solid state.

Starting system principle of operation electric starter motor the electric starter motor converts electrical current into rotary motion. In describing some of the complicated types of relays for example. In this post, i will discuss what is a transformer, its working principle, transformer construction, types of the transformer and transformer testing. The solid static relays use analogue electronic devices instead of magnetic coils and mechanical components to. There are different variants of fuse boxes available with different types of circuit breaking. In doing so it converts electrical energy into mechanical energy. This p roduces a retarding effect on motion of the rotor in either di rection. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. Sep 07, 2016 the working principle of this breaker is rather different from those in any other types of circuit breakers.

The main aim of all kind of circuit breaker is to prevent the reestablishment of arcing after current zero by creating a situation where in the contact gap will withstand the system recovery voltage. The basic purpose of the fuse is to protect and is composed of an alloy which has a low melting point. Types of electromagnets relays are classified into the following types, depending on whether or not they have a permanent magnet. You can check the live working of the relay in below given animation. Relay explained and animated a relay is an electrically operated switch. Types of relays there are different ways to classify relays. The electrical quantities which may change under fault conditions are voltage, current, frequency, and phase angle. Types of electrical protection relays or protective relays. Relays are classified into several types based on their functionality and application they are implemented for. Different types of relays, their construction, operation. This is about electromagnetic attraction relays, working of electromagnetic attraction relays, construction of electromagnetic attraction relays, types of electromagnetic attraction relays and also advantages,disadvantages,applications of electromagnetic attraction relays, balanced beam electromagnetic attraction relay. Mar 25, 2017 different types of solid state relays ssr and their working classification of solid state relays ssr ssr definition.

It works on the principle of an electromagnetic attraction. Electromagnet attraction armature type relay circuit braker. Servo motors are classified into different types based on their application, such as ac servo motor, dc servo motor, brushless dc servo motor, positional rotation, continuous rotation and linear servo motor etc. Typical servo motors comprise of three wires namely, power control and ground. A transformer has no moving parts and is a completely. We know that most of the high end industrial application devices have relays for their effective working. Therefore, this document is intended to describe about a few basic types of relays that are popularly used in typical loadcontrol. A solid state relay may be defined as an electrical switch that changes its state when an external voltage is applied to it. Types of relay based on the principle of operation. Protective relays work in concert with sensing and control devices to accomplish their function. An electrical relay that works by the suction force generated between the electromagnet core and the armature by the circuit inside the input circuit.

For instance, in the case of slow blow fuses, a small overload is carried for some period without the circuit been broken. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solidstate relays. The magnetic field then uses for opening and closing the switch and for performing the mechanical operation. It closes the next circuit before breaking opening the first circuit.

Types of relays and relay driver circuit buchholz relay. Different types of relays and their working principles. Here we shall consider plungertype and attractedarmaturetype ac or dc relays that are actuated from either a single current or voltage source. Actually, a relay is nothing but a combination of one or more open or closed contacts. The value of current or voltage below which a relay opens its contacts and. They have faster switching speed compared to the electromechanical ones but their switching current and voltage is lower mainly because of its contacts thickness. Jun 08, 2019 types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Different types of relays used in protection system and their. Nonpolarized relays nonpolarized relays do not use a permanent magnet in their. These relays are constructed with electrical, mechanical and magnetic components, and have operating coil and. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Form d relay is also an spdt relay and has the same principle as form c relay but it is makebeforebreak contact relay.

In this relay, the armature is attracted to the pole of a magnet. Another instance in which this relay can be used is when the windings of a machine have two identical parallel subwindings per phase. Types and revolution of electrical relays introduction. When the circuit of the relay senses the fault current, it energises the electromagnetic field which produces the temporary magnetic field. A relay is classified into many types, a standard and generally used. These types of electromagnetic relays can be utilized as either magnitude relay or ratio relay. The heart of a relay is an electromagnet a coil of. Depending upon working principle these can be divided into following types of electromagnetic relays.

This document explains each and every relay and its working principle with appropriate figures. In addition to having different operating types, relays can have their contacts arranged in various configurations depending on the use. But when fault or undesirable condition arrives relay must be operated and function correctly. Relays can be classified into different types depending on their functionality, structure, application etc. The switching mechanism is carried out with the help of the electromagnet. The working principle of the solid static relays is similar to that of the electromechanical relay which means the solid static relays can perform tasks that the electromechanical relay can perform. Types of relay, terminals of relay, application of relay, control input or coil. There are also other operating principles for its working. Having detected the fault, the relay operates to close the trip circuit of the breaker. There are four common types of relays that we briefly discuss each of these relays has only solenoid coil, but a varying number of power contacts. Also, it works as a circuit breaker or stabilizer which protects the device from damage. There is only one current operated element in the relay, no voltage coil etc. In an over current relay or oc relay the actuating quantity is only current.

After relay operation, these types of electromagnetic relays are reset manually. In other words, when the relay control coil is not energized, the relay. Different types of relays and their working principles elprocus. The transformer is a common word for an electrical engineer and engineering student. Electromagnetic relays are those relay which operates on the principle of electromagnetic attraction. The following groupings will be used in this technical guide.

Under normal power system operation, a protective relay remains idle and serves no active function. Aug 21, 2017 attraction armature type relay is the most simple in construction as well as its working principle. Security the contactor relay contacts themselves constitute a considerable safety feature. Attracted armature type relay, induction disc type relay, induction cup type relay, balanced beam type relay, moving coil type relay, polarized moving iron type relay. Oct 14, 2016 a relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. Different types of solid state relays ssr and their working. The operation of a normally closed relay is the same to that of a normally open relay, except backwards. Based on operation principles, emr electromechanical relay, ssr solid state. Other than the electromagnetic relay there are many other types of relays which work on different principles. Electromagnetic relay working types of electromagnetic.

Both ac and dc relays work on the same principle as electromagnetic induction, but the construction is. Ssrs, however, employ semiconductor switching elements, such as thyristors, triacs, diodes, and transistors. Classified according to the working principle or structural characteristics of the relay. So to make a relay operate, we have to energize the coil by passing a current through it. By their working principle, the electromagnetic relay is mainly classified into two types. A solid state relay ssr is a re lay that does not have a moving contact. Reed switch working principle the reed switch is an electrical switch operated by an applied magnetic field. In the market, many types, features, and design of fuses are available nowadays.

You can choose from a wide range of relays but do you know what type to. In terms of operation, ssrs are not very different fr om mechanical relays that have moving contacts. By design and construction they ensure potential isolation between the actuating circuit and the operating circuit, in the deenergized state, between the contact input and output. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. Reed switch working principle instrumentation tools. These classifications include electromagnetic, solid state, high voltage, thermal relays, and so on. This book contains a description of electrical relays, their principles of. Concept and working of different types of fuses protection. It can be designed to step up or step down voltages and works on the magnetic induction principle. A relay is an electromagnetic switch that is used to turn on and turn off a circuit by a low power signal, or where several circuits must be controlled by one signal. Types of protection relays are mainly based on their characteristic, logic. All dil contactor relays have doublebreak contacts. Relays are simple switches which are operated both electrically and mechanically.