Scribd is the worlds largest social reading and publishing site. This makes, torque per va of this relay is about three times more than that of induction disc type relay with a cshaped electromagnet. Electromagnetic relay working types of electromagnetic relays. Balanced beam type relays were used in differential and distance protection schemes. Induction cup relay modern induction cup relays have 4 or more poles the relays can be responsive to voltage and current the double actuating quantity relay can be responsive to both voltage and current the operating time characteristics depends on the type of structure modern induction cup relay may have an operating time. This relay is also called earth leakage induction type relay. Electromagnetic relay working types of electromagnetic. A set of typical timecurrent characteristics of the above relay is given in fig. Induction type relay construction detail electrical. This relay in nothing but one version of induction disc relay. Induction type overcurrent relays used in power system. Induction cup relay work in same principle of induction disc relay.
With limited functionality and identical operating characteristics for around 100 years, you would think that we have all agreed on the right way to test an induction disc relay. This is a demonstration of the working of an induction disc relay. Induction cup relay working principle construction and types. A higher than normal pickup value was caused by petroleum jelly lubricant which under high temperature conditions can migrate to the backstop. The protective relay is the device that responds to signals from the transducers by quickly initiating or allowing a control action to be implemented in order to prevent damage to the faulted equipment and to restore service as soon as possible.
Type cdg 11 overcurrent and earthfault relay general description a nondirectional heavily damped induction disc relay which has an adjustable inverse timecurrent characteristic with a definite minimum time. The induction type nondirectional overcurrent relay has a construction similar to a watthour meter, with slight modification. The conventional types of electromagnetic relays electromechanical relay has one or more coils, movable elements, contact system etc and its operation depends on whether the operating torque or force is greater than the restraining torque or force. As shown in figure below, this structure contains two separate coils on two different magnetic circuits, each of which produces one of the two necessary fluxes for driving the rotor, which is also a disc. The number of poles in the protective relay depends upon the number of winding to be accommodated. The basis construction of this relay is just like four poles or eight pole induction motor. Currenttime characteristics of an overcurrent induction disc relay. The coils of the electromagnets are energised with the help of alternating currents. Ca generator differential relay is a single phase, induction disc type with inverse timing characteristics. This principle says, a torque is produced by two phase displaced fluxes, which is proportional to the product of their magnitude and. Types of relay elements induction disc moving coil. The operating time is inversely related to operating current which permits close coordination with other protective devices. It also covers power system, transformer protection and zone of protection. Included in the relay are two sets of shading coils and reluctance paths responsive to the same input signal for applying the.
They are not usable with dc quantities, because of their principle of operation. The use of these relay becomes absolute as sophisticated induction disc type relay and induction cup type relays supersede them. It is a type of a magnetic switch which uses the magnet for creating a magnetic field. In these relays, a metallic disc is allowed to rotate between the two electromagnets. Electromagnetic induction relays and its structure. Induction type overcurrent relays used in power system protection electromagnetic induction relays are the most widely used relays for the protection of primary distribution in the country. The ratio of reset to pickup is inherently high in induction relays because their operation does not involve any change in the air gap.
However, i think your talking about a reluctance torque relay. Induction cup type relays are discussed with detailed explanation and important previous year questions. The magnetic field then uses for opening and closing the switch and for performing the mechanical operation. The type cvr1 voltage regulating relay is in reality a control package designed to control load tap changers. The relay operates when the operating force is greater than the restraining force.
Induction type relays are the most widely used for protectiverelaying purposes involving ac quantities. The induction type relays are also called magnitude relays. Most of the students find it difficult to understand how the shaded pole structure looks like, in this course infographics are displayed and principle is discussed with neat. Type co circuit opening overcurrent relay instruction leaflet. Change in characteristics over a period due to ageing effect. Example of electromechanical relay disc type time overcurrent. The basic principle on which induction cup relay works is same as that of induction motor. Conversely, ten induction disc relays of the same model will have identical functionality that is rather limited compared to their digital counterparts. An induction type relay is a splitphase induction motor with contacts. Induction disc relayconstruction,working electrical edition. These work on the principle of electromagnetic induction.
These relays operate on the principle of electromagnetic induction and therefore can be used on ac circuit only. The watthour structure type relay works as an electromagnetic induction type of watthour a meter so named, after it. It consists of a magnetic core operating coil, an induction disc, damping magnet, and a mechanical target. Is the pick up value the value at which the disc start. The different types of structures that have been used for obtaining the phase difference in the fluxes and hence the operating torque in induction relays are. Figures 3 and 4 show the induction unit mounted in the cradle. The figure below shows the constructional of nondirectional induction type overcurrent relay. Induction cup relay is also a type of induction disc relays. The iac relay may also include one or more hinged armature instantaneous overcurrent units, with integral target. Basic relays electromagnetic attraction and induction relays. Visit principle of induction type relay to know about the working principle. Type cdg 14 extremely inverse time overcurrent and earth fault relay a high set overcurrent unit type cag can be fitted in the same case to provide instantaneous protection under maximum short circuit conditions see application sheet r5087.
Depending on the type of rotor whether a disc or a cup the relay is known as an induction disc or an induction cup relay. Induction disc type relay mainly consists of one rotating disc. Shaded pole induction disc type relays are the second widely used relays in the power system protection in india. The cap15b relay is a threephase, highspeed induction cup power relay that is similar to the. These relays work on the principle of the induction motor or an energy meter. The basic principle of induction type energy meter is electromagnetic induction. Practically, a relay is an amplifier, since it is able to control a high power output through a low power input. The overcurrent relay operates when the current in the circuit exceeds a certain preset value. Operation of induction type overcurrent relay electrical. Induction disc type non directional over current relay or induction type over current relay. Principle of induction type relays electrical concepts. Closeup of an inductiontype overcurrent unit, showing the disc rotor and. Actuating force is developed in a movable element that may be a disc or other form of. This explains induction relays types shaded pole relays,watt hour meter relays,induction cup relays.
The working principle of a balance beam relay is quite simple. Induction disc type non directional over current relay or. The operating characteristics of the more commonly used protective relays are described in this section. High, low and adjustable speeds are possible, and various shapes of time operating quantity curves can be obtained. Electromagnetic relays are those relay which operates on the principle of electromagnetic attraction.
At room temperature the lubricant can become adhesive and. The initial force is developed on the moving element that may be disc or. Because of its low pickup, this device is basically a reverse power relay. In some solidstate relays, you can combine three instantaneous and three inversetime elements in a single relay case smaller than that of one induction disk relay. A common type ofzelay used for timed overload protection is a thennal overload relay. If magnetic saturation of the poles can be avoided by designing, the operating characteristics of the relay can be made. Current from the secondary induces an electromagnetic field which exerts a force on the disc. The induction unit is the basic unit in all type iac relays. Instructions for type cvr1 voltage regulating relay. Insert bookletgek34054 time overcurrent relay type iac model iac53t forms 800 and up. Type cdg 14 extremely inverse time overcurrent and earth. The relay has a high torque movement combined with low burden and low overshoot.
Download as pptx, pdf, txt or read online from scribd. The shaded pole type gives the most effective form of an electromagnet since it has the following higher torqueva. These units are of the induction disk construction type. The second unit is an induction disk, ac operated, adjustable timing unit. This p roduces a retarding effect on motion of the rotor in either di rection. An induction disc type relay adapted to apply to an induction disc a rotational torque proportional to an input so that an operating output is. Attraction armature relay by virtue of their construction and working principle, is instantaneous in operation. The important types of relay elements or also called electromagnetic types are. Download manual of induction disc type cdg 61 relay alstom. When no suitable station battery is available, the circuit opening type relay. Closeup of an induction type overcurrent unit, showing the disc rotor and drag magnet most electromechanical relays are typically rated for minimum input to output isolation voltages of 1500 to 2000 vac.
The driving torque on the aluminium disc is set up due to the. It contains two relaying units, over current units and the other a directional unit. Constructional details and operation of non directional over current relay wattmeter type a directional over current relay operates when the current exceeds a specified value in a specified direction. This type of relay have an operating time depending on the value of the current, generally with an inverse characteristic, the operation time of the relay is smaller as the current gets larger. Trends of protective relays 1925 induction disc type single ip relays 1961 induction cup type distance relays 1963 static type all purpose 1972 static type with self checkingall purpose 1982 digital relay first gen all purpose 1985 digital relay 2nd genall purpose over current relay operating principle in this relay there is a. These induction overcurrent relays are used to disconnect circuits or apparatus when the current in them exceeds a given value. An induction disc type relay adapted to apply to an induction disc a rotational torque proportional to an input so that an operating output is produced at the expiration of a predetermined time dependent on the magnitude of the input after the application of the input. Like an old fashioned rotating disk type elctricity meter. Harry potter would have called it one of the dark arts.