Electromagnetic relay working types of electromagnetic. Types cr, crc, crp and crddirectional overcurrent relays. Ic282434 induction type thermal overload relay retaining plate coil reset button fig. In these relays, a metallic disc is allowed to rotate. Induction type overcurrent relays used in power system. In induction disc type of relays, disc is the moving element on which the moving contact of relay is fixed whereas in the case of induction. Electromagnet attraction armature type relay circuit braker. The fig shows how an induction disc type over current relay with split pole i. Mohammed tawfeeq 019 t ins this characteristic can be achieved using a core of electromagnet which gets saturated for currents slightly greater than the pickup current. Aug 31, 2018 the induction disc type relay is based on the same principle as that of an ammeter or a volt meter, or a wattmeter or a watt hour mater. Induction cup type relay are used where, very high speed operation along with polarizing andor differential winding is requested. The paper focuses on how a numeric directional relay uses the phase relationship of sequence.
A relay is classified into many types, a standard and generally used relay is made up of electromagnets which in general used as a switch. Cwc and cwp the type cwc and cwp relays are induction disc type relays used for directional ground fault protection on grounded neutral power systems. The initial force is developed on the moving element that may be disc or another form of the rotor of the nonmagnetic moving element. The induction type nondirectional overcurrent relay has a construction similar to a watthour meter, with slight modification. First, we need to define the impedance between the relay and the fault location. The type kf underfrequency relay is rated 120 volts at 60 hertz, or 120 volts at 50 hertz. Relays with low voltage secondary coils provide remote control up to 36,000 feet from contact type. The watthour structure type relay works as an electromagnetic induction type of watthour a meter so named, after it. Latching relays are the same as the singleside stable relays described previously except that the core, yoke, and armature are made from semihard magnetic material and there are at least two coils in the relay. The coils of the electromagnets are energised with the help of alternating currents. Relays with low voltage secondary coils provide remote control up to 36,000 feet from contact type pilot devices. Pdf over current relay working principle posi akmal. The second unit is an induction disk, ac operated, adjustable timing unit.
Switch on the test current and check trip time of the relay. Lastly, the mammoth relay on the far right is an automotive power relay, which is rated at 60 amps. If the saturation occurs at a very early stage, the time of operation remain same over the working range. Also, connect the ampere meter into the power supply circuit for monitoring.
Aunovdec0911 it refers to the current or voltage which is used to activate the relay. 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. A rotating magnetic field is produced by different pairs of field poles. The cap15b relay is a threephase, highspeed induction cup power relay that is similar to the. Sep 01, 2018 as we said earlier, the working principle of induction cup relay, is same as the induction motor. Wattmetric and shaded pole relays of induction type. The force is developed by the interaction of electromagnetic fluxes with eddy current, that is induced in the rotor by these. The different types of structure that have been used for an induction type relay are commonly called. The type cvr1 voltage regulating relay is in reality a control package designed to control load tap changers. Abstract three phase solid state relays ssrs have been available since shortly after the introduction of single phase ssrs in 1970. Power relays cw,cwc, cwd, cwp, cwp1 electromechanical. It con sists of a steel ball resting between two hemispherical cup jewels, one fixed in the. A tapped resistor is used to enable one to use the auxiliary switch on a 24, 48, 125 or 250 volt dc.
Jan 20, 2017 this type is widely used where control is from simple switches or singleended outputs of a control system, and such relays are found in avionics and numerous industrial applications. They have earned a welldeserved reputation for accuracy, dependability, and reliability. Electromagnet attraction armature type relay circuit. Induction cup relay is very suitable for directional or phase comparison units. The relay can be polarized from a potential source, from a local ground source, or from both simultaneously.
Operating principles, directional type, 24 singlequantity type, 22 induction relays. This app covers entire aspects of the subject, from basic engineering to advanced and modern topics related to electrical engineering and technology. Set the relay and calculate the test current as follows. Apr 26, 2018 the different types of structure that have been used for an induction type relay are commonly called. The shaded pole structure the watthourmeter structure the induction cup and double induction loop structures the single induction loop structure. An induction type relay is a splitphase induction motor with contacts. These types of electromagnetic relays can be utilized as either magnitude relay or ratio relay. Electromagnetic relay working types of electromagnetic relays. Induction type relay these are used as protective relays in ac systems alone and are usable with dc systems.
The figure below shows the constructional of nondirectional induction type overcurrent relay. An induction relay works only with the alternating current. The electromagnetic relay operates on the principle of a splitphase induction motor. In four poles design both pair of poles are supplied from same current transformers secondary, but phase difference between the currents of two pole pairs is 90 deg. It produces flux in the upper, lower and right hand side poles. Actuating force is developed in a movable element that may be a disc or other form of rotor of nonmagnetic currentconducting material by the interaction of electromagnetic fluxes with eddy currents that are induced in the rotor by these fluxes. The operating characteristics of the more commonly used protective relays. This relay is also called earth leakage induction type relay. 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. Attracted armature type relay, induction disc type relay, induction cup type relay. Induction motor protection systems bachelors thesis study program. The cap15b relay is a threephase, highspeed induction cup power relay. Working of relayshow relay works,basics,design,construction. In induction relay the deflecting torque is produced by the eddy currents in an aluminium or copper disc by the flux of an ac electromagnet.
Turn up voltage slowly, and when hearing pullin sound of the relay, write down the pullin voltage and current. Different types of relays used in protection system and their. Three phase solid state relays ssrs have been available since shortly after the introduction of single phase ssrs in 1970. Numerical relay for overcurrent protection using tms320f2812. Types of relaysoverload protection relay,solid state. Principle of induction type relays electrical concepts. Here, an aluminum or copper disc is placed between the poles of an. Impedance relay, characteristic on rx diagram, 72 for line protection, 340 general, 70 see also distance relays induction cup and induction loop structures, 30, 31 induction type relay, directional, 31 general characteristics, 26 singlequantity, 31 structures, 29 torque production, 26 insulating transformer for pilotwire circuits, 98. The working principle of both type of relays are more or less some. Ic282434c thermal induction overload relay 600 500 400 max 0 300 min 200 ioo 10 ioo. 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. The type crd relay utilizes the directional unit of the crc relay in conjunction with the directional unit and phase shifting mechanism of the.
Directional over current relay linkedin slideshare. Non indirectional induction overcurrent relay construction. Timecurrent curve, slowfrip forms, 60 cycles, 40 c ambient temperature. The working principle of electromagnetic relays is not complicated, and it operates mainly according to the principle of electromagnetic induction. 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 cup relay working principle construction and types. This is the first generation oldest relaying system and they have been in use for many years. The spindle of this disc carries a moving contact which bridges two fixed contacts when the disc rotates through an angle, which is adjustable between 0 o to 360 o. Actuating force is developed in a movable element that may be a disc or other form of rotor of non. It consist of an electromagnetic system which operates on moving conductors. Induction type relay construction detail electrical concepts. In induction disc type of relays, disc is the moving element on which the moving contact of relay is fixed whereas in the case of induction cup the contact is fixed on the cup.
Connect the adjustable regulation power supply to the relay and input a set of voltages to the relay. Instructions for type cvr1 voltage regulating relay. Constructional details and operation of non directional over current relay wattmeter type it has a metallic disc free to rotate between the poles of two electromagnets em. These relays work on the principle of the induction motor or an energy meter. Ic282434c thermal induction overload relay 600 500 400 max 0 300 min 200 ioo 10 ioo seconds to trip fig. On the relay, the moving element rotor is usually a metal disk, although. The shadedpole structure as shown in figure below is generally actuated by current flowing. The induction type relays are also called magnitude relays. The type cw relay is a single phase induction type relay providing overpower or reversepower protection for electrical equipment or circuits. Caution after each test, cool the relay for minimum 10 minutes. Induction cup type relay can be considered as a different version of induction disc type relay. A single plate induction cooker with the st7flite09y0 introduction this application note describes an induction cooking design which can be used to evaluate st components or to get started quickly with your own induction cooking development project. In these relays, a metallic disc is allowed to rotate between the two electromagnets. They were first invented in 1835 by joseph henry, the man who also discovered electromagnetic induction.
Also, the design, construction, working, applications, and also relay selection is explained in detail. Depending upon working principle the these can be divided into following types of electromagnetic relays. Jul 14, 2016 the fig shows how an induction disc type over current relay with split pole i. The operating time of these relays is also a function of two additional constants. A simplest form of electromagnetic induction type reactance relay induction cup is shown in the figure. This is because, besides the sensitivity, induction cup relay have steady non vibrating torque and parasitic torques due to current or voltage alone are small in induction cup directional or power relay. It is not intended for use as a fault protective relay. The electrical protective relay can be broad, classified into two categories i electromagnetic relay and ii static relay.
Aug 21, 2017 attraction armature type relay is the most simple in construction as well as its working principle. A bw controls system consists of three main components. Practically, a relay is an amplifier, since it is able to control a high power output through a low power input. This is done by inserting an inductor in series with coil. A single plate induction cooker with the st7flite09y0. Otherwise, relay will trip early and you will not get correct results. Electromagnetic relays are those relay which operates on the principle of electromagnetic attraction. Because of its low pickup, this device is basically a reverse power relay. According to the principle of operation and construction, the relay may be classified such as the electromagnetic attraction type, electromagnetic induction type, electrodynamic type, moving coil type. Operating state set when current flows through coil a, the electromagnet made of. Induction relays are available in many variations to provide accurate pickup and timecurrent responses for a wide range of simple or complex system. Apr 26, 2018 an induction type relay is a splitphase induction motor with contacts.
In this article, the basics of a relay like energized relay and deenergized relay are explained in detail. The induction disc type relay is based on the same principle as that of an ammeter or a volt meter, or a wattmeter or a watt hour mater. The overcurrent relay operates when the current in the circuit exceeds a certain preset value. Westinghouse induction type overcurrent and directional overcurrent relays i contacts j t1rf. The above figure shows the wattmeter type induction relay. The major com ponents of the cvr1 relay are an induction disk type voltage sensitive relay, two atl\. According to the principle of operation and construction, the relay may be classified such as the electromagnetic attraction type, electromagnetic induction type, electrodynamic type, moving coil type, electrothermal. The first of these relays were nothing more than 3 individual ssrs. It is a type of a magnetic switch which uses the magnet. Basic relays electromagnetic attraction and induction relays. Electrical engineering, power engineering and management.
1232 580 693 1215 1589 504 1201 1089 66 494 1053 1134 742 818 1349 1070 1631 322 14 979 1284 273 1542 1298 1483 1145 121 78 1030 186 1484 474 1186 1024