V.R.study⚡️💡

AB Switch = Air Break switch ACB = Air Circuit Breaker VCB = Vacuum Circuit Breaker MCB = Miniature Circuit Breaker MCCB = Molded case circuit breaker MPCB = Motor Protection Circuit Breaker EMPR = Electronic Motor Protection RELAY RCCB = Residual Current Circuit Breaker RCBO = Residual Current Circuit Breaker With Over-Current Protection ELCB = Earth Leakage Circuit Breaker HRC = Fuse High Rupture Capacity Fuse OLTC = On Load Tap Change SF6 Circuit Breaker = Sulphur Hexafluoride Circuit Breaker MPDB = Main Power Distribution Board ACDB = Alternating Current Distribution Board HT = High tension > Transformer HT Side LT = Low tension DO Fuse = Drop Out Fuse DCDB = Direct current Distribution Board PDB = Power Distribution Board PCC = Power Control Center MCC = Motor Control Centre MCP = Motor Control Panel VVVF = Variable Voltage Variable Frequency Drive VFD = Variable Frequency Drive DOL = Direct On line RDOL = Reverse Duty on Line MLDB = Main Light Distribution Board SLDB = Secondary Lighting Distribution Board EMLDB = Emergency Light Distribution Board CPSS = Construction Power Substation DSS = Distributed Power Substation RCC = Remote Control Cables FCMA = Flux Compensated Magnetic Amplifier UPS = Un-Interrupted Power Supply SMF Battery = Sealed Maintenance Free JB = Junction Box PB = Push Button TB = Terminal Box LCB = Local Control Board LCS = Local Control Station SPNDB = Short Circuit Protection Neutral Distribution Board TPNDB = Phase Three and Neutral Distribution Board CT = Current Transformer PT = Potential Converter SCIM = Squirrel Cage Induction Motor ACVS = Air-conditioning and Ventilation System FDA = Fire Detection & Alarm PCS = Pull Cord Switch ZSS = Zero Speed ​​Switch BSS = Belt Sway switch NO = Normally opened NC = Normally Closed TEFC = Total Enclosed Fan Cooled TESC = Totally Enclosed Surface Cooled GI Bus bar = Galvanized Iron Bus Bar For Farthing PLC = Programmable Logic Controller DCS = Distributed Control System MPI = Multi Point Interfac

tly * hunting during stop position EXAMPLE:-- * RADAR * computer . * roboytics * toys * CD\DVD player . NOTE--:: * dc servo motor operates more efficiently than AC servo motor. * it produces high torque at all speed . * it operates aat very low speed .

cylindrical of magnetically hard steel, with out winding and teeth * at strating this motor start with eddy current and hystresis both but at running condition runs only with hystresis loss * its rotor is made of smooth cylindrical hard chrome steel * it has no teeth and no winding on rotor * it is free from mechanical and magnetic vibration * it accelerate from rest to full speed at stant it operate at constant speed and performs noise less operation * its torque is directly proportional to hystresis loss APPLICATION --: * recording player * tap recorder and sound * timing devices * electrics clocks UNIVERSAL MOTOR --: * It works on both AC and DC supply * it is known as 1-phase series motor * its speed range lies between 3000 rpm -12000rpm * field winding and armature connected in series * its speed is inversaly proportional to load * direction of rotation can be changed either by changing field on armature winding * its speed is generally controlled by gair's train * it has preffered for high speed and high starting torque * torque pulsation is minimized by both rotor and load inertia * it has highest power to weight ratio * it has high starting torque and a varable speed characterstics * it run at dangerously high speed at no -load EXAMPLE * electric shaver * mixer * portable tools * drilling machine * table fans * sewing machine * vacuum cleaner * coffee grinder * food processor * repulsion motor is second priority used in vacuum cleaner after universal motor REPULSION MOTOR --: * it works on the combined principle of repulsion and induction * has highest starting torque * similar to 1-phase induction motor stator * rotor -two rotor winding are used one is squirrel cage and other usual dc winding connected to the commutator and a short circuit set of two brushes * it has lap and wave both type and winding its direction of rotation can be changed by changing position of brushes * the angle between brush axis and stator field axis must be equal to 45 degree * the position of short -circuit brrushes on the commutator the starting torque can be developed in the rotor * its field structurre has non-salient pole construction APPLICATION --: * hoist * machine in textile * printing process * high speed lift * electrical locomotive * film winding machine * vacuum cleaner STEPPER MOTOR -: * It gives step by step output, this step by step output also called as detent torque * it is a digital to analog conveter * it is widely used because of compatability with digital system *it has no brushes , winding and commutator on rotor * operation of stepper motor at high speed called slewings * it is a constant power device * it operates in a open loop that means has no feedback arrangement * it loose the torque at high rotational speed * it is more prone to error due to no feedback * it provides very low torque at higher speed * no vibration in stepper motor at standstill position * no encoder used * suitable for fluctuating load * tunning \gate adjustment not required * small size * cheaper * no hunting during stop position . APPLICATION --: * Small robotics * X-Y Plotter * digital watches * computer printing device * process control system SERVO MOTOR --: * A servo motor is a rotor actuator or linear actuator that allows for prices control of angular or linear position , velocity and acceleration. * it consist of electric motor, feedback device and electronic controller * there are mainly two types of servo motor AC servo motor DC servo motor * AC servo motor generally preferred for low power use. * DC servo motor preferred for high power use * it operates in a close loop that means has feedback arrangement * it maintains the torque at high rotational speed. * it is less prone to error because of feedback * it provides very high torque at higher speed * it has vibration at stand still position. * used an encoder * not suitable for fluctuating loads. * tunning\ gain adjustment required * big size * cos

GING IN 3-PHASE I.M --; CRAWLING --: * It comes due to harmonics developed in the motor * in crawling 3-phase induction motor has a tendancy to run at very low speed that means speed compred to synchronous speed * to reduce crawling skewed rotor is used * crawling can be reducing 5 and 7 harmonics , which can be done by using a chorded or short pitched winding COGGING --: * cogging occurs when the number of stator slots are equall to the number of rotor slots * also known as magnetic losking * in cogging motor refused to start * to reduce the cogging , the number of stator slots should never be equal to that of rotor slots CIRCLE DIAGRAM --: * it represents rotor currrent * frequency cant be determined * circle diagram used to find output power , input power losses , slip , torque , torque and efficiency of induction motor ADVANTAGE OF SKEWED ROTOR --: * reduce magnetic locking * reduce magnetic humming develop uniform torque * improve starting torque * reduces harmonics SQUIRREL CAGE INDUCTION MOTOR --: * DOL STARTER USED UP TO 5 H.P. * STAR DELTA STARTER USED UP TO 15 H.P. * AUTO TRASNFORMER USED UP TO ABOVE 15 H.P. * dol starter restricted to low h.p. motor dol starter takes largest starting current no controlling done for dol starter SPECIAL PURPOSE MOTOR --: 1) STEPPER MOTOR 2) SERVO MOTOR SOME FEATURES OF SINGLE PHASE INDUCTION MOTOR -- * not self started * closed slots used * power factor 0.6 lagging * have maximum 4 pole * phase displacement between starting and running winding is nearly 90 degree * known as fractional H.P. motor * operate on 1 -phase supply (230 v,50 hz) known as domestic motor * widely used in houses , offices, and controlling etc. *A single phase motor are truly a two -phase machines * aluminium bars are molded onn the slots and short -circuited at both ends with ring * the porpuse of starting windinng in a 1-phase I.M. is to produce rotating magnetic field in conjuction with the running winding SINGLE -PHASE INDUCTION MOTOR--: * not self started * requires 1-phase ac source * size is large * slip have two slips forward and back word slip * direction -by changing eighter main or auxillary winding * auxillary winding requires * closed slots * output power low * distributed winding * temperature- more temperature rise * cost is cheaper * known as domestic motor * application -: domestic use 3- phase induction motor * self starting * require 3-phase AC souce * small size * has only one slip forward slip * direction by changing any two phase sequence * auxiallry winding not requires * semi-closed slots * output power high * winding concentrated * temperature -low temperature rise * cost expensive * known as industrial motor * application --industrial use SHADED POLE 1-PHASE MOTOR --: * It rotes from unshaded to shaded * salint pole type stator * cage type rotor * efficiency is 5-35% * used where least torque is required its direction can't be changed * it is cheaper APPLICATION ---: hair dryer, toys, small fans ,electric clock, time phonograph RELUCTANCE MOTOR ---: * Stator- it has laminated construction made up of stamping * Rotor --- same as salient pole and not have any winding * at starting time this motor run at sub-synchronous speed and at steady state it runs at synchronous speed . * it is a motor which depends on reluctance torque for its operation * reluctance torque is the torque induced in an iron object in the presence of external magnetic field * it will align itself with the magnetic field to the magnetic circuit * the laminated constructionn keeps iron losses to minimum * the stamping are made up of material from silicon steel which minimize the hystresis losses APPLICATION -: * recording instrument * signaling device * timer * clock timer * synthetic fiber HYSTRESIS MOTOR --: * STATOR --- it's stator designed to produces a synchronously revolving field from a 1-phase supply * ROTOR--- * it consist of smooth

hase inducton motor ---: STATOR --- * it remains stationary * its shappe is hallow cylindrical * stator cre is made up of silicon steel * stator core is laminated to reduce eddy current loss * by using silicon steel 'hystresis losss' reduced 3-phase induction motor ---: ROTOR --- * it is rotating part * the rotor is separated from the stator by a smalll air- gap single cage rotor --: * starting torque is low * it has low rotor resistance and motor draws high starting current * the effective leakage reactance is low for same rating , cost is low . double cage rotor ---: * starting torque is high * the outer cage bars have high resistance and low reactance so motor draws low starting current * the effective leakage reactance is high * same rating coost is high due to double cage SQUIRREL CAGE INDUCTION MOTOR ---: * Rotor consist of bars which are shorted at the ends with the help of end ring * it is permanently shorted, external resistance can't be added * strting torque is low but running toque is high. * rotor resistance starter can't be used . speed control by rotor resistance is not possible. * due to simple construction the rtor are cheap. almost 95% induction uses this type of rotor EXAMPLE --: Drilling machine , water pump grinder ,Lathe machine; SLIPRING (PHASE WOUND INDUCTION MOTOR);- * rotor consist of a three phase winding. resistance can be added externally . * starting torque his high but running torque is low. * rotor resistance stsrter can be used . speed control by rotor resistance is possible. the rotor are very costly. * only 5% of induction motor are industry uses this type of rotor . EXAMPLE -:Lifts, Elevator , Cranes , Hoists , Compressor. 3 -phase induction motor ---: * uses distributed winding * loading type are electrical , magnetic and mechanical . * flux armature is 'Average flux'. * it is rotating machine Transformer --: * uses concenttrated winding * loading type are electrical and magnetic flux nature is maximum flux * it is a stationary device AC MOTOR ---: * ac motor can be single phase or three phase generates more heat comparatively in AC motor armature do not rotate while magnetic field continously rotates * AC motor recquires an effective statting equipment , like capacitor to start operation * average starting torque * simple to install * repairing of ac motors are not coastly . DC MOTOR ---: * All dc motor are single phase generates less heat hence less energy is washed * in dc motor the armature rotates while magnetic field does not rotate * dc motor do not require any external help to start operation * very high starting torque * complicated to install * repairing of dc motor are costly SOME FACT ABOUT 3 -PHASE INDUTION MOTOR ---: * It is a singly excited and self started motor * it is a transformer whose secondary is shorted * known as a rotating transformer * known as a synchronous motor because it followes synchronous speed (Ns) * it's starting torque is lower than dc shunt motor * equivalent circuit of 3-phase I.M. at starting is simillar to equivalent circuit of transformer when seconadary is short circuited WORKING OF 3-PHASE I.M.---: * 3-Phase supply is fed to 3-phase stator winding * rotating flux of constant value * rotating flux passes through air- gap and cuts rotor conductor * EMF Is induced in the rotor conductor rotor bar or conductor form a closed circuit so current flows through rotor conductor whose direction given by Lenz's law , is such as to oppose the couse of production * to reduce the relative speed the rotor start start running in the same direction as that of the flux and tries to catch up to the rotating flux, thus rotor of induction motor rotates NO LOAD TEST --: * it is similar to transformer's open circuit test * to calculate iron losses * to find shunt branch parameter BLOCK ROTOR TEST --: * it is similar to transformer's short circuit test * to calculate copper losses * to find series branch parameter 1a CRAWLING AND COG

SYNCHRONOUS MACHINE--: STATOR---- *Armature winding on stator and field wing done on rotor * laminated silicon steel used * concentrated winding used * open slots are used ROTOR--- ( SALIENT POLE TYPE )-------: * practically 12-20 poles are used * it has large diameter and small axial length * it has non - uniform air- gap * has more noise and mechanical losses. * it has low synchronizing capacity . * hunting occur here. * preferred for low speed alternators example-- used in hydro plants ( CYLINDRICAL POLE TYPE )--------: * Practically 2 poles used * it has a large axial length and small diameter * it has uniform air-gap * has low noise and mechanical losses. * has high synchronizing capacity * neglible hunting * preferred for high speed alternator example -- used in thermal power plant DC GENERATOR -- * It is a rotaing armatyre and stationary field * its size are generally large * has lower output ratings * has lower range of RPM . ALTERNATOR -- * it has rotating field and stationary armature * its size are generally small * has higher output rating * has higher rating range of rpm METHOD TO MAKE SYNCHRONOUS MOTOE SELF STARTED-- 3 -phase synchronous motor is not self started so, they needs following starting method 1) By external prime mover 2) By pony motor 3) By damper winding * damper winding used only for salient pole type rotor HUNTING -- * It is known as 'phase swing ' * hunting comes due to sudden change of load on a 3- phase synchronous motor by which it's speed oscillates about synchronous speed Ns and torque angle also oscillates at refrences , this phenomenon called as hunting COUSES OF HUNTING DUE TO --- * Sudden load variation on synchronous motor fault in stator winding * fault in supply system * fault in field supply system * harmonic in 3 -phase supply system EFFECT OF HUNTING -- * motor will be more heated * net work done decrease * Bearing may be damaged * stress developed at shaft ARMATURE REACTION SYNCHRONOUS MACHINE --- * armature reaction --- the effect of armature flux on main field flux is known as armature reaction * note --- when the armature is on no load , then very low value of armature current flows in the armature hence armature reaction can be neglected at no- loas 3 -phase induction motor ---- * self started * operates at lagging power factor only * runs always less than synchronous speed singly exited motor * used for mechanical loading * less efficient * it is cheaper synchronous motor -- * not self started * operates at leading lagging and unity power factor * run always at synchronous speed * doubly excited motor * used for power factor correction more efficient * it is costly DC MOTOR -- * it works on D.C. only * It run at various speed depending upon the kinds of load * it is small in construction * it has brush and commutator segment for commutation to convert D.C in A.C. * only one winding is enough for its operation synchronous motor ---- * it work on 3-phase AC and DC Both ( DC supply provided to rotor field winding) * it run at single speed that means at synchronous speed * comparatively large it construction no brush and commutator segment requires because of no conversion takes place. * need two winding and main winding and field winding for its operation voltage regulation in synchronous generator --: * it is the rise in voltage at the terminal when the load is reduced from full load rated value to zero value , when the speed and field current remains constant voltage regulation of alternator -: EMF method --: the value of voltage regulation measured in this greater than actual value known as 'pesiimistic method'. MMF method --: the value of voltage regulation measured in this method is less than actual value known as 'optimistic method' ZERO POWER FACTOR METHOD --: the value of voltage regulatioin measured in thids method is acceptable . tthat means most accurately known as 'potier triangle method' 3-p

pend on size of tank and supplied voltage's * transformer oil ---: it is used provide insulation and cooling purpose generally minerals oil and snthetic oil used as transformer oil dielectric strenght of transformer oil is 33kv\mm. TRANSFORMER OIL RECRUITMENT ---: high thermal conductivity low density high specific heat non - toxic good arc quenching properties * Transformer oil should have ---: high flash point low viscosity low pour point low volatility Flash point ----: it is the minjimum temperature at which transformer oil begins to convert into gases flash poitnt --140 degree celcius Pour point ---: it is the minimum temperature at which transformer oil freezed pour point --30 to 40 %. Conservator tank ---: conservator tank is used to take up construction and expansion of transformer oil'. it is a partially filled with temperature oil' Breather ---: when the load on the transformer decreased than transformer tanks breath , so breather is used t filter out the moisture content from the air * breather is used to arrest the flow of moisture when outside entters in the transformer it is connected with conservator tank silica gel is used in brether to absorb the moisture content silica gel ; when new ;'blue' in colour when wet ; 'pink in colour Buchholz relay --: it is used to protect transformer from intrnal faults lke- short -circuit , inter turns ,faults and internal failure * it is a gas actuated relay it is connected between main tank and conservator tank it is used for transformer rating more than 500 kva used only for oil filled transformer Oil level indicator --: it is used to indicate and to monitor the oil level in conservator tank known as magnetic oil level gauge (MOG) TAP CHANGER ---: The main purpose of a tap changer is to regulate the output voltage of a transformer * Tap changer always connected to H.V. side because of low current so less sparking occurs Requirement of tap changer---: to counter the input supply voltage changes on load to supply a desired voltage to the load Radiator tubes for cooling ---: radiator tubes are used in transformer for the cooling purpose by using radiator tubes, increasing the heat dissipation are thus cooling phenomena performed transformer IDEAL TRANSFORMER there is no losses there is no leakage flux voltage regulation is zero efficiency ia 100 % core permeability is infinite which corespond to zero core reluctance it is impossible to construct an ideal transformer PRATICAL TRANSFORMER There are copper and core losses there is small amount of leakage flux voltage regulation is never zero efficiency is 95 to 99 % core permeability is is finite all constructed transformer are pratical transformer HUMMING NOISE ---: noise in transformer is called 'humming noise' humming comes due to magnetostriction ALL DAY EFFICIENCY--: it is used for distribution transformer all day efficiency =energy output in kwh for 24 hr\energy input in kwh for 24 hr Air core transformer --: if core of transformer is replaced by air then transformer is called air core transformer * area under B-H curve is zero for air core transformer B-H curve is linear for aair -core transformer Isolation transformer --: it is used to isoplate the circuit has turn ratio 1:1. CORE LOSSES --: it is a constant losses. coused by the alternating magnetic flux in the core COPPER LOSSES --: It is a variablr losses coused due to the winding resistance EDDY CURRENT LOSS--: It occurs because of the relative motion between the core and the magnetic flux by making the core of thin lamination HYSTRESSIS LOSS--: It occurs because of the reversal of the magnetism by using silicon steel material OPEN CIRCUIT TEST --; To find core losses to find shunt branch parameter its performed at L.V. side at rated voltage and rated frequency instrument are connected at L.V side SHORT CCIRCUIT TEST--: To find copper losses to find series branch its peerformed at H.V. side at reduced voltage 5%-10 % , rated current and rated frequqncy instrument a

es not change power and frequency because both remains constant there is no rotating part in transformer hence friction and windage losses are zero that's why * efficiency of transformer is maximum among all the machine there are generally two types of transformer 1-: core type 2--:shell type CORE TYPE -: Core is surrounded by winding Cylindrical type winding used Has only one magnetic flux path contains two limb and two yoke core has only one window prefferred for high rating of large transformer easy to repair has more leakage flux hence more losses so less efficiency has less mechanical protection of coil requires more conductor material called series magnetic circuit total magnetic flux flows through the entires core its outer winding has H.V. (high voltage) SHELL TYPE ---: Winding is surrounded by core sanwich type winding used have two magnetic flux path contains three limb and two yke core has two windows preffered for low rating of small transformer difficult to repair has less leakage flux hence less losses so more efficiency has better mechanical protection to coil equires less conductor material called parallel magnetic circuit there are two magnetic paths so the total flux flows through the central limb its outer winding has L.V. (low voltage ) POWER TRANSFORMER -: Transformer more power voltage may be step up or step down indoor located used for transmission and generating stations load fluctuation are very low its capacity is in MVA designed for maximum efficiency at 100% load designed for full load efficiency for a higher value of flux density tap changer not uses DISTRIBUTION TRANSFORMER -: Transformer low power voltage is always step down outdoor located used to distribute the power near to load load fluctuation are very large comparison to power transformer its capacity is in KVA designed for maximum effiency at 50 to 75% load. designed for about half load effiecency and for a low value of flux density tap hanger uses only for distribution TRANSFORMER CLASSIFICATION-: Based on construction -- core type , shell type , berry type. Based on rating or utility ---- power transformer, distribution transformer. Based on cooling system ---- air cooled, oil cooled ,self cooled Based on the voltage level ---- step-up transformer , step-down transformer. Based on the phase ---- single phase , three phase Based on winding ---- single winding (auto-transformer ) two winding (core or shell type ) Based on measurement instrument --- current transformer (C.T.). potential transformer (P.T.). Based on connection---- star delta ,star star , delta star, delta delta, v-v connection , t-t connection * C.T. is a step up transformer while P.T. is a step down transformer. Components of a transformer -: winding ---In transformer there are two winding, used which are primary and secondary winding the primary winding is the coil which draws power from the source and secondary winding is the coil which delivers the power to the load * H.V Winding ---:it has a large number of turns of thin wire . * L.V. Winding ---: it has a less number of thick wire * Iron core ---: in the transformer iron core is used to facilitate low reluctance path for the flux linkage between the primary and seconadary winding * in large transformer generally soft iron core or CRGO (cold rolled grain oriented steel) is used to reducing the hustresis losses . core is also laminated to reduce eddy current losses. * transformer tank --: it is also named as transformer body which iss made of steel metal (mild steel )with a high thickness. it is used to protect , hold the bushing and cooling purpose * Yoke ---: it is the horizontalposition of thee core is known as yoke * Limb---: it is the vertical position of the core which contains winding * bushing ---: in the transformer , HV ( high voltage ) and low voltage line terminal are taken out from tank thriough bushing * bushing provide a very effective insulation between line conductor and tank or earth . Bushing size de

tating inverter * According to voltage and current requirement armature winding can be connected are - Lap winding wave winding LAP WINDING --: * it is a complete winding so, mechanically balanced * number of paralell path ids equal to number of pole * equalizer ring used to stop circulating current * number of brushes are equal to number of parallel path * Lap winding used for low voltage and hhigh current WAVE WINDING --: * It is in complete winding so, mechanically unbalanced. To make it balance , a 'dummy coil' is used. * number of paralell path is always equal to two . * winding where 'dummmy coal is used called forced winding'. * Number of brushes are always two because of to parallel pat. * wave winding useed dfor high voltage and low cuurrent BRUSHES ---: * It is a stationary prart of DC machine. * brushes are made of carbon * width of carbon brushes should be equal to the width of 2 to 3 commutator segment * carbon brushes provide sejlf lubrication also * copper brushes are preferred for low voltage and high current. * for DC generator brushes are used to provide DC current to commutator from dc supply source. * Graphite brushes are preferred for high voltage low current * for DC generator brushes are used to recieve DC current from commutator. STATOR WORK --: * To provide magnetic path * to protect inner parts from outer atmospheric condition * to have pole core DC GENERATOR --:: * It converts mechanical energy into electrical energy * direction of induced emf is find out by fleming's right hand rule * it's rating is in 'KW' ( killo - watt). * in dc generator voltage controlled phenomena is use. * magnetic neutral axis rotates in the direction of rotation of generator. * polarity of interpole is next main pole ahead to the diraction of rotation * in dc generator armature reaction affects generated voltage * in DC generator maxximum flux occur's under trailing pole tip' DC MOTOR -: * It converts electrical energy into mechanical energy * Direction of rotation is find out by fleming's left hand rule * Its rating is an 'HP' * In DC motor 'speed controlled ' phenomena is uses . * Magnetic neutral axis rotates in the opposite direction of the rotation. * in DC motor armature reaction afects torque * polarity of interpole is the next main pole behind to the direction of rotation * In DC motor mazimum flux occur 'undrleading pole tip' TYPE OF STARTER --: TWO - POINT STARTER -: ONLY FOR DC SERIES MOTOR THREE POINT STARTER -: FOR DC SHUNT SHUNT MOTOR THREE POINT STARTOR -: FOR DC SHUNT MOTOR AND DC COMPOUND MOTOR DC generator application -: DC shunt generator ------- battery charger power supply anexciter for electro plating used where constant voltage is required DC series generator appllication-------- used as booster as a supply for arc lamp Used for series are lightning DC motor is application -: DC SHUNT MOTOR ----- speed is fairly constant and require medium starting torque lathe machine milling machine machine tool blower and fans drilling machine centrifugal and reciprocaating pumps DC SERIES MOTOR--: used where high starting torque requires,no-load condition is dangerous at variable speed Cranes Hoists Elevator Trolleys Conveyor Electric locomotive DC COMPOUND GENERATOR ---: 1--: differential compound generator ---: used to supply dc welding machine 2--: level compound generator ---: used to supply power for officer etc. 3--over compound generator ---: used to compensate the voltage drop in feeder ARMATURE REACTION --: the effect of armature flux on the main field flux is known as armature reaction. Dc compound motor ---: cumulative comppound motor ------ elevator punches shears rolling mill Differential commpound motor --- not suitable for any pratical application TRANSFORMER ----: a transformer is a static device which transformer power one side to other side without changing the frequency wiyh the help of Faraday law's of electromagnetic induction. NOTE --:A Transformer changes voltage and current and do

SOME IMPORTANT POINT ARE RELATED FOR JE AND AE EXAM ---: * generator are used in arc welding -- differential compound generator * commutator in a dc machine is --to change AC voltage to DC Voltage * dc shunt generated is -- self excited * armature reaction effect is more in -- field weakening method. * DC generator can be termed as -- rotating amplifier * duynamic braking ----shunt motor, series motor , compound motor . * compound motor -- fly wheel drive * shunt generator -- battery charging * series generator -- poorest voltage regulation * commulative compound generator --best voltage regulator * normal value of the armature resistance of a dc motor is-- 0.5 * the DC motor having the high staring torque is -- series motor * lamination of core are generally made of silicon steel * field coil of DC generator are usually -- made of copper * dynamic braking is generally used with DC motor * field copper losses are constant in DC motor -- shunt * regenrative braking the motor energy is -- returned to supply mains * interpole is winding is connected --series with armature * Armature of DC generator is laminated is -- reduce eddy current loss. * field coil of Dc generator are usually made of -- copper * dummy coil are used -- mechanical balance * DC shunt generator has --- slightly drooping curve * E.M.F. of a DC generator depends on-- speed * commutator in a dc machine to change in alternating current into direct current * generator are used in arc welding -- differential compound generator * dc motor are shape of main flux distributon - flat tapped or trappezoidal * Dynamic braking is very effective if the dc motor --is separately exited * simplest forms of a motor controller is --toggle switch * E.M.F. induced in the D.C. generator armature winding --A.C. * D.C Machine winding are -- full pitched * variable loss in a D.C shunt machine is -- armature copper loss * the load is increase the speed of a D.C. motor will -- reduce slightly . * A Transformer has no friction amnd windage losses * A Synchronous machine develop synchronous torque only at -- synchronous speed * hystresis motor and reluctance motor are -- synchronous motor * repulsion motor is an induction motor * synchronous motor is a doubly excited motor * synchronous machine working at --leading power factor * sumpner test is conducted on transformer -- temperature * maximum efficiency of distributed transformer --50 % full load * principal o transformer -- mutual inductance * transformer rating KVA * Shell type transformer is known as -- 1phase transformer * simple porcelain bushing are used for transformer --11KV * SCOTT CONNECTION --TWO -PHASE TO THREE -PHASE OR THREE-PHASE TO TWO -PHASE . *a trnsformer tank usually made up -- mild steel DC MACHINE -: Constructiion of DC machine ------: same for both DC Machine and DC Generator STATOR --: it is the outer part of dc machine it contains pole, core has pole shoe which are laminated pole core contains field winding. pole shoe are used for spread out the flux in the air gap uniformely. ROTOR --: It is the inner part of DC machine it has armature core and armature winding armature core made up of laminated steel armature winding done in armature core slots armature is keyed to the shaft * Yoke of large DC machine steel and for small DC machine cast iron is used COMMUTOR -: * It is a rotaing part of DC machine it lies rotor shaft it mantain electrical connection between rotating rotor and stationary brushes it is a made up of a hard drawn copper and 'mia insulation' provided to inssulate the commutator segment Due to the limitation of commutator , DC generator are not usually designed beyond 650V. In DC machine, nmber of commutator segment are equal to th enumber of armature coil, the main function of commutator in a DC machine is to change AC voltage into DC voltage and vice -versa for Dc generator commutator is known as mechanical rectifier or rotating rectifier . for DC motor commutator is known as 'mechanical inverter or ro

* thermal type relay work on -: both A.C. and D.C. supply * Static type relay work on -: both A.C and D.C. supply * HRC fuse provide best protection against -: short circuit * value of fusing factor is always -: more than one * Fuse work on joule law of heating * Fuse is a protective device * Gas relay is operated by -: gas pressure * Rating of fuse wire is always -: ampere * Value of fusing factor -: always more than one * full name of TPICS -:Triple ppole iron clad switch . * potential transformer is a -: step down transformer * current transformer is a -: step up transformer Relay is a sensing element * fuse are used for -: stopping over current Indoor * switch gear is generally used for voltage upto 66kv * Oil switch used for -: high voltage and high current * Relay is used for give command to circuit breaker * fault level is expreessed in MVA\ KVA * most dangerous fault -: three phase

circuit FUSE ELEMENT OR FUSE WIRE -: it is that part of the fuse device which melt when an excessive current flows in the circuit and thus isolates and the faulty deice from the supply circuit. MINIMUM FUSING CURRENT -: It is a value of current corresponding to a chosen value of time indicated on a time \current work which is it self obtained from prescribed testing condition FUSE RATING -: it is the value of current which flows through the element when fuse does mnot melt Prospective current -: R.M.S. in nature appear in circuit when a short circuit occurs Melting time or pre-arcing time -: the time taken from the instant the current that causes a break in the fuse wire start flowing , to the instant the arc in initiated . ARCING TIME -: The time taken from the instant of arc initiation to the instant of arc being extinguished . HRC FUSE -: HIGH RUPTURING CAPACITY FUSE. Construction -: the hrc fuse consists of a ceramic body usually of steatite, pure silver element, clean silica quartz, asbestos washers, porcelain plug ,brass end-caps and copper tags HRC fuse operation -: when hrc fuse operates , the element absorb energy from the circuit and heats until it melts protection of bus bar and transmission line -: bus bar fault ---- failure of insulation earth fault failure of circuit breaker flash over earth quake and mechanical damage PROTECTION -: Frame leakage protection of bus bars circulating current protection bus bars high impedance differential protection of bus bars feeder protection -: feeder = transmission line &distribution circuit various method ---- 1) over current protection 2) distance protection 3) pilot relaying protection ELCB -: ( EARTH LEAKAGE CIRCUIT BREAKER ) ZSCT-: ( ZERO SEQUENCE CURRENT TRANSFORMER ) SOME ALL MIX POINT ---: * open circuit has resistance -: infinite * short circuit has resistance -: zero * most common type of foult is -;1 phase to ground * induction type relay are called -; magnitude relay * frequency of symmetrical fault -: 5%. * assemtrical fault frequency -:95 % * relay is design -: max. torque function ratio * cable sheath are used -: for cross bonding * resistance grounding is used -: 33 kv to 132 kv * bus bar is manufacturer by -; aluminium * bus bar is rated by -: current voltage and frequency and short circuit current * close type reactor used -; upto 33 kv * lightning are -: lightning of clouds * full name of S.W.R. -: standing wave ratio * surge are -: high voltage wave * osciillator -:high frquency wave * IDMT relay -: protection of distribution * transformer IDMT relay -: for protection of internal short circuit . * thermal relay is used in motor -:over load protection * speed cotrolling in shaded pole relay is used -: from unshaded pole to shaded pole from of back up protection is used -: fuse * shaded pole type relay is mad by aluminium * full name of P.S.M.-:pulse with modulation * induction type relay work on only A.C. Supply * value of pick up current -:CT secondary value current setting * thresold value of the actuating quantity above which the relay will operate is called -pick up value. * magnetic relay is -: instantaneous relay * R.M.S.value of actuating quantity which relay rest is called -: pick up value * full name of ITLR -: inverse time lag relay * full name of D.T.L.R.-: definite time lag relay * relay operate when voltage exceed preset value -; over current. * An isolator operate under -; no load condition isolator are capable of breaking -: charging curent. * Relay is conneced between -: main electric circuit and circuit breaker. * Relay is operated device sensational type electrical device * relay is an electro-mechanical switch. * Relay perform the function -:fault detection outdoor isolator are used -: above 33kv * switch is used to below 1kv isolator is used -: 1kv . * Indoor isolator are used -: up to 33 kv * Fuse is never inserted in -: neutral wire * fuse is inserted in -: phase wire . * Induction type relay work on -: only A.C. supply * Static relay -: ther is no moving parts

restrain over current relay or voltage restrain non-directional relay APPLICATION -: medium transmission line Reactance relay --: the reactance relay is an over current relay with the directional torque the directional element is no designed that the maximum torque angle is 90 degree CONSTRUCTION --induction cup type Other name is a --Directional restrain over current relay USE--- Short transmission line mho relay\admittance relay --: the mho relay is made inherently directional by adding a voltage winding called polarizing winding .this relay work on the measurement of admittance CONSTRUCTION --INDUCTION CUP TYPE STRUCTURE OTHER NAME -:voltage restrained directional relay USE-: long transmission line offset mho relay -: in the off set mho relay, only a fraction of the C.T. output current is injected into the restrain circuit this fraction is 'n' which is the less than the 1 . the quantities which are compared for the operation. APPLICATION -: 1) operation for the close -up fault 2) bush bar zone back up protection 3) carrier blocking protection scheme 4) blocking of power swing Classification of distance relay --: 1) definite distance relay -Definite distance type impedance relay 2) distance time relay-distance time impedance relay ADVANTAGE OF DISTANCE RELAY-: 1) gives faster operation 2) simpler to co-ordinate 3) les effect of foult level and foult current magnitude 4) permits high line loading 5) with the need at readjustment, permanet setting can be done APPLICATION-: THREE PHASE FAULTS PHASSE TO EARTH FAULTS PHASE TO PHASE FAULTS advantage of over current relay -: very high speed of operation fast reset directional feature may be present FEATURE OF DIRECTIONAL RELAY -: high speed of operation high sensitivity ability to operate at low voltage adequate short time thermal relay CIRCUIT BREAKER ----: 'A circuit breaker can make or break a circuit either manually or automatically under no load, or short circuit condition ." IMPORTANT TERMS RELATED WITH CIRCUIT BREAKER -: recovery voltage --it is the voltage having normal power frequency which appears after the transient voltage. it is RMS in nature. effect of reactance drop on recovery voltage effect of armature reaction on recovery voltage AC CIRCUIT BREAKING --: current is reduced to zero twice in every cycle. arc current can be reduced to zero when volage is redued to zero C.B. can have higher rating for same capacity. arc current naturally reduced to zero . smaller voltage appears across C.B. contacts during arc. interruption DC CIRCUIT BREAKING --: Current is never reduced to zero arc is continued and arc current is difficult to reduce unless the contacts arc widely open. the C.B. can have lesser rating for same capacity due to larger arc currents Arc currents is formed to zero larger voltage appears VACUUM CIRCUIT BREAKER -: Arc quenching medium vacuum Advantage - compact in size and have longer life with stand lightning surges low arc energy low inertia DISADVANTAGE -- Erosion of material currrent chopping because of low pressure Application --: voltage range 22kv-66kv capacity 66kv to 100 mva best operated -36 kv Oil circuit braker -- 1) bulk oil circuit breaker 2) minimum oil circuit breaker ISOLATOR -: Break the circuit under no load codition isolator is peresent at both side of C.B. isolator are used on transmission line are capablr of breaking =charging current type of isolator -: 1) single break type 2) double break type 3) penta graph type isolator Isolator -: isolate a circuit after the decay of current in the circuit it is only a switching device no mechanism for arc extinction operated under no load condition Circuit breaker -: break a circuit carrying current under faulty condition and make and break the current under normal operating condition switching as well as protective deevice provides medium for arc extinction operated under load condition FUSE-; fuse is a device used in circuit for protecting electrical equipment against over load and short

ver current relay . 4-: for the diffirential protection 5-: used as auxiliary in the contacts system of protective relaying scheme Induction type relay---- the induction type relays are also called magnitude relays. These relays work on the principle of the induction motor or an energy meter BUCHHOLZ RELAY (GAS ACTUATED RELAY)--- Buchholz relay is a gas operated relay used for the protection of oil immersed transformer against all the type of internal foult. it is also known as incipient foult relay oil decomposes - generating the hydrogen gas buchholz relay are provided for the transformer having rating above 500kva ADVANTAGE ---- buchholz relay gives an indication of the fouult at very early stage, by anticipating the foult and operating the alarm circuit it is the simplest protection in case of transformer LIMITATION ---- Used only for oil immersed transormer having conservator tank only foults below oil level are detected setting of the mercury switches can not be kept too sensitive other wise the relays can operate due to bubbles, vibration, earth quake,mechanical shocks the relay is slo to operate having minimum operating time of 0.1 sconds and average time of 0.2 seconds APPLICATION ---- local overheating bushing puncture entrance of air bubles in oil short circuit lamination bad or loose electrical contacts short circuit between phases loss of oil and reduction in oil level due to leakage Introduction to over current relay--- the over current relays are classified depending upon the time of operation.. Instantaneous over current relays ---- no internal time delay provided the operating time is less than 0.01seconds these relay are effective only when the impedence between the relay and the source Zs is every small compared to the impedance of the protected sction Ze. Inverse definite time relay ---- if the saturation occurs at a very early stage than the time of operation almost remains same over the entire working range of relays. this is called definite time. Inverse definite minimum time relay (IDMT).--- The core saturation current slightly higher than the pick up value of the current this is called inverse definite. Very inverse relays --- The core saturation occurs at a further later stage than the inverse nature of characterstics continues for longer range and tank the shape indicated by the curve C. This is called very inverse time charactersics After saturaion, the curve tends to definite time . extremely inverse relays-- in such relay the saturation occurs at very later stage and the curve has an inverse nature for almost entire working range Non- directional induction type over current relay --- It is also called earth leakage induction type relays its constrution similar to a watt hour meter with slight modificataion DIRECTIONAL POWER RELAY --- USE---providing the reverse power protection to synchronous machine Directional induction type over current relays---- the directional power relay is not suitable to use as a protective relay under short circuit condition hence in practice directional induction type over current relay used this relay operates almost independent of system voltage and power factor Use -- two relay element mounted on a common case these element are -- 1) directional element which is directional power relay 2) non directional element which is non- directional over current relay Relay use as a comparator --- mays relays operate based on the resultant of the comparison of the two quantities DIFFERENTIAL RELAY ---- A differential relay is defined as the relay that operates when the phasor difference two or more similar electrical quantities exceeds a predetermined values. types of differential relay --- 1) current diffirential relays 2) biased beam relay or percentage differential relay 3) voltage balance differential relay . DISTANCE RELAY -: In distance relay the operation is dependent on the ratio of the voltage and current which is expressed in terms of an impedance impedance relay other name is Voltage

Over head line ---------------50% faults switch gear-------------------15%faults transformer ------------------12% faults cables ------------------------10 %faults miscellaneous----------------8% faults conntrol equipment----------3% faults CTs and PTs-------------------2% faults SOME FOLLOWING FEATURES OF SWITCH GEAR Certain discrimination Provide manual and automatic control Realiability Quick response TERMINOLOGY IN SWITCH GEAR Proteective zone dead spot or blind spot in a power system primary and backup pretection 1-- Primarry protection 2--Back up protection "The primary protection is the first line of defense and is responsible to protect all the power system element from all the type of fault." Main protection can fail due to many reason like -: Failure circuit breaker failure in protective relays failure in tripping circuit failure in DC tripping voltage loss of voltage or current supply to the relay METHOD OF BACK-UP PROTECTION -- Relay back up protection Breaker back up protection Remote back up protection Centrally co-ordinate back up protection SYMMMETRICAL FAULTS The symmetrical fault gives rise to equal fault currents in all th elines example -:L-L-L fault , L-L-L-G fault UNSYMMETRICAL FAULT A fault in a power system which gives unsymmetrical current in the three lines with un equal displacement is called unsymmetrical fault . example-:L-G fault ,L-L fault , L-L-G fault open circuit fault EFFECT OF FAULT due to heavy fault current which can damage the power system equipment The heavy currents produces over heating and high mechanical stresses. If the fault persists for longer time then fire may spread to other parts of the system Weakening of insulation due to over heating Due to unbalanced currents and voltage due to fault generator may loss synchronism Reducing the reliability of the system RELAY---- A' relay is an electrically operated switch it consists of a set of input terminal forr a single or multiple control. signals, and a set of operating contact terimanal CLASSIFICATION OF PROTECTING RELAY---: 1-: Electromagnetic attraction type relay------------ A) solenoid type B) attracted armature type C) Balanced beam type 2-:Induction tye relay A) Induction disc type B) Induction cup type 3-: Directional type relay A) Reverse current type B) Reverse power type 4-: Relay based on timing A) Instantaneous type B) Definite time lag typ e C) Inverse time lag type 5-: Distance type relay A) impedance type B) reactance type C) admittance type 6-: Differential type relay A) Current differential type B) Voltage differential type 7-: Other type of relay A) Under voltage , current , power relay B) over voltage , current ,power relay C) thermal relay D) rectifier relay E) parmanent magnet moving coil type relay F) static relay G) gas operated relay * Relay armature pulsates at double frequency. This caouse the relay to hum and produces a noise. It may couse damage to the relay contacts yo overcome this difficulty using shading in a relay Advantage of electromagnetic relays-- 1-: Can be uesd for both AC and DC 2-: They have fast operation and fast reset. 3-: These are almost Instantaneous 4-: High operating speed with operating time (ms) 5-: the pick up can be as high as 90-95%for DC operation and 60%- 90%. for the AC operation disadvantage ---- 1-; the directional features is absent 2-: the working can be affected by the transients. 3-: due to the presence of moving parts the response is not very quick due to inertia of the parts, compared to modern statics relay 4-: Due to high burden on current and potential transformer the size is large and cost is high 5-: life is less and high failure rate compared to static relay Application of electromagnetic relay 1-: the protection of various AC and DC equipments 2-: over \under currents and voltage protection of various AC and dc equpments 3-: in the definite time lag over currents and earth and foult protection along with definite time lag o