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KRL TEST Ques

Q1- energy stored in an inductor? (1/2 LI2)Q2-buccholz relay is used for? large internal faults, overcurrent protection, any of them.....(flux saturation)Q3- breathing in transformer is used for.......Q4- wattmeter is used to measure ? active* , reactive, real, total power....Q5- if shunt resistance is increased in parrallel with galvalnometer, thencurrent sensitivity decreases, current sensitivity increases, deflection torque increases, resistance increases.....Q6- jogging is used for......breaking, motor running and then stopping, loading motor in steps*....Q7-emf of dc generator isEg= 4.44 fN F, Eg=120f/P, Eg= PFNZ/60A*Q8- in bus var protection, differential bus bar scheme has a series resistance, it is due tolimit voltage that can damage relay,dissipate power across the resistance, for proper functioning of relay, All of themQ9-for parallel function of 2 transformers, it must havesame polarity*, same capacity, same voltage ratio, same efficiencyQ10-form factor isrms/avg*, peak/rms, avg/rms........

• Q11- output of auto-transformer isinput(1-N2/N1) , output (1-N2/N1), output (1-N1/N2)Q12- power of 2 phase sine signal isVIcos F/2, VIcos F, sqrt (2)VIcos FQ13- speed of induction motor isNs, 0.5Ns, sNs, Ns(1-s)*Q14-megnatic field of straight line conductor isNIµ/(2*pi*r) , NIµ/ l(length), third option i don't know

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Q15-if core loss =600W, copper loss =900W, then at which percent load , efficiency will be max75%, 100%, 50%, 25%Q16- for microwave frequency, which core of transformer is usedcarbon, silicon steel, ferrite, ferromagneticQ17-if frequency increases, hysterisis loss willincrease, decrease, unchangedQ18- ohm's law is not applicable onhigh current, low resistance, high power, semi conductorsQ19- at resonance, the angle is45 degree, 90 degrees, 180 degrees, 0 degree*Q20- pf of transformer isalways leading, lagging, 0.8, depends on the nature of load*

Q21- pf of synchronous generator is dependent onload, angular speed, armature loss, core lossQ22- efficiency of distribution transformer is maximum atno load, 50% load*, 75% load, full loadQ23- magnetising component of the transformer isalways lagging*, leading, any of theseQ24- total current in unbalanced phase isalgebraic sum of Ia+Ib+Ic, vector sum of Ia+Ib+Ic*, zero.Q25- capacitor is always designed forpeak voltage*, average voltage, rms voltageQ26- spark is produced due tohigh resistance, high inductance, high power, allQ27- for 6 pole sync generator, electrical degrees in one revolution is equal to degrees360,720, 1080, 2160Q28- max efficiency of syn generator is when which configuration is usedsalient poles, non-salient poles, any of theseQ29- if 1000W heater is in series with 60 W lamp, now 100W lamp is connected with heater, what will be the effectheater output will decrease

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heater output will increaseheater output remains constantQ30-if 220 V dc series motor is given 220 V ac, then what will happen?motor will burn, it will not start, it will work smoothly, it will function but at low power*Q31- Ac is preffered over dc due toeasy transformation*, low losses in long transmission lines, high powerQ32- if voltage is doubled in the transmission line, then the conductor material used will behalved*, one fourth, doubled, four timesQ33- if P=1000W, voltage is 200 V, then resistance will be20 ohm, 40 ohm, 400 ohm, 4000 ohmQ34- which will have the least value of resistance220V1000W , 220V 500W , 115 V 1000W, 115V 500WQ35- if resistance of tungsten is 10 times the cold resistance; if 200 V is applied and P=1000W then resistance of cold resistance will beQ36- 3 phase induction motor has f=50Hz, 220V, 200W and s(Slip) = 3%, then rotor frequency will be1.5 Hz, 2 Hz, 4Hz, 3HzQ37-P=200hp,200V,50Hz, 3-phase induction motor, full load current will be( i don't know the options)Q38- in 3-phase delta configuration, I=40A, what will be current in Y configuration40A, 28A, 21A, 55AQ38- core loss can be taken out by testshort cct test, open cct test, ( 2 other tests i didn't study in engineering)Q39- if load on the transformer changes, thencore loss is unchanged, copper loss changes, core loss changes

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Q40-jogging is used due toBreaking, step by step motor speeding*, ( 2 other options)

(note: check all answer by yourself, some of ‘em may not be correct)