KRL TEST Ques
Q1- energy stored in an inductor? (1/2 LI 2) Q2-buccholz relay is used for? large internal faults, overcurrent protection, p rotection, any of them.....(flux saturation) s aturation) 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, then current 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 is Eg= 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 to limit voltage that can damage relay,dissipate power across the resistance, for proper functioning of relay, All of them Q9-for parallel function of 2 transformers, it must have same polarity*, same capacity, same voltage ratio, same efficiency Q10-form factor is rms/avg*, peak/rms, avg/rms........ • Q11- output of auto-transformer is input(1-N2/N1) , output (1-N2/N1), output (1-N1/N2) Q12- power of 2 phase sine signal is VIcos F/2, VIcos F, sqrt (2)VIcos (2)VIcos F Q13- speed of induction motor is Ns, 0.5Ns, sNs, Ns(1-s)* Q14-megnatic field of straight line conductor is NIµ/(2*pi*r) , NIµ/ l(length), third option i don't know Q15-if core loss =600W, copper loss =900W, then at which percent load , efficiency will be max
Prepred by: waqas ur rehman.
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75%, 100%, 50%, 25% Q16- for microwave frequency, which core of transformer is used carbon, silicon steel, ferrite, ferromagnetic Q17-if frequency increases, hysterisis loss will increase, decrease, unchanged Q18- ohm's law is not applicable on high current, low resistance, high power, semi conductors Q19- at resonance, the angle is 45 degree, 90 degrees, 180 degrees, 0 degree* Q20- pf of transformer is always leading, lagging, 0.8, depends on the nature of load* Q21- pf of synchronous generator is dependent on load, angular speed, armature loss, core loss Q22- efficiency of distribution transformer is maximum at no load, 50% load*, 75% load, full load Q23- magnetising component of the transformer is always lagging*, leading, any of these Q24- total current in unbalanced phase is algebraic sum of Ia+Ib+Ic, vector sum of Ia+Ib+Ic*, zero. Q25- capacitor is always designed for peak voltage*, average voltage, rms voltage Q26- spark is produced due to high resistance, high inductance, high power, all Q27- for 6 pole sync generator, electrical degrees in one revolution is equal to degrees 360,720, 1080, 2160 Q28- max efficiency of syn generator is when which configuration is used salient poles, non-salient poles, any of these Q29- if 1000W heater is in series with 60 W lamp, now 100W lamp is connected with heater, what will be the effect heater output will decrease heater output will increase heater output remains constant
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Q30-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 to easy transformation*, low losses in long transmission lines, high power Q32- if voltage is doubled in the transmission line, then the conductor material used will be halved*, one fourth, doubled, four times Q33- if P=1000W, voltage is 200 V, then resistance will be 20 ohm, 40 ohm, 400 ohm, 4000 ohm Q34- which will have the least value of resistance 220V1000W , 220V 500W , 115 V 1000W, 115V 500W Q35- if resistance of tungsten is 10 times the cold resistance; if 200 V is applied and P=1000W then resistance of cold resistance will be Q36- 3 phase induction motor has f=50Hz, 220V, 200W and s(Slip) = 3%, then rotor frequency will be 1.5 Hz, 2 Hz, 4Hz, 3Hz Q37-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 configuration 40A, 28A, 21A, 55A Q38- core loss can be taken out by test short cct test, open cct test, ( 2 other tests i didn't study in engineering) Q39- if load on the transformer changes, then core loss is unchanged, copper loss changes, core loss changes Q40-jogging is used due to Breaking, step by step motor speeding*, ( 2 other options)
(note: check all answer by yourself, some of ‘em may not be correct)
Prepred by: waqas ur rehman.
[email protected]
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Prepred by: waqas ur rehman.
[email protected]
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