SUPARCO test Ques:
1- Which of the following effects dominate in long transmission lines? (skin, feranti*, compton) 2- disruptive critical voltage for air is? (10kv/cm, 20kv/cm, 30kv/cm*, 40kv/cm) 3- at 11kv which of the following insulators used? (pin type*, suspension, string, none of above) 4- surge impedance of HV transmission line has a value of ? (20, 100, 300*, 400, 500) ans Zo is of order of 250-350 ohm 5- Xtic impedance relation ship with T/L length? ans independant of Length 6- loss angle ? 7- shielding angle for overhead transmission lines? (15, 30*, 45, 60) 8- if system freq increased from 50 to 53 hz, which of the following will be affected most? (power transformer*, alternator, turbine, all) 9- effect on capacity of T/L line if freq changed from 50 to 60hz? 10- no of discs used for 220 kv? (10, 15*, 20) 11- spacing between bundle conductors in T/L line? (20, 30, 60, 80) 12- GMD, GMR 13- 2 to 3 per unit questions (memorise formulae) 14- relationshhip between inductance and GMD, GMR? 15- HVDC used for ? (Long distances*, short distances, medium) 16- non uniform dist of current ? (ferranti, skin, proximity*) 17- conductor inner flux relation with frequency? 18- marginally stable system? (having real part of roots= zero) 19-
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20- load factor numerical 21- capacity factor num 22- load curve num 22- running cost base ascending order of hydel, thermal, nuclear, diesel 23- max Transmission V in pak? 500kv 24- turbine efficiency can be increased by (regenerating, reheating, intercooling, all) 25- which of the following is more stable? cylindrical or salient pole gen 26- when exciting of syn gen is off, it acts as? Ind gen*, ind motor, syn gen, syn motor 27- insulation resistance of cables relation with length? (inversly prop) 28- test used to find fault in under ground cables? (murrey loop*, etc) 29- when X/R=1, zero voltage regulation occur at p.f? (unity, leading 0.707*, lagging 0.707, zero) 30- real power transfer depends upon? (V diff,Angle diff*, Vs, Vr, delta s, delta r) 31- reactive power transfer depends upon? (V diff*, angle diff, Vs, Vr, etc) 32- power transfer angle practical value? (20, 30*, 45, 90) 33- Which type is common for overhead lines? All Al, all Cu, ACSR*, etc 34- communicaton system questions —about 8-10
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KRL TEST Ques
Q1- energy stored in an inductor? (1/2 LI 2) 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, 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 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 75%, 100%, 50%, 25%
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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 Q30-if 220 V dc series motor is given 220 V ac, then what will happen?
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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)
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