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### Transcript of entrance-exam.netentrance-exam.net/forum/attachments/general-discussion/... · Web viewD....

1)_____________ types of Induction Motor are widely used.

A. SlipringIM

B. Squirrel Cage IM

C. Single Phase IM

D. Three Phase IM

2) A 3, 12 pole, 600 V, 50 Hz star connected IM has rotor resistance and stand still resistance of 0.03&ohm; and 0.5 &ohm; respectively. The speed of maximum torque will be

A. 470 r.p.m

B. 450 r.p.m

C. 240 r.p.m

D. 540 r.p.m

3) Star-delta method of starting of motor is not possible in case of

A. High speed motor

B. Low horse power motor

C. Single phase Induction motor

D. High torque motor

4) In case of IM the torque is

A. inversely proportional to slip

B. directly proportional to slip

C. directly proportional to slip2

D. inversely proportional to slip

5) In case of 3-phase IM, plugging means

A. Pulling the motor directly on line without a rotor

B. Locking of rotor due to harmonics

C. Interchanging two supply phases for quick stopping

D. Starting the motor on load which is more than the rated load

6)In a star-delta starting of an IM.

A. reduced voltage is applied to the stator

B. applied voltage per stator phase is 57.7% of a line voltage

C. line voltage is 57.7% of stator voltage

D. resistance is inserted in the rotor

7) Which of the following is not determined by circle diagram

A. Power factor

B. frequency

C. Efficiency

D. Output

8) An IM rotor input is 4500 watts and rotor cu loss is 300 watts, find slip.

A. 6.67%

B. 15%

C. 7.77%

D. Cant be determined

9) For a 3 transmission line transmission efficiency of a line decreases with

B. Does not vary with power factor

10) Which combination is true for any transmission line

A. A = 52, B = 0.8, C = 25, D = 0.385

B. . A = 42, B = 2.1, C = 29, D = 0.5

C. A = 45, B = 3.2, C = 28, D = 0.83

D. A = 22.69, B = 0.7, C = 32, D = 0.68

11) If in a short transmission line, resistance and reactance are found to be equal and regulation appears to be zero, then the load will be

B. 0.707 lagging

C. have unity power factor

D. have zero power factor

12) When a neutral point of 3 system is directly connected to earth then it has what type of grounding

A. solid

B. resistance

C. reactance

D. Peterson coil

13) Percentage of carbon is highest in

A. anthracite coal

B. bituminous coal.

C. lignite .

D. coal gas.

14) The 1st nuclear plant in world was commissioned in

A. U.S.S.R

B. U.S.A

C. UAE

D. ENGLAND

15) The concept of an electrically short, medium and long line is primarily based on

A. nominal voltage of the line

B. physical length of the line

C wavelength of the line

D. power transmitted over the line

16) Keeping in view the cost and overall effectiveness, the following circuit breaker is suited for capacitor bank switching

A. vacuum

B. oil

C. air blast

D. SF6

17) In a biased differential relay the bias is defined as the ratio of

A. fault current and operating coil current

B. operating coil current and restraining coil current

C. number of turns of restraining and operating coil

D. fault current and restraining coil current

18) The bridge used to measure insulation of cable is-

A. Wien

B. Schering

C. Maxwell

D. Kelvin

19) In a synchronous motor ,the inverted curve represent the relation between-

A. Field current & Armature current

B. Armature curret & Power factor

C. Field current & Power factor

D. none of these

20) If the rotor power output of 3 phase induction motor is 12 Kw ,the rotor copper losses at slip of 5% will be-

A. 600 W

B. 625 W

C. 650 W

D. 700 W

21) What are the factors on which the hysteresis loss depend

A. frequency

B. frequency&fluxdensity

C. magnetic flux intensity

D. none of these

22) The MOSFET switch is onstate may be considered equivalent to-

A. capacitor

B. inductor

C. resistor

D. battery

23) Power is drawn from a source at p.f. 0.8,Pav=200 W,the reactive power is given by

A. 200 VAR

B. 150 VAR

C. 160 VAR

D. 120 VAR

24) VSWR can have value of between-

A. 0&1

B. 1&

C. 0&

D. -1&1

25) In single pulse modulation PWM inverters sixth harmonic can be eliminated if pulse width equal to-

A. 30 Degree

B. 60 Degree.

C. 36 Degree

D. 1080 Degree

26) Equal area criterion gives the information regarding-

A. Stability region

B. relative stability

C. absolute stability

D. swing curves

27) A megger is used for measurement of-

A. Low resistance

B. medium resistance

C. High valued resistance, particularly insulation resistance

D. all of these

28) The high torque by weight ratio in an analog indicating instrument indicates

A. High friction loss

B. Fast response.

C. Slow response.

D. None of above

29) In active filter which element is absent

A. inductor

B. capacitor

C. both

D. resistor

30) Peterson coil is used in

A. dc power transmission line

B. ac transmission line

C. dc motor

D. both a and b

31) How does the depth of laying affect the current carrying capacity of cables

A. decreases

B. increases

C. unchanged

D. doubles

32) The phase of lead compensator of the system G(s)= s+a/s+b is maximum at

A. ab

D. a/b

33) In a balanced wheatstone bridge if positions of detector and source are interchanged then bridge will still remain balanced . The inference can be drawn from

A. duality

B. reciprocity theorem

C. compensation theorem

D. both a and b

34) When compared a 1st order LPF a 2nd order LPF has

A. lower voltage gain

B. higher voltage gain

C. higher cut off frequency

D. faster drop in filter response

35) Load frequency control is achieved by properly matching the individual machine

A. turbine inputs

B. reactive powers

C. generated voltages.

D. generator ratings.

36) In O.C test which side is kept open

A. h.v side

B. l.v side

C. any one

D. both

37) ALL DAY ENERGY EFFICIENCY is related to which of the transformer

A. distribution transformer

B. C.T

C. P.T

D. power transformer

38) At slip s=1 torque developed in machine is

A. starting torque.

B. maximum torque

C. electromagnetic torque

D. none

39) Strain insulator is used for voltage level of

A. >33KV

B. 66KV

D. 132KV

1051) Effect of temperature on internal resistance of a battery

A. directly proportional

B. inversely proportional

C. no effect

D. none of these

40) What dielectric material are used in the capacitor used for pf correction

A. vacuum

B. oil impregnated paper

C. mica

D. glass

41) dummy strain gauges are used for

A. compensation of temperature changes

B. increase sensitivity of bridge

C. calibration purpose

D. all

42)LEAD NETWORK is used to improve

A. improve transient response

B. both a and c

C. increase bandwith

43) De Sauty bridge best suited for

A. capacitors with dielectric loss

B. lossless air capacitors

C. high Q

D. low Q

44) For a fixes value of complex power flow in a transmission line having a sending end voltage V, REAL POWER LOSS will be proportional to

A. V

B. 1/V 22

C. 1/V

D. V 22

45) Q meter works on principle of

A. mutual inductance

B. series resonance

C. self inductance

D. parallel resonance

46) The positive reactance equals to negative sequence reactance if equipment is

A. motor

B. transformer and transmission line

C. generator

D. all of these

47) A synchronous generator is feeding a zero power factor(lagging) load at rated current,the armature reaction is

A. magnetizing

B. cross -magnetizing

C. ineffective

D. demagnetizing.

48) A moving iron voltmeter is connected across thwe voltage source whose instantaneous value V(t)=5+10cos(314+30 degree).The reading of the meter is-

A. (75) V.

B. 15 V .

C. (125) V .

D. 5 V.

49) How many Flipflops are required to build a binary counter circuit to count from 0 to 1023.

A. 6

B. 24

C. 10

D. 12

50) If a shunt generator delives 100 A at 200V, and the resistances of the shunt field and armature are 100 ohms. And 0.01 ihms respectively, the generator e.m.f. will be

A. 212 V

B. 205 V

C. 210 V

D. 201.02 V

51) The bridge method commonly used for finding mutual inductance is

A. Scher