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Old 22nd August 2014, 09:01 AM
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Join Date: Apr 2013
Default Re: DMRC Exam Question paper for Junior Engineer (Electrical)

The Delhi Metro Rail Corporation Ltd. (DMRC) is a state owned company that operates the Delhi Metro in the National Capital Region of India.

Delhi Metro Rail Corporation Limited questions for the post of Junior Electrical Engineer are given below:
1. Mho relay is usually employed for the protection of
a) Short lines only
b) Medium lines only
c) Long lines only
d) Any line

Ans: Long lines only

2. A modern power semiconductor device IGBT is combines the characteristics of
a) BJT and MOSFET
b) FCT and GTO
c) SCR and MOSFET
d) SCR and BJT

Ans: BJT and MOSFET

3. For a single-phase a.c. to d.c. controlled rectifier to operate in regenerative mode, which of the following conditions should be satisfied?
a) Half –controlled bridge, α 90°, source of e.m.f. in load
c) Full-controlled bridge, α > 90°, source of e.m.f. in load
d) Full-controlled bridge, α 90°, source of e.m.f. in load

4. Which is the most suitable power device for high frequency ( more 100 kHz) switching application?
a) Power MOSFET
b) BJT
c) SCR
d) UJT

Ans: Power MOSFET

5. In a thyristor Latching current is ________ than Holding current
a) Equal
b) Less
c) Greater
d) None

Ans: Greater

6. The transfer function of a system is 10/(1+s) when operating as a unity feedback system, the steady state error to a step input will be
a) 0
b) 1/11
c) 10
d) Infinity

Ans: 1/11

7. Which one of the following statements for a dc machine which is provided with inter pole winding (IW) as well as compensating winding (CW) is correct
a) Both IW and CW are connected in series with Armature winding
b) Both IW and CW are connected in parallel with Armature winding
c) IW connected in series but CW is connected in parallel with Armature winding
d) CW connected in series but IW is connected in parallel with Armature winding

Ans: Both IW and CW are connected in series with Armature winding

8. A 0-10 mA PMMC ammeter reads 5mA in a circuit; its bottom control spring snaps out suddenly the meter will now read.
a) 5mA
b) 10mA
c) 2.5mA
d) 0

Ans: 0

9. A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will
a) Both increases
b) Both decreases
c) Increases and decreases
d) Decreases and increases

Ans: Both increases

10. Moving coil in dynamometer wattmeter connected
a) In series with fixed coil
b) Across supply
c) In series with load
d) Across load

Ans: Across supply

11. In an induction machine, if the air gap increased
a) Speed will be reduced
b) Efficiency will be improved
c) Power factor will be lowered
d) Breakdown torque will be reduced

Ans: Power factor will be lowered

12. A CRO screen has ten divisions on the horizontal scale. If a voltage signal 5 sin 314t+45 deg)is examined with a line base settings of 5 msec/div, the number of cycles of signal displayed on the screen will be
a) 0.5 cycles
b) 2.5 cycles
c) 5 cycles
d) 10 cycles

Ans: 2.5 cycles

13. A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are
a) 0.02, 600 W
b) 0.04, 580 W
c) 0.04, 1160 W
d) 0.04, 1200 W

Ans: 0.04, 1160 W

14. Thermocouple is used to measure
a) AC
b) DC
c) Both
d) None

Ans: Both

15. The two watt meters measurement the ratio of two meter readings is –(1-sqrt3) 1+sqrt3) then the power factor is

a) 1
b) 0.866
c) 0.707
d) 0

Ans: 0.707

16. Hays bridge is used to measure___________ and Schering bridge is used to measure____________

a) Inductance, Inductance
b) Inductance, Capacitance
c) Capacitance, Inductance
d) Resistance, Capacitance

Ans: Inductance, Capacitance

17. When sine wave is given as input to Schmitt trigger then its generates

a) Sine wave
b) Saw tooth wave
c) Triangle wave
d) Square wave

Ans: Square wave

18. In Gauss Seidel method the following factors are influenced for operation

a) Acceleration factor
b) Selection of slack buss
c) Both
d) None

Ans: Selection of slack buss*

19.
i. (X’+Y’) A. Low-pass filter function
ii. (X’Y’) B. Sum
iii. (XY) C. NAND
D. Carry
E.NOR

a) i-C, ii-E, iii-D
b) i-C, ii-E, iii-B
c) i-C, ii-B, iii-D
d) i-C, ii-E, iii-A

Ans: i-C, ii-E, iii-D

20. The phase lead compensation is used to
a) Increase rise time and decrease overshoot
b) Decrease both rise time and overshoot
c) Increase both rise time and overshoot
d) Decrease rise time and increase overshoot

Ans: Decrease rise time and increase overshoot

21. Voltage feed back amplifier is a

a) Shunt-Shunt
b) Shunt-Series
c) Series-Shunt
d) Series- Series

Ans: Shunt-Shunt

22. In microprocessor the next instruction to be executed is stored in

a) Program Counter
b) Stack Pointer
c) Memory Pointer
d) Accumulator

Ans: Program Counter

23. The following element retains it energy after source is disconnected

a) Resister
b) Inductor
c) Capacitor
d) Thermistor

Ans:

24. In series RLC circuit at resonant

a) Voltage is in phase with current
b) Current is maximum
c) Inductive reactance = Capacitive reactance
d) All of the above

Ans: All of the above

25.For RC low pass filter R=100 K ohms, C= 5 micro farads then lower cutt of frequency is

a) 1 K HZ
b) 0 HZ
c) 381.3 HZ
d) Infinity

Ans:

26. V=100Sin (1000t+46 deg), I=2Sin (1000t+80 deg) what are the elements in the circuit

a) R=30 ohm, L=30 mH
b) R=30 ohm, C=33.3 micro farads
c) R=40 ohm, L=30 mH
d) R=40 ohm, L=33.3 micro farads

Ans: R=40 ohm, L=33.3 micro farads
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