EEE - · PDF fileMCQ (i) A-t/m is the unit of – (a) ... jnrengineer.co.za/doc/electricity%20basics.pdf . ... 10 Write down the conditions of parallel operation of two alternators

EEE
Rony Parvejs
Lecture 5 & 6: MIST Special Update: 30 April, 2015
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Rony Parvejs EEE Question Bank Lecture-5 & 6: mist special
M.Sc. in EECE Admission Test Question of Military Institute of Science and Technology (MIST) Compiled by: Rony Parvej (IUT, EEE07)
Time: 90 minutes Full Marks: 100
Exam Date: 03.04.2015 Venue: MIST
1. MCQ
(i) A-t/m is the unit of (a) Flux density (b) Magnetic field intensity (c) Permeability (d) Flux
(ii) What is the unit of permeability? (a) A-t (b) A-t/m (c) H/m (d) Wb-t
(iii) In series RLC circuit when the frequency of the circuit is less than resonance frequency?
(a) XL>XC (b) XL< XC (c) XL=XC (d) None
(iv) What happens when power factor is increased?
(a) Reactive power is increased (b) Active power is increased
(c) Apparent power is increased (d) None
(v) What are linear circuit elements?
(a) the circuit elements whose parameters are not changed with change of voltage & current.
(b) (c) (d)
(vi) Voltage Regulation depends on
(a) Load current (b) Power pactor (c) both (d) none.
(vii) - (x). 2. Elaborate following words: PSM, IGCTs, DCPSK, CSDN, GTO, DGPS, CDMA, IDMT, SCADA
3. What is ideal transformer?
4. Write down the characteristics of an ideal Op-Amp.
5. What are the losses in an compound dc generator?
6. What are linear circuit element & bilateral linear circuit element?
7. What do you mean by coupling co-efficient between two coils is 0.6?
8. A series RLC circuit has R=1000 , L=100mH & C=10 F. Find:
(a) Resonance frequency
(b) Q-factor
(c) 3dB point
9. A 3-phase delta connected load has Z=2060 and line voltage is 400 V. Find:
(a) Total power
(b) Power consumed in each phase.
10. Write down the conditions of parallel operation of two alternators.
11. Write down four main differences between CT and PT.
12. Find the output of a full wave rectifier if the input is
13. Draw the following signals:
(b) x(t) = 2 u(t) + (t-1)

14. Find Vo
15. Find IE, IB and IC . ( was not given )
16. Find I1, I2 and V2 .
17. A power station has following loading:
Lighting load: 150 Kw for 7.00pm to 10.00pm
Residential load: 50KW for 7.00pm to 12.00pm
Pumping Load: 75KW for 3.00pm to 7.00pm
Find diversity factor.
18. Take 150 MVA, 15KV as base and draw the reactance diagram:

1.
(i)
A-t/m is the unit of
(a) Flux density (b) Magnetic field intensity (c) Permeability (d) Flux
(ii) What is the unit of permeability?
(a) A-t (b) A-t/m (c) H/m (d) Wb-t
Reference: Course material of University of Minnesota

(iii)
In series RLC circuit when the frequency of the circuit is less than resonance frequency?
(a) XL>XC (b) XL< XC (c) XL=XC (d) None
Before resonance frequency, fr capacitive reactance dominates and after resonance, inductive
reactance dominates and at resonance the circuit acts purely as resistive circuit causing a large amount
of current to circulate through the circuit. Reference: http://electrical4u.com/resonance-in-series-rlc-circuit/ & http://www.electronics-tutorials.ws/accircuits/series-resonance.html
So, series resonant circuit is inductive if it operates at a frequency higher than resonant frequency.
iv
What happens when power factor is increased?
(a) Reactive power is increased (b) Active power is increased
(c) Apparent power is increased (d) None
Ans: Active power is increased
v
What are linear circuit elements?
(a) the circuit elements whose parameters are not changed with change of voltage & current.
(b) (c) (d)
Ans: the circuit elements whose parameters are not changed with change of voltage & current
vi Voltage Regulation depends on
Load current (b) Power pactor (c) both (d) none.
voltage regulation depends not only on load current, but also on its power factor. Reference: jnrengineer.co.za/doc/electricity%20basics.pdf

2 Elaborate following words:
PSM, IGCTs, DCPSK, CSDN, GTO, DGPS, CDMA, IDMT, SCADA
PSM : Phase Shift Modulation
IGCTs : Integrated Gate-Commutated Thyristors
DCPSK: Differentially Coherent Phase Shift Keying
CSDN : Circuit Switched Data Network
GTO : Gate Turn Off (thyristor)
DGPS : Differential Global Positioning System
CDMA : Code Division Multiple Access
IDMT : Inverse Definite Minimum Time
SCADA: Supervisory Control and Data Acquisition
2. What is ideal transformer?
An ideal transformer is an imaginary transformer which does not have any loss in it, means no core
losses, copper losses and any other losses in transformer. Efficiency of this transformer is considered as
100%.
Write down the characteristics of an ideal Op-Amp.
1. Infinite Open-Loop Gain
2. Infinite Input Impedance
3. Infinite Bandwidth
4. Zero Output Impedance
5. Zero Noise Contribution
6. Zero output Offset
7. Differential Inputs Stick Together
Explanation:

What are the losses in an compound dc generator?
1. Copper losses
Armature Cu loss
Shunt Cu loss
Series Cu loss
2. Iron losses
Hysteresis loss
Eddy current loss
3. Mechanical losses
Friction loss
Windage lo

What are linear circuit element & bilateral linear circuit element?
Linear bilateral circuit element:
A linear circuit element is an electrical element with a linear relationship between current and voltage.
Resistors are the most common example of a linear element; other examples include capacitors, inductors,
and transformers.
Linear bilateral circuit element:
It is a circuit element that behaves the same way if it is connected in the opposite direction. For example,
a resistor behaves the same way no matter if it's connected left-to-right or right-to-left. In contrast, a diode
is not a bilateral component, because it conducts current in one direction, and does not conduct in the
other.
What do you mean by coupling coefficient between two coils is 0.6?
Coupling coefficient is a measure of the strength of interaction between two coils. coupling coefficient
between two coils is 0.6 means 60% of the flux set-up in one coil links the other coil. (Reference: Dictionary + Objective Electrical Technology By Mehta)
A series RLC circuit has R=1000 , L=100mH & C=10 F. Find:
(a) Resonance frequency
(b) Q-factor
(c) 3dB point
Bandwidth,
The upper and lower -3dB frequency points, H and L
Ans.

Similar:
Bandwidth of a Series Resonance Circuit
Series Resonance Example No1
A series resonance network consisting of a resistor of 30, a capacitor of 2uF and an inductor of
20mH is connected across a sinusoidal supply voltage which has a constant output of 9 volts at
all frequencies. Calculate, the resonant frequency, the current at resonance, the voltage across the
inductor and capacitor at resonance, the quality factor and the bandwidth of the circuit. Also
sketch the corresponding current waveform for all frequencies.
Resonant Frequency, r
Circuit Current at Resonance, Im

Inductive Reactance at Resonance, XL
Voltages across the inductor and the capacitor, VL, VC
( Note: the supply voltage is only 9 volts, but at resonance the reactive voltages are 30 volts peak! )
Quality factor, Q
Bandwidth, BW
The upper and lower -3dB frequency points, H and L
Current Waveform

Series Resonance Example No2
A series circuit consists of a resistance of 4, an inductance of 500mH and a variable
capacitance connected across a 100V, 50Hz supply. Calculate the capacitance require to give
series resonance and the voltages generated across both the inductor and the capacitor.
Resonant Frequency, r
Voltages across the inductor and the capacitor, VL, VC
Reference: http://www.electronics-tutorials.ws/accircuits/series-resonance.html
9
A 3-phase delta connected load has Z=2060 and line voltage is 400 V. Find:
(a

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EEE - · PDF fileMCQ (i) A-t/m is the unit of – (a) ... jnrengineer.co.za/doc/electricity%20basics.pdf . ... 10 Write down the conditions of parallel operation of two alternators