VIZAG MT EE FREE ONLINE TEST 1 ANSWERS KEY & EXPLANATION

1.Total
no of questions 20. 2.To marks 20 3.There is no negative marking. 4.Minimum
passing marks 30 percentage.
1.
If
the excitation is critical, the power factor of the alternator is
  1. none of the above
  2. leading power factor
  3. *unity power factor
  4. lagging power factor
the
generator neither supplies nor draws any reactive power and operates at unity
power factor.
 
2.
Lowest
critical frequency is due to pole and it may be present origin or nearer to
origin, then it is which type of network?
  1. Any of the above
  2. RL
  3. LC
  4. *RC
In
RC network lowest critical frequency is due to pole and it is at origin or
nearer to origin depending on the value of the capacitance value and transfer
function.
 
3.
Eddy
current loss will depends on
  1. *All of the above
  2. Flux density
  3. Frequency
  4. Thickness
eddy
current loss will depend upon frequency, flux density and the area of the
eddy current loop.
 
4.
In
an SR latch built from NOR gates, which condition is not allowed
  1. *S=1, R=1
  2. S=0, R=1
  3. S=0, R=0
  4. S=1, R=0
At
S=0, R=0, Output of the latch becomes Q=0, B_bar=0, which is an unwanted
state. also known as indeterminate state.
 
5.
In
a single phase induction motor, the starting torque developed is proportional
to
  1. 1/V
  2. *V²
  3. supply voltage V
  4. 1/V²
torque
developed is proportional to V².
 
6.
A
single phase full bridge inverter can operated in load commutation mode in
case load consist of
  1. RLC critically damped.
  2. *RLC underdamped.
  3. RL
  4. RLC overdamped
In
this case reading current will flow in circuit and it will became zero so
thyristor will be load commutated .
 
7.
Magnetic
flux has the unit of
  1. Tesla
  2. Ampere turn
  3. Newton
  4. *Weber
The
unit of magnetic flux is called Weber in honor of famous scientist Wilhelm
Eduard Weber (1804 – 1891). Magnetic flux has also another unit named
Maxwell. 1 Maxwell = 10-8 Weber.
 
8.
Ward-Leonard
control is basically a ___________ control method.
  1. Field diverter
    control.
  2. Armature resistance
    control.
  3. Field control.
  4. *Armature voltage
    control.
Ward-Leonard
speed control method consists a motor with a constant excitation and applying
a variable voltage to its armature to provide the required speed. Hence it is
armature voltage control method.
 
9.
The
value of diversity factor is
  1. *greater than 1
  2. 1
  3. 0
  4. less than 1
Diversity
factor is defined as the ratio of sum of individual maximum demand to the
station maximum demand. Maximum demand of each consumer does not occur at the
same time. They occur at different time of the day. So their sum is always
greater than the maximum demand a particular time. Therefore, diversity
factor value is more than 1.
 
10.
Which
of the following is the analogous quantity for mass element in force-voltage
analogy?
  1. all of the above
  2. *inductance
  3. resistance
  4. capacitance
The
electrical equivalents of the mechanical elements is known as analogous
system. Mechanical element ———– Electrical analogous element 1. Mass
element (M) ———- Inductance (L) 2. Spring element (K) ——— Inverse
capacitance (1/C) 3. Dash-pot (B) ————– Resistance (R) 4. Velocity
(v) —————– Current (i) 5. Displacement (x) ———– Charge (q)
6. Force (f) ——————— Voltage (V)
 
11.
Per
unit of any quantity is defined as
  1. base value of quantity
    /actual value of quantity in different units
  2. actual value of
    quantity /base value of quantity in different units
  3. *actual value of
    quantity /base value of quantity in same units
  4. base value of quantity
    /actual value of quantity in same units
Per
unit of any quantity is defined as the ration of actual value of quantity to
the base value of quantity in same units. Per unit of any quantity = Actual
value of quantity /Base value of quantity in same units
 
12.
How
many bits are required to store one BCD digit ?
  1. *4
  2. 2
  3. 1
  4. 3
BCD
(Binary coded Decimal) Number is from 0 to 9, which requires four bits to
store. As the maximum number of the system (15) can best represented by 4
bits. It is also called as 8421 code to represent maximum number 15.
 
13.
Which
statement is true for latching current ?
  1. none
  2. It is related to
    conduction process of device.
  3. It is related to turn
    off process of the device.
  4. *It is related to turn
    on process of the device.
Latching
current is the minimum required anode current to turn on SCR.
 
14.
What
is/are the necessary conditions for parallel operation of alternators?
  1. *Terminal voltage is
    same & Frequency should be same
  2. Frequency should be
    same
  3. Terminal voltage is
    same
  4. Speed of alternators
    should be same
Necessary
conditions for parallel operation of alternators are Terminal voltage is same
Frequency should be same Phase sequence should be same
 
15.
The
resistivity of the conductor depends on
  1. none of these.
  2. length of the
    conductor.
  3. area of the conductor.
  4. *type of material.
The
resistivity is a property of material, defined as the resistance between two
opposite faces of a cube of a material of unit volume. That is why
resistivity is only the unique property of material and it does not depend
upon the dimension of any piece of material.
 
16.
Which
of the following motor is suitable for frequent starting and stoppings?
  1. all of the above.
  2. capacitor start
    capacitor run motor
  3. *capacitor start motor
  4. resistance split phase
    motor
In
capacitor start motor, there is a capacitor in the starting winding through a
centrifugal switch. When the stator is supplied with 1-phase supply the
stator currents, main winding current Im and starting winding current Is has
a phase difference as near to 80° with the help of the capacitor and the
motor is nearly a perfect two phase motor. This produce a rotating magnetic
field and high starting torque with low starting current in the starting
winding. Therefore capacitor split phase motor is preferred for frequent
starting and stopping like refrigerators, grinders etc. The capacitor used
for frequent starting is dry type electrolytic capacitor.
 
17.
Which
of the following is/are base load plants?
  1. *all of the above
  2. hydro plants
  3. thermal plants
  4. nuclear plants
Base
load plants: A base load power plant is a power station that usually provides
a continuous supply of electricity throughout the year with some minimum
power generation requirement. Base load power plants will only be turned off
during periodic maintenance, upgrading, overhaul or service. Base load power
plant has the character of slow demand respond, a mechanism to match
generation with the load it supplies. Some examples of base load plants are
1. Thermal plants 2. Hydro plants 3. Nuclear plants 4. Tidal power
plants
 
18.
Breaking
current is a —————— value?
  1. any of the above
  2. average
  3. *RMS
  4. maximum
he
instantaneous maximum or peak value of the current flowing through the
circuit breaker at the instant of closing of circuit breaker is called making
current. Making current = 2.55 × Breaking current
 
19.
If
field current is decreased in shunt dc motor, the speed of the motor
  1. none of the above
  2. *increases.
  3. remains same
  4. decreases.
As
a shunt field current If decreases, φ also decreases and the speed rises as
speed is inversely proportional to flux.
 
20.
Which
of the following statements is/are correct?
  1. None of the above
  2. Transformer size get
    reduced at high frequency
  3. High frequency power
    supplies are light weight
  4. *Both 1 and 2
From
the induced emf equation of transformer E ∝ φf For same emf, φf = constant
φ1f1 = φ2f2 B1A1f1 = B2A2f2 For constant flux density B1 = B2 A1f1 = A2f2
For high frequency f2 > f1 A2 < A1 Therefore at high frequencies
transformer size get reduced and also light weight.
 
Power Systems (Generation) Expected MCQ PDF 2 For VIZAG MT Exam 2017
DMRC RECRUITMENT 2016 OFFICIAL TENTATIVE DATE OF RESULT DECLARATION

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