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WorksheetsTCEE_TKT
Total questions: 80
Worksheet time: 1hrs 20mins
Name
Class
Date
1.
The secondary winding of which of the following transformers is always kept closed?
a)
Current transformer
b)
Voltage transformer
c)
Power transformer
d)
Step down transformer
2.
If supply frequency of a transformer increases, the secondary output voltage of the transformer
a)
Increase
b)
Decrease
c)
Remain the same
d)
Any of the above
3.
Power transformers are designed to have maximum efficiency at
a)
Full load
b)
50% load
c)
80% load
d)
no load
4.
The open circuit test in a transformer is used to measure
a)
Copper loss
b)
Winding loss
c)
total loss
d)
core loss
5.
The essential condition for parallel operation of two single-phase transformer is that they should have the same
a)
KVA Rating
b)
Turn Ratio
c)
Polarity
d)
Both 2 & 3
6.
During open circuit test (OC) of a transformer _____________
a)
primary is supplied rated kVA
b)
primary is supplied full-load current
c)
primary is supplied current at reduced voltage
d)
primary is supplied rated voltage
7.
Why OC test is performed on LV side?
a)
Simple construction
b)
Less voltage is required and parameters can be transformed to HV side
c)
It’ll not give losses ig conducted on HV side
d)
HV side does not have connections for voltages
8.
In OC test all the power supplied is utilised for ______
a)
Core losses
b)
Iron losses
c)
Windage losses
d)
Cannot be determined above
9.
The total core loss can be termed as ____________
a)
Eddy current loss
b)
Hysteresis loss
c)
Copper loss
d)
Magnetic loss
10.
While conducting short-circuit test on a transformer which side is short circuited?
a)
High voltage side
b)
Low voltage side
c)
Primary side
d)
Secondary side
11.
During short circuit test why iron losses are negligible?
a)
The current on secondary side is negligible
b)
The voltage on secondary side does not vary
c)
The voltage applied on primary side is low
d)
Full-load current is not supplied to the transformer
12.
Short circuit test on transformers is conducted to determine ______
a)
Core losses
b)
Copper losses
c)
Hysteresis losses
d)
Eddy current losses
13.
Why SC test is not conducted on LV side?
a)
Difficult to arrange low voltage supply
b)
Difficult to arrange high current supply
c)
Difficult to arrange low voltage and high current supply to the LV
d)
SC test on LV does not give correct results
14.
Sumpner’s test is conducted on transformers to study effect of ____________
a)
Temperature
b)
Stray losses
c)
All-day efficiency
d)
Cannot be determined
15.
Which of the following tests are enough to find all the parameters related to a transformer?
a)
OC test
b)
OC, SC test
c)
OC, SC, Sumpner’s test
d)
Sumpner’s test
16.
Sumpner’s test is performed on _________
a)
Single transformer at a time
b)
Only two transformers at a time
c)
Minimum 2 transformers at a time
d)
Many transformers at a time
17.
When grounding transformer is employed?
a)
When neutral is available
b)
When neutral is not available
c)
When transformer of type Y/D is used
d)
Always
18.
What is the low voltage range according to the earthing procedures?
a)
5 V – 100 V
b)
10 V – 100 V
c)
50 V – 1000 V
d)
100 V – 1000 V
19.
Earthed neutral allows rapid operation of protection to ___________
a)
Line to line faults
b)
Earthed faults
c)
Other faults
d)
For all faults
20.
Which method will reduce the cost of insulation between earth and cables?
a)
Neutral solidly earthed
b)
Neutral earthed via an impedance
c)
Neutral isolated
d)
none of the above
21.
Earth contact material resistance should be ____________
a)
Less than 2 ohms
b)
More than 2 ohms
c)
Depends on the circuit or system
d)
Very high
22.
If parallel arrangement is done the minimum distance between two earthing conductors should be _______
a)
10 meters
b)
5 meters
c)
More than or equal to 10 meters
d)
2 meters
23.
Ingress of air into the oil tank can be avoided by using ___________
a)
relays
b)
plastic coatings
c)
metal coatings
d)
fuses
24.
When tripping of the transformer from the main circuit is required?
a)
Local overheating
b)
Short-circuited core laminations
c)
Core-bolt insulation failure
d)
Puncture of bushings
25.
Which of the following is the reason relating to the maintenance while operation?
a)
To obtain the maximum practicable operating efficiency
b)
To obtain optimum life
c)
To minimise the risk of premature and unexpected failure
d)
Maximum efficiency, life, minimum temperature
26.
Stored oil should be checked continuously for _________________
a)
impurities in the oil
b)
oil levels
c)
oil moisture content
d)
oil reactions
27.
For high reliability of transformer action, how many fundamental checks should be done?
a)
2
b)
3
c)
4
d)
cannot tell
28.
Dissolved gas contents are need to be observed because _____________________
a)
dissolved oxygen
b)
dissolved gases from outside air
c)
dissolved gases from arcs occurring in the transformer
d)
all dissolved gases
29.
What is the advantage of gas-monitor?
a)
Time delay
b)
Alarms at presence of a particular gas
c)
Less efficiency
d)
Requires low power
30.
Earthing is necessary to give protection against
a)
Danger of electric shock
b)
Voltage fluctuation
c)
Overloading
d)
High temperature of the conductors
31.
Solid grounding is addopted for voltages below
a)
100 V
b)
200 V
c)
400 V
d)
660 V
32.
In a star connected system without neutral grounding, zero sequence currents are
a)
Zero
b)
Phaser sum of phase currents
c)
Same as r.m.s. value of phase currents
d)
Same as peak value of phase currents
33.
The advantage of neutral earthing is
a)
Freedom from persistent arcing grounds
b)
Over voltages due to lightning can be discharged to earth
c)
Simplified design earth fault protection
d)
All of the above
34.
Which of the following single phase motors is relatively free from mechanical and magnetic vibration?
a)
Reluctance motor
b)
Hysteresis motor
c)
Universal motor
d)
Shaded pole motor
35.
If a single phase motor fails to start, the probable cause may be
a)
Open circuit in auxiliary winding
b)
Open circuit in many winding
c)
Blown fuses
d)
Any of the above
36.
The synchronous speed of a linear induction motor does NOT depend on
a)
Width of pole pitch
b)
Number of poles
c)
Supply frequency
d)
Any of the above
37.
Mark the possible causes of overheating of commutator in a DC machine.
a)
Overload
b)
Restricted ventilation
c)
Shorted winding
d)
Any of the mentioned
38.
Hopkinson’s test is also called regenerative test due to
a)
energy of one machine is used to drive other
b)
feedback
c)
losses are least
d)
extra motor is used
39.
In dc machine iron losses cause
a)
heating in core
b)
loss in efficiency
c)
all of the mentioned
40.
For squirrel cage and slip ring induction motor, cooling methods is efficient in
a)
squirrel cage induction motor
b)
slip ring induction motor
c)
both of the motors
d)
none of the mentioned
41.
The hydroelectric plants in the industry are best suited with
a)
closed circuit air cooling
b)
hydrogen gas
c)
direct water
d)
any of the mentioned
42.
If one of the phases of the supply breaks down, then the connected three phase induction motor
a)
continues to run as a single phase induction motor, provided load does does not increase beyond 57.7%
b)
stops operating after few seconds
c)
continues to run as single phase induction motor
d)
continues to run as two phase induction motor
43.
Which type of enclosure is provided for DC motors used in coal handling plants?
a)
Screen protected
b)
Open type
c)
Totally enclosed fan cooled
d)
Drip proof
44.
What parameter(s) is / are checked using the commissioning tests?
a)
Turbine speed
b)
Condenser vacuum
c)
Turbine governor valve opening
d)
All of these
45.
Which among these tests are included in high voltage tests?
a)
Power wet test
b)
Impulse voltage withstand tests
c)
Power frequency withstand test 1 minute dry
d)
All of these
46.
What type of insulated cable is preferred for distribution lines?
a)
PVC and XLPE
b)
PVC only
c)
XLPE only
d)
EPR and XLPE
47.
Which test is conducted to confirm the withstanding capabilities of insulation?
a)
One minute power frequency withstand test
b)
Lightning impulse withstand test
c)
Switching impulse withstand test
d)
All of these
48.
What data is provided from the no load test on induction motors?
a)
Core loss only
b)
Magnetising current
c)
No load power factor
d)
All of these
49.
What is the cause for mechanical overloads in the induction motors?
a)
Stalling
b)
Blowing of fuse
c)
Under voltage
d)
Open circuit
50.
Which sequence is followed first while closing a circuit breaker?
a)
Close the isolator
b)
Open earthing switch
c)
Close circuit breaker
d)
Any of these
51.
Which equipment is used for EHV lines to improve power transferability?
a)
Shunt capacitor
b)
Shunt reactor
c)
Series capacitor
d)
All of these
52.
What is the application of hollow porcelain insulator?
a)
Transformer bushing
b)
Wall bushing
c)
SF6 GIS bushing
d)
Only b and c
53.
Which type of structure is preferred in modern stations?
a)
Aluminium alloy structure
b)
Galvanised steel structure
c)
Fabricated structure
d)
All of these
54.
Which among these HVDC projects are commissioned in India?
a)
Rihand – Delhi HVDC
b)
Vindhyachal Back to Back only
c)
Chandrapur only
d)
All of these
55.
At what location are the shunt capacitors installed for voltages above 33 kV and above?
a)
Are located near the motors
b)
Are installed in distribution substations
c)
Both (A) and (B)
d)
Both (A) and (B)
56.
What is meant by Creepage Distance?
a)
Shortest distance between two conducting parts along a stretched string.
b)
Shortest distance between two conducting parts along the surface of the insulating material.
c)
Distance between ground and the highest earthed point on the equipment.
d)
All of these
57.
Which among these is a type of surge arrestor?
a)
Conventional gapped arrestors
b)
Metal oxide arrestors
c)
Horn gap arrestors
d)
none of these
58.
Which material is used for indoor bus bar?
a)
Copper
b)
Aluminium
c)
Silver
d)
Both (A) and (B)
59.
Which type of foundation is preferred for lattice towers?
a)
Rock foundation
b)
Pole foundation
c)
Anchor foundation
d)
All of these
60.
Corona rings are fixed on which among these?
a)
At cross arm end of the string assembly
b)
At corners of bus bar joints
c)
Only at contacts of isolators
d)
all of these
61.
At what level is the load shedding carried out?
a)
Distribution level
b)
Transmission level
c)
Both (A) and (B)
d)
Depending upon the load
62.
Which place is the ‘Regional load dispatch centre’ for the western region in the national grid?
a)
Mumbai
b)
Bhopal
c)
Nagpur
d)
banglore
63.
What type of insulation is preferred for DC smoothing Reactors?
a)
Air
b)
Oil
c)
Paper
d)
Varnish
64.
Lightening arrester should be located
a)
near CB
b)
away from the CB
c)
near transformer
d)
away from the transformer
65.
In power system lightning arresters are used to protect the electrical equipment against
a)
power frequency of over voltage
b)
Direct stroke of lightning
c)
over current due to lightening stroke
d)
over voltage due to indirect lighting stroke
66.
in an extra high voltage overhead transmission line earth wire is provided to protect the line against
a)
switching surges
b)
lghtening surges
c)
corona effect
d)
ensure fault voltages
67.
What test is performed to verify that the equipment is ready for energising fault in a power system severe over voltages are produced with neutral
a)
Maintenance test
b)
Commissioning test
c)
Type test
d)
Reliability test
68.
Which material has a lower dielectric strength at 50 Hz?
a)
Bakelite
b)
Glass
c)
Air
d)
Dielectric oil
69.
Above what ratings is it necessary to fix separate heat exchangers on the machines?
a)
Above 500 kW
b)
Above 300 kW
c)
Above 100 kW
d)
Above 1000 kW
70.
What is the application of synchronous motor of speed less than 750 rpm?
a)
Fans
b)
Pumps
c)
Ball mills
d)
Compressors
71.
Which factor is controlled by turbine and governor?
a)
Voltage
b)
Frequency
c)
Power factor
d)
All of these
72.
Which gel ensures the dryness of the incoming air in the breather?
a)
Potassium gel
b)
Silica gel
c)
Carbon gel
d)
All of these
73.
Which cooling system is employed for large transformers?
a)
Oil natural oil forced
b)
Oil natural air forced
c)
Oil forced air forced
d)
Both (b) and (c)
74.
Which among the following safety devices are provided on the power transformers?
a)
Marshalling kiosk
b)
Vacuum gauge
c)
Pressure relief gauge
d)
All of these
75.
Which among these gases is not used as a coolant?
a)
Hydrogen
b)
Nitrogen
c)
Carbon dioxide
d)
Helium
76.
On what factors does the size of the induction motor depend?
a)
Power output
b)
Frequency
c)
Speed of rotation
d)
Both (A) and (C)
77.
Hollow conductors are used in transmission lines to
a)
Reduce weight of copper
b)
improve stabilty
c)
reduce corona
d)
increase power transmission capacity
78.
What is the temperature limit for the storage of machines at site before installation?
a)
Temperature above + 25 °C
b)
Temperature above + 5 °C
c)
Temperature less than 10 °C
d)
Temperature above 15 °C
79.
What is the main cause of harmful vibrations in the machine?
a)
Mechanically unbalanced rotor
b)
Bent or cracked shaft
c)
An excessively pulsating load
d)
All of these
80.
Which type of rotor is used by Hydro Generators?
a)
Salient pole
b)
Cylindrical rotor
c)
Both (A) and (B)
d)
None of these
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