Month: February 2022

power system mcq

Power System MCQ

Power System / By
1.The charging current in a transmission line
  1. Lags the voltage by 900
  2. Leads the voltage by 450
  3. Leads the voltage by 900
  4. Leads the voltage by 1800

Answer: 3

2. As the transmission voltage increases, the percentage resistance drop
  1. Increase
  2. Decrease
  3. Remain same
  4. None

Answer: 2

3. The coefficient of reflection for current for current for an open ended line is
  1. 1
  2. 0.5
  3. -1
  4. 0

Answer: 3

4. Ferranti effect on long overhead line is experienced when it is
  1. Lightly loaded
  2. On full load at upf
  3. On full load at 0.8pf
  4. On full load at zfp

Answer: 1

5. For an overhead line, the surge impedance in taken as
  1. 40 ohm
  2. 80 ohm
  3. 100 ohm
  4. 400 ohm

Answer: 4

Also Read

Transformer MCQ

Series & parallel connections of Resistance

6. For a good voltage profile under no load conditions a long line needs,
  1. Shunt capacitors at receiving end
  2. Shunt reactors at receiving end
  3. Shunt resistance at receiving end
  4. Shunt capacitor at sending end

Answer: 2

7. Corona loss is on hilly areas than as plains areas
  1. less
  2. Same
  3. more
  4. None

Answer: 3

8. In any transmission line, AD-BC=
  1. 1
  2. 0
  3. -1
  4. 2

Answer: 1

9. If the p.f of load decrease, the line losses,
  1. Increase
  2. Decrease
  3. Remain same
  4. None

Answer: 1

10. The nature of line constants in the rigorous solution of transmission line is
  1. Distributed parameter
  2. Lumped parameter
  3. Both
  4. None

Answer: 1

My Youtube Channel

Electrical Stuff 4U

transformer mcq

Transformer MCQ

Electrical Machines / By
Previous
1. No –load test on a transformer is carried out to determine
  1. Copper loss
  2. Magnetizing current
  3. Magnetizing current and no-load loss
  4. Efficiency of the transformer

Answer: 3

2. The main purpose of performing open –circuit test on a transformer is to measure its
  1. Cu loss
  2. Core loss
  3. Total loss
  4. Insulation resistance

Answer: 2

3. During short –circuit test, the iron lose of a transformer is negligible becauseer is to measure its
  1. The entire input is just sufficient to meet Cu losses only
  2. Flux produced is a small fraction of the normal flux
  3. Iron core becomes fully saturated
  4. Supply frequency is held constanton resistance

Answer: 2

4. In operating a 400 Hz transformer at 50 Hz
  1. Only voltage is reduced in the same proportion as the frequency
  2. Only KVA rating is reduced in the same proportion as the frequency
  3. Both voltage and KVA rating are reduced in the same proportion as the frequency
  4. None of the above

Answer: 2

5.Transformer are rated in KVA instead of KW because
  1. Load power factor is often not known
  2. KVA is fixed whereas KW depends on load p.f.
  3. Total transformer loss depends on volt-ampere
  4. It has become customary

Answer: 3

Also Read:

Resistance in series and parallel connection

Power System MCQ

6. What is Transformer?
  1. Transformer is a device used to convert low alternating voltage to a high alternating voltage
  2. Transformer is a device used to convert alternating current to direct current
  3. Transformer is a device used to convert low alternating current to a high alternating current
  4. Transformers are used only for low alternating voltage

Answer: 1

7. Transformer ratings are given in _____________
  1. kVA
  2. HP
  3. kVAR
  4. kW

Answer: 1

8. What is the current transformer?
  1. transformer used with an A.C. voltmeter
  2. transformer used with an A.C. ammeter
  3. transformer used with an D.C. voltmeter
  4. transformer used with an D.C. ammeter

Answer: 2

9. Current transformers are _______________
  1. parallel connected type of instrument transformers
  2. series connected type of instrument transformers
  3. parallel connected normal transformers
  4. series-parallel connected type of instrument transformers

Answer: 2

10. Which of the following is not a part of transformer installation?
  1. Breather
  2. Conservator
  3. Exciter
  4. Buchholz relay

Answer: 3

My Youtube Channel

Electrical Stuff 4U

transformer mcq

Transformer MCQ

Electrical Machines / By
Previous
Next
1. A transformer having 1000 primary turns is connected to a 250-V A.C. supply. For a secondary voltage of 400 V, the number of secondary voltage of 400V, the number of secondary turns should be
  1. 1600
  2. 250
  3. 400
  4. 1250

Answer: 1

2. A step –up transformer increases
  1. Voltage
  2. Current
  3. Power
  4. frequency

Answer: 1

3. The primary and secondary windings of an ordinary2-winding transformer always have
  1. Different number of turns
  2. Same size of copper wire
  3. A common magnetic circuit
  4. Separate magnetic circuit

Answer: 3

4. In a transformer, the leakage flux of each winding is proportional to the current in that winding becauseer always have
  1. Ohm’s law applies to magnetic circuits
  2. Leakage paths do not saturate
  3. The two windings are electrically isolated
  4. Mutual flux is confined to the core

Answer: 2

5. In a two-winding transformer, e.m.f. per turn secondary winding is always the induced e.m.f. per turn in primary
  1. Equal to k times
  2. Equal to 1/k times
  3. Equal to
  4. Greater than

Answer: 3

Related Posts :-

Transformer MCQ

Why we need Transformer

6. In relation to a transformer, the ratio 20:1 indicates that
  1. There are 20 turns on primary one turn on secondary
  2. Secondary voltage is 1/20thof primary voltage
  3. Primary current is 20 times greater than the secondary current
  4. For every 20 turns on primary, there is one turn on secondary

Answer: 4

7. In performing the short circuit test of a transformer
  1. High voltage side is usually short circuited
  2. Low voltage side is usually short circuited
  3. Any side is short circuited with preference
  4. None of the above

Answer: 2

8. The equivalent resistance of the primary of a transformer having k=5 and R1=0.1 ohm when referred to secondary becomes __ohm.
  1. 0.5
  2. 0.02
  3. 0.004
  4. 2.5

Answer: 4

9. A transformer has negative voltage regulation when its load power factor is
  1. Zero
  2. Unity
  3. Leading
  4. Lagging

Answer: 3

10. The primary reason why open circuit test is performed on the low-voltage winding of the transformer is that it.
  1. Draw sufficiently large no-load current for convenient
  2. Requires least voltage to perform the test
  3. Needs minimum power input
  4. Involves less core less

Answer: 1

My Youtube Channel

Electricalstuff4u

power system mcq

Power System MCQ

Power System / By
Previous
1. ACSR conductor have
  1. all conductors made of aluminium
  2. outer conductors made of aluminium
  3. inner conductor made of aluminium
  4. core made of aluminium

Answer: 2

2. If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency, will
  1. increase
  2. decrease
  3. remain unchanged
  4. may increase or decrease

Answer: 3

3. If the length of a transmission line is increased its capacitance will
  1. increase
  2. decrease
  3. remain same
  4. increase or decrease

Answer: 1

4. The line parameters are (a) Shunt reactance (b) Series reactance (c) Conductance (d) Resistance
  1. a and b
  2. a and c
  3. b,c and d
  4. a,b,c and d

Answer: 4

5. The skin effect does not depends on,
  1. nature of material
  2. size of wire
  3. supply frequency
  4. temperature

Answer: 4

Also Read

MCQ on Electrical Machines

MCQ on Transformer

6. For OH transmission line, the self GMD method is used to find
  1. Capacitance
  2. Inductance
  3. Both
  4. None

Answer: 4

7. ACSR conductor have the central core made of
  1. Copper
  2. Steel
  3. Aluminium
  4. Cadmium

Answer: 2

8. Which of the following conductor spirality effect is ignored
  1. Magnetic
  2. Non-magnetic
  3. Both
  4. None

Answer: 2

9. Highest transmission voltage in India
  1. 400 KV
  2. 450 KV
  3. 500 KV
  4. 750 KV

Answer: 4

10. If the height of transmission tower is increased,
  1. line capacitance increases and line inductance decreases
  2. line capacitance decreases and line inductance increases
  3. line capacitance remain same and line inductance decreases
  4. line capacitance decreases and line inductance remain same

Answer: 4

My Youtube Channel

Electrical Stuff 4u

power system mcq

Power System MCQ

Power System / By
Next
1. If the conductor diameter decreases, inductance of the line,
  1. increases
  2. decreases
  3. remaining same
  4. cannot be determined

Answer: 1

2. A conductor carries more current on the surface as compared to core. This is called as
  1. Permeability
  2. Corona effect
  3. Skin effect
  4. Unsymmetrical fault

Answer: 3

3. The inductance of a line is minimum when,
  1. GMD is high
  2. GMR is high
  3. GMD and GMR are high
  4. GMD is low and GMR is high

Answer: 4

4. The economic size of a conductor is determined by,
  1. Kelvin’s law
  2. Kirchoff’s law
  3. Faraday’s law
  4. All of the above

Answer: 1

5. Skin effect depends upon,
  1. Supply frequency
  2. Size of conductor
  3. Nature of material
  4. All of the above

Answer: 4

Also Read

What is Electrical Resistance

Electrical Energy

6. The DC resistance of conductor is less than AC resistance due to,
  1. Skin effect
  2. Proximity effect
  3. Both
  4. None

Answer: 3

7. For increasing the capacity of a transmission line, to transmit power,which of the following must be decreased.
  1. Voltage
  2. Line inductance
  3. Capacitance
  4. All

Answer: 2

8. Use of bundled conductor increases,
  1. GMR
  2. GMD
  3. Potential gradient
  4. Radius of conductor

Answer: 1

9. Which of the following is not a standard transmission voltage.
  1. 400 KV
  2. 11 KV
  3. 190 KV
  4. 750 KV

Answer: 3

10. The overall diameter ‘D’of a standard conductor is given in terms of diameter of each strand ‘d’ and no. of layers ‘n’ as,
  1. D = 2(n-1)d
  2. D = 2n-1/d
  3. D = 2(2n-1)d
  4. D = 2(n-D)d

Answer: 3

My Youtube Channel

Electrical Stuff 4U

electrical machines mcq

Electrical Machines MCQ

Electrical Machines / By
Previous
1. The normal value of the armature resistance of a D.C motor is
  1. 0.005
  2. 0.5
  3. 10
  4. 100

Answer: 2

2. The Eb/V Ratio of a D.C motor is an indication of its
  1. Efficiency
  2. Speed regulation
  3. Starting torque
  4. Running torque

Answer: 1

3. The mechanical power developed by the armature of a D.C. motor is equal to
  1. Armature current multiplied by back e.m.f.
  2. Power input minus losses
  3. Power output multiplied by efficiency
  4. Power output plus iron losses

Answer: 1

Transformer Installation

4. The induced e.m.f .in the armature conductors of a D.C. motor is
  1. Sinusoidal
  2. Trapezoidal
  3. Rectangular
  4. alternating

Answer: 1

5. D.C motor can be looked upon as D.C. generator with the power flow
  1. Reduced
  2. Reversed
  3. Increased  
  4. Modified

Answer: 2

Also Read

Basic Electrical MCQ

Why we need Transformer

6. In a D.C. motor, the mechanical output power actually comes from.
  1. Field system
  2. Air- gap flux
  3. Back e.m.f.
  4. Electrical input power

Answer: 4

7. The maximum torque of D.C. motor is limited by
  1. Commutation
  2. Heating
  3. Speed
  4. Armature current

Answer: 1

8. which of the following quantity maintains the same direction whether D.C. machine runs as a generator or as a motor?
  1. Induced e.m.f
  2. Armature current
  3. Field current         
  4. supply current

Answer: 1

9. Under constant load conditions, the speed of a D.C. motor is affected by
  1. Field flux               
  2. Armature current
  3. Back e.m.f.                     
  4. Both (b) and(c)

Answer: 1

10. It is possible to increases the field flux and, at the same time, increase the speed of a D.C. Motor provided its- is held constant
  1. Applied voltage
  2. Torque
  3. Armature circuit resistance                  
  4. Armature current

Answer: 4

11. The current drawn by a 120-v D.C Motor of armature resistance 0.5 ohm and back e.m.f 110 V is ________ amperer
  1. 20
  2. 240
  3. 220                  
  4. 5

Answer: 1

12. The shaft torque of D.C. motor is less than its armature torque because of _________________ losses
  1. Copper 
  2. Mechanical
  3. Iron                
  4. rotational

Answer: 4

My Youtube Channel

Electrical Stuff 4u