Last Answer : Satisfactory commutation of D.C. machines requires brushes should be of proper grade and size, brushes should smoothly run in the holders, smooth, concentric commutator properly undercut.
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108 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Brushes of D.C. machines are made of carbon.
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87 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Hopkinson's test on D.C. machines is conducted at full-load.
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99 views
1 answer
asked
Mar 20, 2018
by
anonymous

Draw the connection diagram of long shunt differential D.C. compound generator.
Last Answer : Ans:
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21 views
1 answer
asked
Jan 8, 2021
by
anonymous

DC shunt motor
Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
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140 views
2 answers
asked
Apr 23, 2020
by
anonymous

If field current is decreased in shunt dc motor, the speed of the motor (a) remains same. (b) increases. (c) decreases. (d) none of the above.
Last Answer : increases
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2.8k views
4 answers
asked
Aug 25, 2019
by
anonymous

State any four applications of DC shunt motor.
Last Answer : Applications of DC shunt motor: 1) Lathe machines 2) drilling machines 3) milling machines 4) Printing machinery 5) Paper industry 6) centrifugal and reciprocating pumps 7) blowers 8)fans
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115 views
2 answers
asked
Jul 27, 2019
by
anonymous

Why does the speed of a DC shunt motor decrease as the load increases?
Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.
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2.7k views
1 answer
asked
Jul 5, 2019
by
anonymous

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be
Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V
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483 views
1 answer
asked
May 8, 2018
by
anonymous

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is
Last Answer : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm
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332 views
1 answer
asked
May 3, 2018
by
anonymous

Last Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.
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158 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : D.C. shunt motors are used for driving machine tools.
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85 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.
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203 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.
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168 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.
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135 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The armature torque of the D.C. shunt motor is proportional to armature current.
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210 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.
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142 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.
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367 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
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250 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a D.C. shunt motor, speed is independent of armature current.
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87 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.
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148 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In D.C. shunt motors as load is reduced the speed will remain almost constant.
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145 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.
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135 views
1 answer
asked
Mar 20, 2018
by
anonymous

In dc machines, the armature windings are placed on the rotor because of the necessity for (1) electromechanical energy conversion (2) generation of voltage (3) commutation (4) development of torque
Last Answer : 3 Commutation
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292 views
2 answers
asked
May 1, 2018
by
anonymous

Last Answer : In D.C. machines the residual magnetism is of the order of 2 to 3 percent.
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502 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In D.C. machines fractional pitch winding is used to reduce the sparking.
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355 views
1 answer
asked
Mar 20, 2018
by
anonymous

A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave?
Last Answer : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.
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178 views
1 answer
asked
Mar 21, 2018
by
anonymous
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Last Answer : A cumulatively compounded long shunt generator when operating as a motor would be differentially compounded long shunt.
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111 views
1 answer
asked
Mar 21, 2018
by
anonymous

The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be?
Last Answer : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be 580 V.
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669 views
1 answer
asked
Mar 21, 2018
by
anonymous

In a shunt generator the voltage build up is generally restricted by?
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145 views
0 answers
asked
Mar 21, 2018
by
anonymous

A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly?
Last Answer : 200V/E2 = 1000/1200 E2= 240 V
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1.8k views
2 answers
asked
Mar 21, 2018
by
anonymous

Last Answer : For a D.C. machines laboratory following type of D.C. supply will be suitable induction motor D.C. generator set.
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116 views
1 answer
asked
Mar 20, 2018
by
anonymous

State any two applications of single phase autotransformer.
Last Answer : Applications of single phase auto transformers: 1) Give small boost to distribution cable to correct the voltage drop. 2) As auto transformer starter for induction motors. 3) As furnace supply ... . 5) In control equipment for single phase locomotives. 6) As dimmer in lighting circuits.
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52 views
1 answer
asked
Jan 8, 2021
by
anonymous

State any two conditions for parallel operation of 3-phase transformer.
Last Answer : Conditions for Parallel operation of 3 phase transformer 1) Voltage ratings of both the transformers must be identical. 2) Percentage or p.u. impedance should be equal in magnitude. 3) X/R ratio ... between primary & secondary voltages must be same. 6) Phase sequence on both sides must be same.
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51 views
1 answer
asked
Jan 8, 2021
by
anonymous
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Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application
Last Answer : Ans:
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52 views
1 answer
asked
Jan 8, 2021
by
anonymous

Define transformation ratio in terms of current and voltage.
Last Answer : (i) Transformation Ratio (K) is defined as the ratio of the primary current to the secondary current. (ii) Transformation Ratio (K) is defined as the ratio of the secondary voltage to the primary voltage.
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41 views
1 answer
asked
Jan 8, 2021
by
anonymous

Define: (i) Commercial efficiency of a transformer and (ii) All day efficiency of a transformer.
Last Answer : (i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day
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136 views
1 answer
asked
Jan 8, 2021
by
anonymous

A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.
Last Answer : Iron loss is dependent on voltage and independent of load. Hence iron loss at 75% of Load = Iron loss at full load = 2 kW
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104 views
1 answer
asked
Jan 8, 2021
by
anonymous

State any four properties of Ideal transformer.
Last Answer : Properties of Ideal transformer: 1) No losses (iron and copper losses), hence no temperature rise. 2) No magnetic leakage i.e (Coefficient of coupling between primary and secondary windings is unity) 3) Zero winding ... drop i.e. E1 = V1, E2 = V2 5) Efficiency 100 %. 6) Regulation 0 %.
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34 views
1 answer
asked
Jan 8, 2021
by
anonymous

a dc generator has a terminal voltage of 250V and an induced voltage of 262V when the generator is loaded. the brush drop is 1volt per brush and the armature resistance is 0.03 ohm ... reaction and determine the following: the load current the power of the load the percentage voltage regulation.
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13 views
0 answers
asked
Aug 3, 2021
by
yanga

A 4-pole, dc shunt motor working on 250V takes a current of 2A when running at no load on 1000 rpm. Calculate its back emf and speed at load if the motor takes 51A. Armature and shunt field resistance are 0.2Ω and 250Ω respectively
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14 views
0 answers

Describe the operation of shunt capacitor filter with the help of circuit diagram and waveforms.
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46 views
0 answers

Describe the operation of shunt capacitor filter with the help of circuit diagram and waveforms.
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5 views
0 answers

66 views
0 answers
asked
Jul 23, 2019
by
anonymous

State the use of shunt and series resistance used in extension of meter.
Last Answer : Use of shunt and series resistance: i) Use of shunt: To extend the range of Ammeter. ii) Use of series resistance: To extend the range of Voltmeter.
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88 views
1 answer
asked
Sep 6, 2018
by
anonymous

In which of the following transmission lines, the value of the Shunt admittance should be approximated to zero ? (A) A 66 kV 35 km long line (B) A 132 kV 200 km long line (C) A 220 kV 300 km long line (D) A 400 kV 500 km long line
Last Answer : In which of the following transmission lines, the value of the Shunt admittance should be approximated to zero ? (A) A 66 kV 35 km long line (B) A 132 kV 200 km long line (C) A 220 kV 300 km long line (D) A 400 kV 500 km long line
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523 views
1 answer
asked
May 8, 2018
by
anonymous

Shunt compensation in an EHV line is used to (A) Improve stability. (B) Improve the voltage profile. (C) Reduce the fault level. (D) Substitute for synchronous phase modifier.
Last Answer : Shunt compensation in an EHV line is used to Improve the voltage profile.
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5.3k views
1 answer
asked
May 8, 2018
by
anonymous

A shunt fault is characterized by (A) Increase in current, frequency and pf (B) Increase in current, reduction in frequency and pf (C) Increase in current and frequency, reduction in pf (D) Decrease in current and frequency
Last Answer : B
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1.0k views
2 answers
asked
Apr 28, 2018
by
anonymous
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Last Answer : The function of shunt in an ammeter is to by pass the current.
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462 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a manual shunt motor starter over load relay is connected in series and no volt relay in parallel with the load.
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76 views
1 answer
asked
Mar 20, 2018
by
anonymous
