State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.
Last Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows: 1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine
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1 answer
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May 7, 2020
by
anonymous

Last Answer : The power factor of a single-phase induction motor is usually lagging.
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189 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.
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91 views
1 answer
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Mar 20, 2018
by
anonymous

Brake test on DC series 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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298 views
2 answers
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Apr 21, 2020
by
anonymous

Describe the reason of using dc series motor for electric trains.
Last Answer : Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up ... torque - speed characteristics of DC series motors match, these motors are suitable for electric trains
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142 views
1 answer
asked
Sep 18, 2018
by
anonymous
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In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :
Last Answer : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075
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109 views
1 answer
asked
Apr 29, 2018
by
anonymous

Last Answer : In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.
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503 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The speed of a D.C. series motor is inversely proportional to the armature current.
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114 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : A D.C. series motor is that which has its field winding consisting of thick wire and less turns.
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82 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The direction of rotation of a D.C. series motor can be changed by interchanging field terminals.
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185 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.
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136 views
1 answer
asked
Mar 20, 2018
by
anonymous

What are the advantages of DC series motor?
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92 views
0 answers
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Mar 15, 2018
by
anonymous

Why dc series motor should not be started at no load?
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629 views
0 answers
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Mar 15, 2018
by
anonymous

Why a dc series motor has a high starting torque?
Last Answer : motor
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86 views
1 answer
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Mar 15, 2018
by
anonymous

At which time power factor of the induction motor is low?
Last Answer : The power factor of the inducction motor is low at the time of starting as compare to while the induction motor is running.
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150 views
1 answer
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Mar 3, 2018
by
anonymous

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
Last Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.
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169 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : An induction motor has relatively high power factor at near full load.
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91 views
1 answer
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Mar 20, 2018
by
anonymous

If the load of the normally excited synchronous motor is increased the power factor will?
Last Answer : If the load of the normally excited synchronous motor is increased the power factor will become lagging.
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150 views
1 answer
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Mar 18, 2018
by
anonymous

The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Last Answer : The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
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162 views
1 answer
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Mar 18, 2018
by
anonymous

If the field of synchronous motor is under excited, power factor will be?
Last Answer : If the field of synchronous motor is under excited, power factor will be lagging.
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483 views
1 answer
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Mar 18, 2018
by
anonymous

How can we improve power factor using synchronous motor?
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78 views
0 answers
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Mar 15, 2018
by
anonymous

Last Answer : Yes, we can make the power factor of synchronous motor leading by adjusting its excitation.
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109 views
1 answer
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Mar 6, 2018
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
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Jul 5, 2019
by
anonymous
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The power factor of a D.C. circuit is always?
Last Answer : The power factor of a D.C. circuit is always unity.
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219 views
1 answer
asked
Mar 25, 2018
by
anonymous

Last Answer : In A.C. series motor compensating winding is employed to reduce sparking at the brushes.
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145 views
1 answer
asked
Mar 20, 2018
by
anonymous

Is the power line voltage available in our homes a dc or an ac voltage?
Last Answer : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.
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5.2k views
1 answer
asked
Jun 29, 2019
by
anonymous

We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be
Last Answer : We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be 2.4 kOhm
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149 views
1 answer
asked
May 8, 2018
by
anonymous

Last Answer : (b) Clostridium butylicum Lipase Removal of oil stains
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107 views
1 answer
asked
Mar 20, 2018
by
anonymous
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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

Two 100W, 200V lamps are connected in series across a 200V supply. The total power consumed by each lamp will be in Watts
Last Answer : 4800
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444 views
2 answers
asked
May 8, 2018
by
anonymous

Last Answer : In a A.C. series motor armature coils are usually connected to commutator through resistance.
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161 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : The primary reason for low power factor is supply system is due to installation of induction motors.
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115 views
1 answer
asked
Mar 20, 2018
by
anonymous

A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the
Last Answer : A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the C only
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2.0k views
1 answer
asked
Apr 29, 2018
by
anonymous

Last Answer : When two D.C. series motors are connected in parallel, the resultant speed is normal speed.
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378 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a low power factor wattmeter the compensating coil is connected in series with pressure coil.
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487 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a low power factor wattmeter the pressure coil is connected to the load side of the current coil.
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374 views
1 answer
asked
Mar 21, 2018
by
anonymous

The loop equation for a series RLC circuit gives
Last Answer : The loop equation for a series RLC circuit gives
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124 views
1 answer
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Apr 2, 2020
by
anonymous
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Source transformation Replace the circuit with voltage source in series with a single resistor
Last Answer : Source transformation Replace the circuit with voltage source in series with a single resistor
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247 views
1 answer
asked
Mar 21, 2020
by
anonymous

Last Answer : If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by eddy currents.
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102 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : The value of starting capacitor of a fractional horse power motor will be 300 uF .
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98 views
1 answer
asked
Mar 20, 2018
by
anonymous

Write two applications of D.C. series motor.
Last Answer : The applications of D.C. series motor: 1. Cranes 2. Hoists 3. Trolley and cars 4. Conveyors 5. For traction work i.e. electric locomotives 6. Elevator 7. Air compressor
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117 views
1 answer
asked
Apr 27, 2020
by
anonymous

Last Answer : For high value of diversity factor, a power station of given installed capacity will be in a position to supply more number of consumers.
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169 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If equalising bar is connected to the 2 DC generators the current will be equal in 2 generators irrespective of parallel connection so that we connect equaliser bar
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165 views
2 answers
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Mar 21, 2018
by
anonymous

Last Answer : During rheostat braking of D.C. series motors motor is run as a generator.
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85 views
1 answer
asked
Mar 20, 2018
by
anonymous

In case of conductively compensated D.C. series motors, the compensating winding is provided?
Last Answer : In case of conductively compensated D.C. series motors, the compensating winding is provided in series with armature winding.
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97 views
1 answer
asked
Mar 20, 2018
by
anonymous
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State the effects of low power factor on efficiency and voltage regulation of short transmission lines.
Last Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor)
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357 views
1 answer
asked
May 22, 2020
by
anonymous
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Draw the block diagram of regulated power supply, explain function of each block and draw waveforms of each stage.
Last Answer : 1. A step down transformer 2. A rectifier 3. A filter 4. A regulator Operation of Regulated Power Supply:- Step Down Transformer:- A step down transformer will ... regulator. A regulator will maintain the output constant even when changes at the input or any other changes occur.
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2.0k views
3 answers
asked
May 2, 2020
by
anonymous

Last Answer : At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.
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130 views
1 answer
asked
Mar 20, 2018
by
anonymous

An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS
Last Answer : An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS
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4.0k views
1 answer
asked
Jun 18, 2018
by
anonymous

Is more power dissipated in series or parallel?
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67 views
0 answers
asked
Mar 10, 2018
by
anonymous
