Recent questions tagged armature

asked May 7, 2020 by anonymous

Define armature reaction in an alternator. Explain the effect of armature reaction at various P.F. of loads of alternator.

Last answer: Armature Reaction: The effect of armature flux on main flux is called as armature reaction. Armature Reaction at Various Power Factors: When armature is loaded, the armature flux modifies ... lagging p.f. For capacitive loads the effect of flux is partly distorting and partly strengthening.

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145 views 1 answer

asked Jul 27, 2019 by anonymous

What is armature winding?

Last answer: It is the wire wound around a aluminium metal it is found commonly in transformers or motors

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83 views 1 answer

asked May 8, 2018 by anonymous

A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2

A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is

Last answer: A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is 0.87

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69 views 1 answer

asked May 3, 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

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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175 views 1 answer

asked May 1, 2018 by anonymous

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation,

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator

Last answer: In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator

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325 views 1 answer

asked May 1, 2018 by anonymous

In dc machines, the armature windings are placed on the rotor because of the necessity for

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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189 views 2 answers

asked Apr 30, 2018 by anonymous

In a 3 -phase alternator, if there is only magnetizing armature reaction, the load is :

In a 3 -phase alternator, if there is only magnetizing armature reaction, the load is : (A) capacitive (B) inductive (C) resistive (D) inductive and resistive

Last answer: In a 3 -phase alternator, if there is only magnetizing armature reaction, the load is : capacitive

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75 views 1 answer

asked Apr 29, 2018 by anonymous

The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole)

The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) (A) has q -axis current only (B) has d -axis current only (C) has both d and q axis currents (D) cannot be divided between q and d axis currents

Last answer: The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) has d -axis current only

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115 views 1 answer

asked Apr 29, 2018 by anonymous

The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors

The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is (1) 1000V (2) 100V (3) 600V (4) 10,000V

Last answer: The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is 1000V

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173 views 1 answer

asked Apr 29, 2018 by anonymous

Aluminium is not used as winding wire for the armature of a dc machine because

Aluminium is not used as winding wire for the armature of a dc machine because (1) aluminium has low resistivity (2) a large winding space is taken by aluminium conductors and creates jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper

Last answer: Aluminium is not used as winding wire for the armature of a dc machine because (2) a large winding space is taken by aluminium conductors and creates jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper

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494 views 1 answer

asked Apr 29, 2018 by anonymous

What is the effect of armature reaction?

What is the effect of armature reaction? A) Demagnetization of the main field B) Demagnetization of the brushes C) Cross-magnetization of the brushes D) None of these

Last answer: What is the effect of armature reaction? A) Demagnetization of the main field B) Demagnetization of the brushes C) Cross-magnetization of the brushes D) None of these

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207 views 1 answer

asked Apr 28, 2018 by anonymous

The armature reaction in a synchronous generator supplying leading power factor load is

The armature reaction in a synchronous generator supplying leading power factor load is (A) magnetizing (B) demagnetizing (C) demagnetizing and cross-magnetizing (D) magnetizing and cross-magnetizing

Last answer: The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing

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49 views 1 answer

asked Mar 26, 2018 by anonymous

The induced e.m.f. in the armature conductors of a d.c. motor is?

Last answer: The induced e.m.f. in the armature conductors of a d.c. motor is sinusoidal.

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338 views 1 answer

asked Mar 26, 2018 by anonymous

The normal value of the armature resistance of a d.c. motor is?

Last answer: The normal value of the armature resistance of a d.c. motor is 0.5.

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771 views 1 answer

asked Mar 21, 2018 by anonymous

Armature reaction in a generator results in?

Last answer: Armature reaction in a generator results in demagnetisation of leading pole tip and magnetisation of trailing pole tip.

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81 views 1 answer

asked Mar 21, 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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131 views 1 answer

asked Mar 21, 2018 by anonymous

Armature coil is short circuited by brushes when it lies?

Last answer: Armature coil is short circuited by brushes when it lies along neutral axis.

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127 views 1 answer