Armature coil is short circuited by brushes when it lies?

by

1 Answer

Answer :

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

by

Related questions

Open circuited armature coil of a D.C. machine is?

Last Answer : Open circuited armature coil of a D.C. machine is identified by the scarring of the commutator segment to which open circuited coil is connected and indicated by a spark completely around the commutator.

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

Description : 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

The rapid wear of brushes takes place due to?

Last Answer : The rapid wear of brushes takes place due to abrasion from dust, excessive spring pressure, rough commutator bars, high mica insulation between com-mutation bars.

The number of brushes in a commutator depends on?

Last Answer : The number of brushes in a commutator depends on amount of current to be collected.

The material for commutator brushes is generally?

Last Answer : The material for commutator brushes is generally carbon.

Brushes of D.C. machines are made of?

Last Answer : Brushes of D.C. machines are made of carbon.

Copper brushes in D.C. machine are used?

Last Answer : Copper brushes in D.C. machine are used where low voltage and high currents are involved.

In lap winding, the number of brushes is always?

Last Answer : In lap winding, the number of brushes is always same as the number of poles.

If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will?

Last Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.

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.

The armature core of a D.C. generator is usually made of?

Last Answer : The armature core of a D.C. generator is usually made of silicon steel.

The demagnetising component of armature reaction in a D.C. generator?

Last Answer : The demagnetising component of armature reaction in a D.C. generator reduces generator e.m.f.

Armature reaction of an unsaturated D.C. machine is?

Last Answer : Armature reaction of an unsaturated D.C. machine is crossmagnetising.

The commutator segments are connected to the armature conductors by means of?

Last Answer : The commutator segments are connected to the armature conductors by means of copper lugs.

The resistance of armature winding depends on?

Last Answer : The resistance of armature winding depends on length of conductor, cross-sectional area of the conductor, number of conductors.

In a DC motor, it is important to place the brushes along ______

Description : In a DC motor, it is important to place the brushes along ______ A) Magnetic Neutral Axis B) Normal Geometric Axis C) Nominal Geometric Axis D) None of these

Last Answer : In a DC motor, it is important to place the brushes along Magnetic Neutral Axis

Brushes of DC machine are made up of ?

Description : Brushes of DC machine are made up of ?

Last Answer : Brushes of DC machine are made up of carbon.

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

Description : 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.

What is armature winding?

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

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

Description : 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

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance

Description : 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

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

Description : 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 

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

Description : 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

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

Description : 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 

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

Description : 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

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

Description : 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 ... ) 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

What is the effect of armature reaction?

Description : 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

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

Description : 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

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

Description : 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.

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

Description : 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.

When the armature of a D.C. motor rotates, e.m.f. induced is

Last Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

The armature voltage control of D.C. motor provides?

Last Answer : The armature voltage control of D.C. motor provides constant torque drive.

The armature torque of the D.C. shunt motor is proportional to?

Last Answer : The armature torque of the D.C. shunt motor is proportional to armature current.

In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be?

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.

In a A.C. series motor armature coils are usually connected to commutator?

Last Answer : In a A.C. series motor armature coils are usually connected to commutator through resistance.

In a synchronous motor, the armature current has large values for?

Last Answer : In a synchronous motor, the armature current has large values for high and low excitation.

The armature current of the synchronous motor?

Last Answer : The armature current of the synchronous motor has large values for low and high excitation.

Why is the armature of DC generator laminated?

Description : Why is the armature of DC generator laminated?

Last Answer : The armature of DC generator is laminated to reduce eddy current losses.

Armature control of DC motor

Description : Armature control of DC motor

Last Answer : Armature control of DC motor

What do you mean by coil?

Description : What do you mean by coil?

Last Answer : Ans. Having one or more turns connected in series is called coil.

State the function of overload coil and No volt coil in dc motor starter.

Description : State the function of overload coil and No volt coil in dc motor starter.

Last Answer : Function of Overload Coil: When DC motor is overloaded, the overload coil carries the overload current and produces strong magnetic field to attract a plunger, which short the terminals of ... dc motor is prevented from restarting automatically on recovery of supply without starter and protected.

Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Description : Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Last Answer : (i) Material used for Moving coil: Copper, Aluminum( some times)  (ii) Permanent magnets are made of special alloys such as :  Aluminum-Nickel-Cobalt (Alnicos)  Strontium-Iron  Neodymium-Iron-Boron  Samarium-Cobalt.

State the material used for moving coil and former for PMMC instruments.

Description : State the material used for moving coil and former for PMMC instruments. 

Last Answer : Material Used for Moving Coil and Former for PMMC Instruments:  Material used for moving coil: Copper  Material used for Former: Aluminium

The purpose of the restraining coil in a biased differential relay is

Description : The purpose of the restraining coil in a biased differential relay is  (A) To reduce CT saturation during fault.  (B) To increase the sensitivity of the relay.  (C) To match the transformation ratio.  (D) To limit the spill current through the relay during heavy external fault.

Last Answer : d

Permanent magnet moving coil instruments are used for

Description : Permanent magnet moving coil instruments are used for

Last Answer : PMME are mostly used for measuring voltage and current.

Peterson coil is used for :

Description : Peterson coil is used for :  (A) shunt compensation of lines (B) grounding of system neutral (B) reduce fault currents (D) connecting interconnected systems

Last Answer : Peterson coil is used for : grounding of system neutral

A moving coil of meter has 100 turns, and a length and depth of 10mm and 20mm respectively. It is positioned

Description : A moving coil of meter has 100 turns, and a length and depth of 10mm and 20mm respectively. It is positioned in a uniform radial flux density of 200 mT. The coil carrier current capacity is 50 mA. The torque on the coil is

Last Answer : A moving coil of meter has 100 turns, and a length and depth of 10mm and 20mm respectively. It is positioned in a uniform radial flux density of 200 mT. The coil carrier current capacity is 50 mA. The torque on the coil is 200µNm

A Peterson coil is ________

Description : A Peterson coil is ________ A) An arc generating coil B) An arc suppressing coil C) An arc inducing coil D) None of these

Last Answer : A Peterson coil is An arc suppressing coil

The self inductance of a coil can be measured using

Description : The self inductance of a coil can be measured using (A) Wien’s Bridge (B) Schering Bridge (C) Anderson’s Bridge (D) Wheatstone Bridge

Last Answer : The self inductance of a coil can be measured using Anderson’s Bridge