Answer :
The material for commutator brushes is generally carbon.
asked
Mar 20, 2018
by
anonymous
Answer :
In lap winding, the number of brushes is always same as the number of poles.
asked
Mar 20, 2018
by
anonymous
Answer :
Copper brushes in D.C. machine are used where low voltage and high currents are involved.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 21, 2018
by
anonymous
Answer :
Armature coil is short circuited by brushes when it lies along neutral axis.
asked
Mar 21, 2018
by
anonymous
Answer :
Brushes of D.C. machines are made of carbon.
asked
Mar 20, 2018
by
anonymous
Answer :
To avoid formation of grooves in the commutator of a D.C. machine the brushes of opposite polarity should track each other.
asked
Mar 21, 2018
by
anonymous
Answer :
In a commutator mica is harder than copper.
asked
Mar 20, 2018
by
anonymous
Answer :
The insulating material used between the commutator segments is normally mica.
asked
Mar 20, 2018
by
anonymous
Description : Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is (A) 48 (B) 24 (C) 192 (D) 96
Answer :
Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is 24
asked
Apr 28, 2018
by
anonymous
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
Answer :
In a DC motor, it is important to place the brushes along Magnetic Neutral Axis
asked
Apr 29, 2018
by
anonymous
Description : Brushes of DC machine are made up of ?
Answer :
Brushes of DC machine are made up of carbon.
asked
Mar 3, 2018
by
anonymous
Description : The function of a brush and commutator arrangement in a dc motor is to (1) produce unidirectional torque (2) produce unidirectional current in the armature (3) help in changing the direction of rotation of the armature (4) reduce sparking
Answer :
The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque
asked
Apr 29, 2018
by
anonymous
Answer :
Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.
asked
Mar 20, 2018
by
anonymous
Answer :
In a A.C. series motor armature coils are usually connected to commutator through resistance.
asked
Mar 20, 2018
by
anonymous
Description : State the function of commutator in DC generator and name the material used for commutator.
Answer :
Function of Commutator: Commutator converts AC induced in armature winding into DC for external load. Material: i) Commutator segments are made up of Copper. ii) Commutator segments are insulated from each other by Mica.
asked
Jul 27, 2019
by
anonymous
Description : Which of the following does not have a commutator? A) Dynamo B) Induction motor C) Universal motor D) None of these
Answer :
Which of the following does not have a commutator? A) Dynamo B) Induction motor C) Universal motor D) None of these
asked
Apr 29, 2018
by
anonymous
Answer :
In D.C. generators, the brushes on commutator remain in contact with conductors which lie under interpolar region.
asked
Mar 20, 2018
by
anonymous
Description : Increasing the number of turns of wire on the secondary of a transformer will (A) Decrease the secondary current (B) Increase the primary current (C) Have no effect on the secondary current (D) Increase the secondary current
Answer :
Increasing the number of turns of wire on the secondary of a transformer will Decrease the secondary current
asked
May 8, 2018
by
anonymous
Description : A number of forces acting at a point will be in equilibrium if?
Answer :
A number of forces acting at a point will be in equilibrium if sum of resolved parts in any two per-pendicular directions are both zero.
asked
Mar 22, 2018
by
anonymous
Description : What is the maximum number of circuit breakers in a panel?
Answer :
It depends on that which type of panel is this.
asked
Mar 10, 2018
by
anonymous
Description : What is the choice of size and number of generator units in interconnected power system?
Answer :
Choice of Size and Number of Generating Units: 1. The size/rating and number of generating units in such way that they approximately match with the load curve as closely as possible. 2. In ... , if power plant is connected to grid system then generating unit of higher capacity can be installed.
asked
Sep 7, 2018
by
anonymous
Description : Then number of T-states of the instruction STA in 8085 microprocessor is A) 10 B) 12 C) 13 D) 16
Answer :
Then number of T-states of the instruction STA in 8085 microprocessor is 13
asked
Jun 18, 2018
by
anonymous
Description : The number of terminals present in IGBT is A) 2 B) 3 C) 4 D) 5
Answer :
The number of terminals present in IGBT is 3
asked
Jun 18, 2018
by
anonymous
Description : The number of electrons in the outer most orbit of carbon atom is?
Answer :
The number of electrons in the outer most orbit of carbon atom is 4.
asked
Mar 25, 2018
by
anonymous
Description : What are the number of valence electrons of atoms in semiconductor?
Answer :
There are four valence electrons in the atom of a semiconductor.
asked
Mar 9, 2018
by
anonymous
Description : The number of loop equations required to completely analysing a network comprising of 8 independent branches and 6 nodes including the reference node shall be A) 3 B) 2 C) 4 D) 5
Answer :
The number of loop equations required to completely analysing a network comprising of 8 independent branches and 6 nodes including the reference node shall be 3
asked
Jun 18, 2018
by
anonymous
Description : A connected graph has ‘5’ number of branches and ‘4’ number of nodes. It's rank is A) 1 B) 2 C) 3 D) 4
Answer :
A connected graph has ‘5’ number of branches and ‘4’ number of nodes. It's rank is 3
asked
Jun 18, 2018
by
anonymous
Description : lt the length, number of turns and area of a coil are doubled, the inductance of the coil
Answer :
lt the length, number of turns and area of a coil are doubled, the inductance of the coil is quadrupled
asked
Apr 26, 2018
by
anonymous
Description : The number of independent equations to solve a network is equal to?
Answer :
The number of independent equations to solve a network is equal to the number of chords.
asked
Mar 25, 2018
by
anonymous
Description : What is the Gray code word for the binary number 101011? (1) 101011 (2) 110101 (3) 011111 (4) 111110
Answer :
What is the Gray code word for the binary number 101011? (1) 101011 (2) 110101 (3) 011111 (4) 111110
asked
Apr 30, 2018
by
anonymous
Description : The number of poles of 8/6 stepper motor can be :
Answer :
The number of poles of 8/6 stepper motor can be : 4
asked
Apr 30, 2018
by
anonymous
Description : Build using minimum number of CMOS gates. Three input NAND gate. Two input NOR gate Three input NOR gate Two input AND gate Two input OR gate
Answer :
Three input NAND gate. Two input NOR gate Three input NOR gate Two input AND gate Two input OR gate
asked
Mar 21, 2018
by
anonymous
Answer :
In case of D.C. machine winding, number of commutator segments is equal to number of armature coils.
asked
Mar 20, 2018
by
anonymous
Description : In a DC shunt generator working on load, the brushes are moved forward in the direction of rotation, as a result of this, commutation will (a) Improve but terminal voltage will fall (b) Worsen and terminal voltage will fall (c) Improve and terminal voltage will rise (d) worsen and terminal voltage will rise
Answer :
In a DC shunt generator working on load, the brushes are moved forward in the direction of rotation, as a result of this, commutation will Improve but terminal voltage will fall
asked
May 13, 2018
by
anonymous
Answer :
Commutator brushes are made up of carbon.
asked
Sep 18, 2017
by
anonymous
Answer :
If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be crossmagnetisation as well as demagnetising.
asked
Mar 20, 2018
by
anonymous
Answer :
The resistance of armature winding depends on length of conductor, cross-sectional area of the conductor, number of conductors.
asked
Mar 20, 2018
by
anonymous
Answer :
The commutator segments are connected to the armature conductors by means of copper lugs.
asked
Mar 20, 2018
by
anonymous
Description : In the indexed scheme of blocks to a file, the maximum possible size of the file depends on: (A) The number of blocks used for index, and the size of index (B) Size of Blocks and size of Address (C) Size of Index (D) Size of Block
Answer :
(A) The number of blocks used for index, and the size of index
Description : If S1 is total number of modules defined in the program architecture, S3 is the number of modules whose correct function depends on prior processing then the number of modules not dependent on prior processing is: (A) 1 + S3/S1 (B) 1 - S3/S1 (C) 1 + S1/S3 (D) 1 - S1/S3
Answer :
(B) 1 - S3/S1
Description : The number of brushes in a 6-pole double-layer lap wound dc machine is (A) 8 (B) 6 (C) 4 (D) 2
asked
Jun 4, 2018
by
anonymous
Description : The supply of labour in the market depends on (1) the proportion of the population in the labour force (2) the number of person hours put in by each person (3) the size of population (4) All the above
Answer :
All the above
asked
Mar 20, 2018
by
anonymous
Description : In a 6-pole wave wound dc machine the number of conductors is 70. The back pitch and commutator segments, respectively, are (A) 11and 35 (B) 12 and 34 (C) 13 and 35 (D) 14 and 34
asked
Jun 4, 2018
by
anonymous
Description : A bomb at rest explodes into a large number of tiny fragments. The total momentum of all the fragments (1) is zero (2) depends on the total mass of all the fragments (3) depends on the speeds of various fragments (4) is infinity
Answer :
is zero
Description : The total magnetic moment 1. is called saturation magnetization. 2. depends on the number of magnetic dipoles per unit volume, the instant electric current and the area of the current loop. Which of the above statements is/are correct ?
Answer :
depends on the number of magnetic dipoles per unit volume, the instant electric current and the area of the current loop
asked
Apr 25, 2018
by
anonymous
Answer :
In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.
asked
Mar 20, 2018
by
anonymous
Description : The chemical bahaviour of an atom depends upon (1) the number of protons in its nucleus (2) the number of neutrons in the nucleus (3) the number of electrons orbiting around the nucleus (4) the number of nucleons in the nucleus
Answer :
the number of electrons orbiting around the nucleus
Description : For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f. ?
Answer :
Wave winding
asked
Mar 20, 2018
by
anonymous