Burning out of windings is due to?

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asked Mar 20, 2018 by anonymous

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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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184 views 2 answers

asked Apr 29, 2018 by anonymous

In a DC generator the windings of interpoles are connected :

In a DC generator the windings of interpoles are connected : (A) in series with main field winding, to create a pole,of same polarity as the main pole ahead in the direction of rotation. (B) in series with main field winding, to create a pole of opposite polarity as the main pole ahead in the direction of ... in the direction of rotation. (D) in series with the armature winding, to create a pole of opposite polarity as the main pole ahead in the direction of rotation.

Last answer: In a DC generator the windings of interpoles are connected : in series with the armature winding, to create a pole of same polarity as the main pole ahead in the direction of rotation.

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64 views 1 answer

asked Mar 20, 2018 by anonymous

Compensating windings are used in D.C. generators?

Last answer: Compensating windings are used in D.C. generators to neutralise the cross-magnetising effect of the armature reaction.

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101 views 1 answer

asked Jun 17, 2018 by anonymous

Which statement out of the following is a wrong statement with regard to Induction motor?

Which statement out of the following is a wrong statement with regard to Induction motor? A) Auto-transformer starter is costlier to “direct on line” (DOL) starter B) DOL starter is used for motors up to 5 horse power only C) Auto transformer starter is used for motors up to 20 horse power only D) Star delta starter connects the motor first in delta at the time of starting then in star for running

Last answer: Which statement out of the following is a wrong statement with regard to Induction motor? A) Auto-transformer starter is costlier to direct on line (DOL) starter B) DOL starter is used for ... delta starter connects the motor first in delta at the time of starting then in star for running

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55 views 1 answer

asked May 22, 2018 by anonymous

Electrical fault between two windings of same phase of a generator having double star winding can be

Electrical fault between two windings of same phase of a generator having double star winding can be detected by the following protection in a generator:

Last answer: Electrical fault between two windings of same phase of a generator having double star winding can be detected by the following protection in a generator: inter turn fault protection

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50 views 1 answer

asked Mar 20, 2018 by anonymous

Overheating of relay contacts or contact born out is due to?

Last answer: Overheating of relay contacts or contact born out is due to slow making and breaking of load circuit contacts, foreign matter on the contact surface, too low contact pressure.

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92 views 1 answer

asked 1 day ago by anonymous

Natural sources of air pollution are (1) Forest fires (2) Volcanic eruptions (3) Dust storm (4) Smoke from burning dry leaves

Last answer: Volcanic eruptions

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2 views 1 answer

asked May 20, 2018 by anonymous

A cylindrical rotor synchronous motor is switched on to the supply with its field windings shorted on

A cylindrical rotor synchronous motor is switched on to the supply with its field windings shorted on themselves, the motor will . A) Not start B) Start but will not run at synchronous speed C) Start as an induction motor and then run as a synchronous motor D) Start and run as a synchronous motor

Last answer: A cylindrical rotor synchronous motor is switched on to the supply with its field windings shorted on themselves, the motor will Start but will not run at synchronous speed

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205 views 1 answer

asked May 12, 2018 by anonymous

Fractional pitch windings are used in DC machines to

Fractional pitch windings are used in DC machines to (A) Reduce copper losses (B) Improve cooling (C) Increase the generated emf (D) Reduce sparking

Last answer: Fractional pitch windings are used in DC machines to Reduce sparking

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82 views 1 answer

asked May 17, 2018 by anonymous

In case of split phase motor, the phase shift between currents in the two windings is around

In case of split phase motor, the phase shift between currents in the two windings is around A) 30° B) 70° C) 90° D) 120°

Last answer: In case of split phase motor, the phase shift between currents in the two windings is around 30°

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108 views 1 answer

asked May 13, 2018 by anonymous

In a transformer, low voltage winding is placed near the core in case of concentric windings so

In a transformer, low voltage winding is placed near the core in case of concentric windings so as to 1. Reduce the leakage flux 2. Reduce the insulation requirement 3. Reduce the risk of voltage shock in case of insulation breakdown 4. Reduce the core loss From these, the correct answer is (a) 1, 2, 3 (b) 2, 3, 4 (c) 1, 2, 3, 4 (d) 2, 3

Last answer: In a transformer, low voltage winding is placed near the core in case of concentric windings so as to 1. Reduce the leakage flux 2. Reduce the insulation requirement 3. Reduce the risk of voltage shock in case of insulation breakdown 4. Reduce ... ) 1, 2, 3 (b) 2, 3, 4 (c) 1, 2, 3, 4 (d) 2, 3

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asked Jun 4, 2018 by anonymous

Full load current of an Induction motor is 20 Ampere. The no-load current may be expected to be:

Full load current of an Induction motor is 20 Ampere. The no-load current may be expected to be: A) 25 Ampere to 28 Ampere B) 15 Ampere to 18 Ampere C) 11 Ampere to 14 Ampere D) 6 Ampere to 10 Ampere

Last answer: D

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asked May 25, 2018 by anonymous

The effect of increasing the length of air gap in an induction motor is to increase the

The effect of increasing the length of air gap in an induction motor is to increase the (a) power factor (b) speed (c) magnetising current (d) air gap flux

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125 views 0 answers

asked May 25, 2018 by anonymous

The ratio of rotor output to rotor input in an induction motor is 0.96. The slip of the motor is

The ratio of rotor output to rotor input in an induction motor is 0.96. The slip of the motor is (a) 0.04% (b) 4% (c) 6% (d) 12%

Last answer: The ratio of rotor output to rotor input in an induction motor is 0.96. The slip of the motor is 4%

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225 views 1 answer

asked Mar 20, 2018 by anonymous

When a D.C. series motor is connected to A.C. supply, the power factor will be low because of?

Last answer: When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.

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90 views 1 answer

asked Mar 20, 2018 by anonymous

The running winding of a single phase motor on testing with meggar is found to be ground...

The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be?

Last answer: The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be at the slot edge where coil enters or comes out of the slot.

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84 views 1 answer

asked Mar 20, 2018 by anonymous

In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to?

Last answer: In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to improve power factor.

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420 views 1 answer

asked 5 hours ago by anonymous

If an industry is characterised by economies of scale then (1) barriers to entry are not very large (2) long run unit costs of production decreases as the quantity the firm produces increases (3) capital requirement are small due to the efficiency of the large scale operation (4) the costs of entry into the market are likely to be substantial

Last answer: long run unit costs of production decreases as the quantity the firm produces increases

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1 view 1 answer

asked 2 days ago by anonymous

Ozone layer is formed due to reactions of : (1) oxygen and ultraviolet rays (2) carbon dioxide and layers of atmosphere (3) cosmic rays and layers of atmosphere (4) infrared rays and ultraviolet rays

Last answer: oxygen and ultraviolet rays

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3 views 1 answer

asked 2 days ago by anonymous

Atmospheric pressure exerted on earth is due to : (1) rotation of earth (2) revolution of earth (3) gravitational pull (4) uneven heating of earth

Last answer: gravitational pull

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3 views 1 answer

asked 2 days ago by anonymous

Uneven distribution of insolation on the earth is mainly due to the (1) spherical shape of the earth (2) distribution of land and water (3) direction of the winds (4) presence of pressure belts

Last answer: spherical shape of the earth

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7 views 1 answer

asked 2 days ago by anonymous

Rift Valley is formed (1) between two anticlines (2) between two faults (3) erosion of synclinal basin (4) due to volcanic eruption

Last answer: between two faults

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8 views 1 answer

asked 4 days ago by anonymous

Hanging Valley is formed due to the action of (1) Glacier (2) River (3) Ocean (4) Wind

Last answer: Glacier

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asked 5 days ago by anonymous

A bike starts with a speed of 60 km/hr at 8a.m. Due to the problem in engine it reduces its speed as 20 km/hr for every 1 hour. After 9 am, the time taken to covers 15 km is: a) 13 minutes and 20 seconds b) 15 minutes and 09 seconds c) 18 minutes and 15 seconds d) 22 minutes and 30 seconds

Last answer: D Initial speed of the bike= 60 km/hr Due to engine problem, speed is reduced to 20km for every 1 hour Speed of the car at 9 am = (60 - 20) = 40km/hr Time to cover 15 km at 40 km/hr = ... = 22 minutes + 1/2 minutes = 22 minutes + 1/2 x 60 seconds = 22 minutes and 30 seconds.

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3 views 1 answer

asked 6 days ago by anonymous

A leak in the bottom of a bunker can empty the full bunker in 4 hrs. An inlet pump fills water at the rate of 3 litres a min. when the bunker is full, the inlet is opened and due to the leak, the bunker is empty in 6 hrs. How many litres does the bunker field? A) 1160 litrs B) 1610 litres C) 2160 litres D) 2610 litres

Last answer: C Work done by the inlet in 1 hr = (1/4 – 1/6) = (3-2/12) = 1/12 Work done by the inlet in 1 min = 1/12 * 1/60 = 1/720 Volume of 1/720 part = 3 litres Volume of whole = (720 * 3 )=2160 litres.

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asked 6 days ago by anonymous

Two taps P and Q can fill a cistern in 24 min and 32 min respectively. Both the taps are opened together for a certain time but due to some obstruction the flow of water was restricted to 7/4 of full flow in tap P and 5/3 of full in tap Q. This obstruction is removed after some time and cistern is now filled in 6min from that moment. How long was it before the full flow. A) 8 min B) 3 min C) 5.6 min D) 4.5 min

Last answer: D Let the obstruction remain for X min. Hence, Part of cistern filled in X min + part of cistern filled in 6 min = full cistern [(7X/4*24)+(5X/3*32)]+[(6/24)+(6/32)] = 1 (12X/96)+(7/16) = 1 12x/96=9/16 Thus, X = 4.5 min.

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asked 6 days ago by anonymous

A tank can be filled by an inlet tap at the rate of 8 litres per minute. A leak in the bottom of a tank can empty the full tank in 16 hours. When the tank is full, the inlet is opened and due to the leak, the tank is empty in 80 hours. How many litres does the tank hold? A) 8000 litre B) 9560 litre C) 8525 litre D) 9600 litre

Last answer: D Part emptied by the leak in 1 hour = 1/16 part filled by (leak & inlet open) in 1 hour = 1/80 Part filled by the inlet tap in 1 hour = 1/16 – 1/80 = 1/20 Inlet tap fills the tank in = 20 hours Inlet tap fills water at the rate of 8 litres a minute. Capacity of tank = 20 * 60 * 8= 9600 litre

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asked 6 days ago by anonymous

A tap can fill a cistern in 11hours, but due to a leakage it took 13hours to fill the cistern. If the cistern is full, in what time will the cistern become empty due to leakage ? A) 73.30hrs B) 77.50hrs C) 71.5 hrs D) 72.30hrs E) None of these

Last answer: C 1/11-1/13 = 13-11/143 =>2/143 =>1/71.5 =>71.5hours

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4 views 1 answer

asked Jan 10 by anonymous

A students maks were wrongly entered as 72 instead of 52. Due to that the average marks for the class got increased by half. The number of students in the class is. A) 50 B) 56 C) 46 D) 40

Last answer: D) Let there be y students in the class Total increase in marks = y *1/2 = y/2 Therefore y/2 = (72 – 52) y/2 = 20 y = 40

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3 views 1 answer

asked Dec 2, 2020 by anonymous

Suggest the type of joints in concrete when it is likely to increase in volume due to temperature change. Explain it and draw its neat sketch.

Last answer: When it is likely to increase in volume due to temperature change expansion joint is constructed. i. Expansion joints are provided by keeping a gap between panels of concrete and later sealing it ii. ... cotton and finally such joint is sealed using sealants like wood, thermocol or bitumen.

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26 views 1 answer

asked Jul 11, 2020 by anonymous

Explain the error occurred due to pressure coil inductance of electrodynamometer type wattmeter. How this error is compensated?

Last answer: For power measurement assume that the pressure coil of wattmeter is purely restitive. Hence current taken by pressure coil Ipc is in phase with voltage across the pressure coil Vpc ... inductive reactance XL the pressure coil circuit is made purely resistive and the error is eliminated.

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217 views 1 answer

asked Jun 14, 2018 by anonymous

Power transmitted through a pipe is maximum when the loss of head due to friction is :

Power transmitted through a pipe is maximum when the loss of head due to friction is : (A) one-half of the total head supplied (B) one-third of the total head supplied (C) one-fourth of the total head supplied (D) zero

Last answer: Power transmitted through a pipe is maximum when the loss of head due to friction is : one-third of the total head supplied

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45 views 1 answer

asked Jun 14, 2018 by anonymous

The ratio of maximum displacement of the forced vibration to the deflection due to static force is known as :

The ratio of maximum displacement of the forced vibration to the deflection due to static force is known as : (A) Damping Factor (B) Damping Coefficient (C) Logarithmic Decrement (D) Magnification Factor

Last answer: The ratio of maximum displacement of the forced vibration to the deflection due to static force is known as : Magnification Factor

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115 views 1 answer

asked Jun 4, 2018 by anonymous

The operation of the relay which is most affected due to arc resistance is

The operation of the relay which is most affected due to arc resistance is A) Mho relay B) Reactance relay C) Impedance relay D) All are equally affected

Last answer: The operation of the relay which is most affected due to arc resistance is Mho relay

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341 views 2 answers

asked May 26, 2018 by anonymous

In an AC transmission line difference in phase of voltage at two ends of the line is due to

In an AC transmission line difference in phase of voltage at two ends of the line is due to (a) System voltage (b) Insulators (c) Resistance of line (d) Reactance of line

Last answer: reactance of line

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2.7k views 1 answer

asked May 25, 2018 by anonymous

The d.c. resistance of a conductor due to skin effect is

The d.c. resistance of a conductor due to skin effect is (a) unchanged (b) decreased (c) increased (d) infinite

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72 views 0 answers

asked May 17, 2018 by anonymous

The property of sand due to which the sand grains stick together, is called

The property of sand due to which the sand grains stick together, is called 1. Collapsibility 2. Permeability 3. Cohesiveness 4. Adhesiveness

Last answer: The property of sand due to which the sand grains stick together, is called Cohesiveness

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131 views 1 answer

asked May 16, 2018 by anonymous

The presence of alkali oxides in alumino silicate ceramics is likely to result in dielectric breakdown due to

The presence of alkali oxides in alumino silicate ceramics is likely to result in dielectric breakdown due to (A) Polarization (B) Conductivity (C) Structural homogeneties (D) Ionization

Last answer: The presence of alkali oxides in alumino silicate ceramics is likely to result in dielectric breakdown due to Conductivity

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41 views 1 answer

asked May 15, 2018 by anonymous

In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is

In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is (a) equal to the line frequency (b) double the line frequency (c) 4 times the line frequency (d) not related to the line frequency

Last answer: In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is double the line frequency

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40 views 1 answer

asked May 13, 2018 by anonymous

The slight curvature at the lower end of the O.C.C. of a self-excited dc generator is due to

The slight curvature at the lower end of the O.C.C. of a self-excited dc generator is due to 1. residual pole flux 2. high armature speed 3.magnetic inertia 4. high field circuit resistance

Last answer: The slight curvature at the lower end of the O.C.C. of a self-excited dc generator is due to magnetic inertia

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316 views 1 answer

asked Apr 30, 2018 by anonymous

The skin effect in conductors is due to non uniform distribution of current in it and major portion of current is

The skin effect in conductors is due to non uniform distribution of current in it and major portion of current is near the _______ of conductor. (1) Surface (2) Center (3) Complete cross section area (4) Axis

Last answer: The skin effect in conductors is due to non uniform distribution of current in it and major portion of current is near the Surface of conductor.

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181 views 1 answer

asked Apr 25, 2018 by anonymous

In induction type directional over current relay the driving torque is due to interaction of magnetic fields

In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from (A) current in the potential coil (B) both voltage and current in the relay windings (C) directional element and non-directional element (D) non-directional element and the trip circuit

Last answer: In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from directional element and non-directional element

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71 views 1 answer

asked Apr 14, 2018 by anonymous

Production of heat due to electric current is related to

Production of heat due to electric current is related to . (A) Ohm's law (B) Joule's law (C) Kelvin's law (D) Maxwell's law

Last answer: production of heat due to current in a conductor ohm's law .

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97 views 1 answer

asked Apr 9, 2018 by anonymous

Frequency stability of crystal oscillator is due to its...

Frequency stability of crystal oscillator is due to its A) Low Q B) Low loss C) High feed back D) High bandwidth

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40 views 0 answers

asked Mar 29, 2018 by anonymous

The random motion of holes and free electrons due to thermal agitation is called ……….

Last answer: The random motion of holes and free electrons due to thermal agitation is called Diffusion.

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179 views 1 answer

asked Mar 28, 2018 by anonymous

Surface resistance of an insulating material is reduced due to the

Last answer: Surface resistance of an insulating material is reduced due to the smoky and dirty atmosphere, humidity in the atmosphere.

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56 views 1 answer

asked Mar 27, 2018 by anonymous

The transient response of a system is mainly due to?

Last answer: The transient response of a system is mainly due to stored energy.

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111 views 1 answer

asked Mar 25, 2018 by anonymous

Heat in a conductor is produced on the passage of electric current due to?

Last answer: Heat in a conductor is produced due to frictional collision of electrons flow as they conduct current.

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184 views 1 answer

asked Mar 22, 2018 by anonymous

The weight of a body is due to?

The weight of a body is due to

Last answer: The weight of a body is due to gravitational force of attraction towards the center of the earth.

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66 views 1 answer

asked Mar 20, 2018 by anonymous

The primary reason for low power factor is supply system is due to installation of?

Last answer: The primary reason for low power factor is supply system is due to installation of induction motors.

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84 views 1 answer

anonymous · Answer 1 · 2018-03-20T19:03:17+0000

answered Mar 20, 2018 by anonymous

Burning out of windings is due to short circuited capacitor.

Burning out of windings is due to?

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