In a universal motor, the most common cause of brush sparking is?

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In a universal motor, the most common cause of brush sparking is?

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asked Mar 20, 2018 by anonymous

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The speed of a universal motor is usually reduced by using?

Last Answer : The speed of a universal motor is usually reduced by using gearing.

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asked Mar 20, 2018 by anonymous

Speed control of a universal motor is achieved by?

Last Answer : Speed control of a universal motor is achieved by varying field flux with tapped field windings, connecting rheostat in series, applying variable voltage by means of silicon controlled rectifier, applying variable voltage by means of variable auto-transformer.

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asked Mar 20, 2018 by anonymous

A universal motor is one which?

Last Answer : A universal motor is one which can be operated either on D.C. or A.C. supply at approximately the same speed and output.

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The speed/load characteristics of a universal motor is same as that of?

Last Answer : The speed/load characteristics of a universal motor is same as that of D.C. series motor.

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The speed control of universal motor used for sewing machines is by?

Last Answer : The speed control of universal motor used for sewing machines is by varying the resistance.

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asked Mar 20, 2018 by anonymous

The direction of rotation of universal motor can be reversed the by reversing the flow of current through?

Last Answer : The direction of rotation of universal motor can be reversed the by reversing the flow of current through either armature winding or field winding.

248 views 1 answer

asked Mar 20, 2018 by anonymous

State working principle of universal motor with the help of diagram.

State working principle of universal motor with the help of diagram.
Last Answer : Working Principle of Universal motor : It is modified DC series motor which can work on AC as well as DC supply. According to basic motor principle, whenever a current carrying conductor is placed in magnetic ... They have nearly same operating characteristic for both AC and DC supply.

145 views 1 answer

asked Aug 17, 2019 by anonymous

applications of each: i) Universal motor ii) Stepper motor.

applications of each: i) Universal motor ii) Stepper motor.
Last Answer : i) Applications of Universal motor: 1) portable drills 2) hair dryers 3) grinders 4) mixers 5) table-fans 6) blowers 7) polishers 8) Kitchen appliances ii) Applications of Stepper motor ... 7) robotics 8) CNC machine 9) Control systems 10) Biomedical applications 10) XY recorder 11) plotters

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asked Aug 17, 2019 by anonymous

State two applications of 1) Shaded pole motor 2) Universal motor

State two applications of 1) Shaded pole motor 2) Universal motor
Last Answer : (i)Applications of Shaded pole motor: 1. Small fans 2. Toy motors 3. Hair dryers 4. Ventilators 5. Electric clocks 6. Record players 7. Motorized valves 8. Gramophones 9. Photocopying ... 5. Portable Drilling Machines 6. Electric Shavers 7. Mechanical computing Machines 8. Machine Tools etc.

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asked Jul 26, 2019 by anonymous

Draw and explain working of universal motor. Give two applications of universal motor.

Draw and explain working of universal motor. Give two applications of universal motor.
Last Answer : Figure of Universal motor: Operation of universal motor on A.C. and D.C. supply: *A universal motor works on either DC or single phase AC supply. When the universal motor is ... , regardless of AC or DC supply, universal motor works on the same principle that DC series motor works.

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asked Jul 20, 2019 by anonymous

The speed of a universal motor is generally reduced by using?

Last Answer : The speed of a universal motor is generally reduced by using gear trains.

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asked Mar 20, 2018 by anonymous

A universal motor can run on?

Last Answer : A universal motor can run on either A.C. or D.C.

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asked Mar 20, 2018 by anonymous

Sparking, is discouraged in a D.C. motor because?

Last Answer : Sparking, is discouraged in a D.C. motor because commutator gets damaged.

159 views 1 answer

asked Mar 20, 2018 by anonymous

Sparking at the commutator of a D.C. motor may result in?

Last Answer : Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.

228 views 1 answer

asked Mar 20, 2018 by anonymous

The function of a brush and commutator arrangement in a dc motor is to

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
Last Answer : The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque

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asked Apr 29, 2018 by anonymous

What human gestures are universal?

What human gestures are universal?
Last Answer : The bird. That speaks in every language. Thumbs up also seems pretty universal.

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What is a Universal Blood Donor and a Universal Blood Recipient?

What is a Universal Blood Donor and a Universal Blood Recipient?
Last Answer : A universal blood donor is a person who is eligible to donate blood to any person in the world, except for a few set of people. The universal blood donor must have O- (O negative) blood group in ... type, even O-. So, the donor as well as recipient must be careful while involving in this process.

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asked Jun 24, 2021 by itszee

A universal RLC bridge uses?

A universal RLC bridge uses?
Last Answer : A universal RLC bridge uses Maxwell Wein bridge for measurement of inductance and modified De Santy's bridge for measurement of capacitance.

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asked Mar 21, 2018 by anonymous

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes
Last Answer : Answer: D

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asked Jan 4 by itszee

In a 4-pole wave winding connected dc motor, the cross-magnetizing AT/pole for a brush shift of θ radians

In a 4-pole wave winding connected dc motor, the cross-magnetizing AT/pole for a brush shift of θ radians (A) Armature amp-conductors × (θ/360o) (B) Armature amp-turns × (θ/360o) (C) Armature amp-conductors × (1/4 - θ/360o) (D) Armature amp-conductors × (1/8 - θ/360o)
Last Answer : In a 4-pole wave winding connected dc motor, the cross-magnetizing AT/pole for a brush shift of θ radians Armature amp-conductors × (1/8 - θ/360o)

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asked Apr 28, 2018 by anonymous

Split phase induction motor

Split phase induction motor
Last Answer : Split phase induction motor : There are two windings used in split phase induction motor. It is a type of single-phase induction motor. There are two winding one is called main winding and ... motor have low starting torque it is used for small fans, blowers, centrifugal pumps, grinders etc.

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asked Sep 20, 2018 by anonymous

Describe the reason of using dc series motor for electric trains.

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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asked Sep 18, 2018 by anonymous

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s.

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be
Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

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asked May 8, 2018 by anonymous

Damper winding in a synchronous motor

Damper winding in a synchronous motor
Last Answer : Damper winding in a synchronous motor Serves to start the motor.

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asked May 8, 2018 by anonymous

In a double squirrel cage induction motor, good starting torque is produced as

In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high ... the outer high resistance winding. (D) Large current flows through the inner low resistance winding.
Last Answer : In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.

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asked May 8, 2018 by anonymous

A change of 4% in the supply voltage to an induction motor will produce a change of approximately

A change of 4% in the supply voltage to an induction motor will produce a change of approximately
Last Answer : A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque

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asked May 8, 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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asked May 3, 2018 by anonymous

In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will

In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times
Last Answer : In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth

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asked May 1, 2018 by anonymous

The speed of a three-phase induction motor is controlled by variable voltage variable frequency control

The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque (1) Decreases (2) Increases (3) Remains constant (4) None of the above
Last Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases

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asked May 1, 2018 by anonymous

The number of poles of 8/6 stepper motor can be :

The number of poles of 8/6 stepper motor can be :
Last Answer : The number of poles of 8/6 stepper motor can be : 4

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asked Apr 30, 2018 by anonymous

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

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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asked Apr 29, 2018 by anonymous

For using regenerative breaking, the most suitable motor is :

For using regenerative breaking, the most suitable motor is : (A) DC series motor (B) Slip ring induction motor (C) Squirrel cage induction motor (D) Synchronous motor
Last Answer : For using regenerative breaking, the most suitable motor is : Slip ring induction motor

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asked Apr 29, 2018 by anonymous

Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to

Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be
Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m

422 views 1 answer

asked Apr 29, 2018 by anonymous

The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is

The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is
Last Answer : The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is 4 percent

361 views 1 answer

asked Apr 29, 2018 by anonymous

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for
Last Answer : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles

304 views 1 answer

asked Apr 29, 2018 by anonymous

The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min

The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min (A) 100 rpm (B) 200 rpm (C) 400 rpm (D) 800 rpm
Last Answer : The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min 200 rpm

151 views 1 answer

asked Apr 28, 2018 by anonymous

In a split-phase induction motor, the resistance/reactance ratios of windings are such that

In a split-phase induction motor, the resistance/reactance ratios of windings are such that (A) current in the auxiliary winding leads the current in the main winding (B) current in the ... (C) both windings develop the same starting torque (D) both windings develop high starting current
Last Answer : In a split-phase induction motor, the resistance/reactance ratios of windings are such that current in the auxiliary winding leads the current in the main winding

106 views 1 answer

asked Apr 28, 2018 by anonymous

In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then

In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in ... increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor
Last Answer : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then the flux first decreases and then increases in the same direction

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asked Apr 28, 2018 by anonymous

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu
Last Answer : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu

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asked Apr 28, 2018 by anonymous

The effect of increasing load on a synchronous motor running with normal excitation is

The effect of increasing load on a synchronous motor running with normal excitation is (A) Increase both its Ia and power factor. (B) Decrease Ia, but increase power factor. (C) Increase Ia, but decrease power factor (D) Decrease both Ia and power factor.
Last Answer : The effect of increasing load on a synchronous motor running with normal excitation is Increase Ia, but decrease power factor

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asked Apr 28, 2018 by anonymous

A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor

A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60
Last Answer : 0

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asked Apr 28, 2018 by anonymous

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW.

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is (A) 5.06 kW (B) 0.3 kW (C) 100 kW (D) 83.33 kW
Last Answer : An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is 83.33 kW

179 views 1 answer

asked Apr 28, 2018 by anonymous

The torque developed by any 3-phase induction motor at 0.8 p.u. slip is

The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Last Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque

3.1k views 1 answer

asked Apr 28, 2018 by anonymous

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω
Last Answer : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω

165 views 1 answer

asked Apr 28, 2018 by anonymous

A three-phase synchronous motor connected to ac mains is running at full load and unity power factor.

A three-phase synchronous motor connected to ac mains is running at full load and unity power factor. lf its shaft load is reduced by half and field current is held constant then its new power factor will be
Last Answer : Leading

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asked Apr 28, 2018 by anonymous

In variable speed motor?

Last Answer : In variable speed motor a weaker commutating field is needed at low speed than at high speed.

62 views 1 answer

asked Mar 20, 2018 by anonymous

If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor?

Last Answer : If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.

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asked Mar 20, 2018 by anonymous

Which motor has the poorest speed control?

Last Answer : Series motor has the poorest speed control.

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asked Mar 20, 2018 by anonymous

For a D.C. shunt motor if the excitation is changed?

Last Answer : For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.

168 views 1 answer

asked Mar 20, 2018 by anonymous

The speed of a D.C. motor can be controlled by varying

The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above
Last Answer : The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

389 views 1 answer

asked Mar 20, 2018 by anonymous

anonymous · Answer 1 · 2018-03-20T19:40:10+0000

In a universal motor, the most common cause of brush sparking is open armature winding, shorted armature winding, shorted field winding, high commutator mica.

In a universal motor, the most common cause of brush sparking is?

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