A universal motor is one which?

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1 Answer

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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Related questions

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.

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.

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

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

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.

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.

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.

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

Description : 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. 

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

Description : 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

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

Description : 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.

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

Description : 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.  

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.

A universal motor can run on?

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

What human gestures are universal?

Description : What human gestures are universal?

Last Answer : The bird. That speaks in every language. Thumbs up also seems pretty universal.

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

Description : 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.

A universal RLC bridge uses?

Description : 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.

Split phase induction motor

Description : 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.

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

Description : 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

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

Description : 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

Damper winding in a synchronous motor

Description : Damper winding in a synchronous motor

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

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

Description : 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.

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

Description : 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

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

Description : 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

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

Description : 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 

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

Description : 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

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

Description : 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

For using regenerative breaking, the most suitable motor is :

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

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

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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

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

Description : 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

In variable speed motor?

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

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.

Which motor has the poorest speed control?

Last Answer : Series motor has the poorest speed control.

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.

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

Description : 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

At the instant of starting when a D.C. motor is put on supply, it behaves like?

Last Answer : At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.

In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will?

Last Answer : In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will remain unchanged.

The speed of a D.C. shunt motor can be increased by?

Last Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent...

Description : As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit?

Last Answer : As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit a resistance is connected in series with armature.