94 views

1 Answer

Answer :

Most of the fractional horsepower motors have either plain or sleeve bearings.

Like 0 like

Please log in or register to answer this question.

Related questions

358 views

Last Answer : In D.C. machines fractional pitch winding is used to reduce the sparking.

1 answer
200 views

Description : Why engine power is measured in horsepower (HP) ?

Last Answer : James Watt compared engine output with that of work done by a horse. WD by horse = 746W.

2 answers
87 views

Last Answer : The horsepower of steam locomotives is up to 1500.

1 answer
82 views

Last Answer : For diesel locomotives the range of horsepower is 1500 to 2500.

1 answer
102 views

Last Answer : The value of starting capacitor of a fractional horse power motor will be 300 uF .

1 answer
101 views

Description : Damper winding is provided in 3 phase synchronous motors to :

Last Answer : Damper winding is provided in 3 phase synchronous motors to : provide starting torque and prevent hunting

1 answer
71 views

Description : Stepper motors are used in  (1) printers (2) lifts (3) amplifiers (4) oscillators

Last Answer : Stepper motors are used in printers 

1 answer
82 views

Description : Slot harmonics are reduced in induction motors by using (A) fractional-pitch windings (B) fractional-slot windings (C) integral-slot windings (D) distributed windings

Last Answer : Slot harmonics are reduced in induction motors by using fractional-slot windings

1 answer
104 views

Description : Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as (A) One-third of their synchronous speed (B) One-fifth of their synchronous speed (C) One-seventh of their synchronous speed (D) One-ninth of their synchronous speed

Last Answer : Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as One-seventh of their synchronous speed

1 answer
251 views

Description : Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.

Last Answer : Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.

1 answer
213 views

Description : Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these

Last Answer : Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these

1 answer
98 views

Description : In case of conductively compensated D.C. series motors, the compensating winding is provided?

Last Answer : In case of conductively compensated D.C. series motors, the compensating winding is provided in series with armature winding.

1 answer
252 views

Last Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.

1 answer
87 views

Last Answer : A direct online starter is used for starting motors up to 5 H.P.

1 answer
387 views

Last Answer : When two D.C. series motors are connected in parallel, the resultant speed is normal speed.

1 answer
155 views

Last Answer : In D.C. shunt motors as load is reduced the speed will remain almost constant.

1 answer
124 views

Last Answer : Starters are used with D.C. motors because to restrict armature current as there is no back e.m.f. while starting.

1 answer
127 views

Last Answer : Differentially compound D.C. motors can find applications requiring low starting torque.

1 answer
135 views

Last Answer : The capacitors used in single-phase capacitor motors have no polarity marking.

1 answer
118 views

Last Answer : As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for sound equipment.

1 answer
79 views

Description : What are the five types of single phase motors used in the industry?

0 answers
145 views

Description : What is the difference between synchronous and asynchronous motors?

Last Answer : The motor which rotates at constant speed is called synchronous motor. And that constant speed is called as synchronous speed.  And the motor which does not rotates at constant speed are called asynchronous motor. Asynchronous motor is also called as Induction motor.

1 answer
21 views

Description : SYNCHRONOUS MOTORS MCQ

Last Answer : 101. In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then (a) the motor is said to be fully loaded (b) the torque ... square of the applied voltage (c) inversely proportional to applied voltage (d) none of the above Ans: a

3 answers
25 views

Description : SINGLE PHASE INDUCTION MOTORS MCQ

Last Answer : 101. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on (a) running winding (b) rotor winding (c) field winding (d) compensating winding Ans: a ... motor is usually reduced by using (a) gearing (b) belts (c) brakes (d) chains Ans: a

3 answers
347 views

Description : THREE PHASE INDUCTION MOTORS MCQ

Last Answer : 101. Insertion of resistance in the stator of an induction motor (a) increases the load torque (b) decreases the starting torque (c) increases the starting torque (d) none of the above Ans: b

3 answers
164 views

Description : Why are DC motors used in trains and not AC motors ?

Last Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.

1 answer
78 views

Description : Suggest electric motors for i) traction ii) crane iii) lathe machine iv) domestic fan.

Last Answer : i) Traction :- DC Series motor  ii) Crane :- DC Series motor  iii) Lathe machine :- 3 phase Induction motor or DC shunt motor  iv) Domestic fan :- 1 phase induction motor

1 answer
95 views

Description : State which electric motors are generally used in electro agro systems with reason.

Last Answer : 1) 3 phase induction motor is used in electro agro system for water pumping from wells as 3 phase ac supply is easily available, cost of induction motor is less, maintenance free being rugged ... as 1 phase ac supply is easily available for domestic purpose, repair is simple and easily available.

1 answer
1.9k views

Description : State factors for selection of motors as drive.

Last Answer : Following Factors governing / or are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- ... level, load equalization 7) Cost: - Capital, Running and maintenance cost should be less.

2 answers
2.5k views

Description : Compare variable reluctance and permanent magnet motors.

Last Answer : Variable reluctance Motor  Permanent magnet motors   The rotor is not magnetised The rotor is magnetised  High torque to inertia ratio  Low torque to inertia ratio  ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction. 

1 answer
148 views

Description : What are the factors to be considered while selection of motors for different drives?

Last Answer : Following Factors are considered while selecting electric drive (Motor) for particular application:  Factors to be considered for selection of Electrical Drives:  1) Nature of Supply:- Whether supply ... , load equalization 7) Cost: - Capital, Running and maintenance cost should be less.  

1 answer
2.6k views

Description : 3 phase motor  42 hp  same ratting two motors  but pole change 2 and 4 pole   tell me difference amp of both motors

0 answers
554 views

Description : A relay used for protection of motors against overload is :  (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay

Last Answer : D

2 answers
193 views

Description : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above

Last Answer : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above

1 answer
89 views

Last Answer : During rheostat braking of D.C. series motors motor is run as a generator.

1 answer
91 views

Last Answer : D.C. shunt motors are used for driving machine tools.

1 answer
163 views

Last Answer : The D.C. motors preferred for traction applications beacuse the speed is inversely proportional to the torque and the torque is proportional to square of armature current.

1 answer
121 views

Last Answer : The range of efficiency for shaded pole motors is 5% to 35%.

1 answer
725 views

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.

1 answer
105 views

Last Answer : In capacitor start single-phase motors current in the starting winding leads the voltage.

1 answer
101 views

Last Answer : The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.

1 answer
95 views

Last Answer : Synchronous motors are generally not self-starting because the direction of instantaneous torque reverses after half cycle.

1 answer
112 views

Last Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.

1 answer
181 views

Description : The efficiencies of transformers compared with that of electric motors of the same power are?

Last Answer : Transformers have high efficiency than the same ratted motors

2 answers
71 views

Description : Do AC induction motors have back EMF?

0 answers
3 views

Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.

Last Answer : Answer: B

1 answer
101 views

Description : The power factor of a squirrel cage induction motor is (A) low at light load only. (B) low at heavy load only.

0 answers
39 views

Description : A 50 Hz, 3-phase induction motor delivers a full load speed of 1440 r.p.m. The number of poles of the motor will be

0 answers
2 views

Description : Which type of motor would you recommend for using in a steel mill and on an electric vehicle? Explain your answer

0 answers
2 views

Description : How do I compare the horsepower ratings of inboard vs. outboard motors - is one kind more powerful?

Last Answer : Inboard engines are quieter and are normally more powerful than outboard motors. Outboards are normally less exspensive and easier to maintain.

1 answer
...