# Differentially compound D.C. motors can find applications requiring?

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

## Related questions

Answer : For the parallel operation of two or more D.C. compound generators, we should ensure that series fields of all generators should be either on positive side or negative side of the armature.

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

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

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.

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

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

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

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.

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

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

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

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

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

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.

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

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

Description : What is the smallest unit of a compound with the same chemical characteristics?

Answer : The molecule is the smallest unit of a compound with the same chemical characteristics.

Answer : In a differentially compounded D.C. motor, if shunt field suddenly opens the motor will first stop and then run in opposite direction as series motor.

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

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

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

Answer : Stepper motors are used in printers

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

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

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

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

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.

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.

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

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

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

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

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

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

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.

Answer : Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be cumulatively compounded.

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

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

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

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.

Description : State factors for selection of motors as drive.

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.

Description : Compare variable reluctance and permanent magnet motors.

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.

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

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.

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

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

Answer : A relay used for protection of motors against overload is : Thermal relay

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

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.

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

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

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

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

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

Answer : Transformers have high efficiency than the same ratted motors

Description : Do AC induction motors have back EMF?

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

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

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

Answer : By looking at Commutator part of the motor, it can be easily confirmed that a particular motor is D.C. motor.

Answer : The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.

Answer : The direction of rotation of a D.C. series motor can be changed by interchanging field terminals.

Description : Draw the connection diagram of long shunt differential D.C. compound generator.