**Description :** What is pony motor starting?

**Last Answer :** In this method the rotor is made to rotate by some external device called pony motors. Once the rotor attains synchronous speed, the DC excitation to the rotor is switched on. Once synchronism is established the pony motor is decoupled. The synchronous motor continuously runs at synchronous speed.

**Description :** A pony motor is basically a?

**Last Answer :** Pony motor is basically a small induction motor.

**Description :** The heating time constant of a totally enclosed motor is relatively Select one: a. higher b. lower c. independent of type of enclosure. d. small .

**Last Answer :** B

**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.

**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

**Description :** Which motor is generally used in Tap Recorders? A) universal motor B) reluctance motor C) split phase motor D) hysteresis motor

**Last Answer :** Which motor is generally used in Tap Recorders? A) universal motor B) reluctance motor C) split phase motor D) hysteresis motor

**Description :** As compared to a split phase motor, a capacitor start motor has _____.

**Last Answer :** As compared to a split phase motor, a capacitor start motor has higher starting torque.

**Description :** For very low speed and high power applications the best suited ac motor is:

**Last Answer :** For very low speed and high power applications the best suited ac motor is: synchronous motor

**Description :** If the current in the armature of do series motor is reduced to 5%, the torque of the motor will become: (1) 50% of the previous value (2) 25% of the previous value (3) 150% of the previous value (4) 125% of the previous value

**Last Answer :** If the current in the armature of do series motor is reduced to 5%, the torque of the motor will become: 25% of the previous value

**Description :** For a 1.8o, 2-phase bipolar stepper motor, the stepping rate is 100 steps/second. The rotational speed of the motor in rpm is (A) 15 (B) 30 (C) 60 (D) 90

**Last Answer :** For a 1.8o, 2-phase bipolar stepper motor, the stepping rate is 100 steps/second. The rotational speed of the motor in rpm is 30

**Description :** The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 ... .5 A from the same source will be (A) 48.0% (B) 57.1% (C) 59.2% (D) 88.8%

**Last Answer :** The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 48.0%

**Description :** The following motor definitely has a permanent magnet rotor (A) DC commutator motor (B) Brushless dc motor (C) Stepper motor (D) Reluctance motor

**Last Answer :** The following motor definitely has a permanent magnet rotor Stepper motor

**Description :** A 400 V, 50 Hz 30 hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging. The stator and rotor copper losses are 1.5 kW and 900 W respectively. The friction and windage losses are 1050 W and the ... the motor will be (A) 23.06 kW (B) 24.11 kW (C) 25.01 kW (D) 26.21 kW

**Last Answer :** A 400 V, 50 Hz 30 hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging. The stator and rotor copper losses are 1.5 kW and 900 W respectively. The friction and windage losses are 1050 W and the core losses are 1200 W. The air-gap power of the motor will be 25.01 kW

**Description :** In a stepper motor, the detent torque means (A) minimum of the static torque with the phase winding excited (B) maximum of the static torque with the phase winding excited (C) minimum of ... torque with the phase winding unexcited (D) maximum of the static torque with the phase winding unexcited

**Last Answer :** In a stepper motor, the detent torque means maximum of the static torque with the phase winding unexcited

**Description :** The locked rotor current in a 3-phase, star connected 15 , kW 4 , pole 230 V , 50 Hz induction motor at rated conditions is 50 A. Neglecting losses and magnetizing current, the approximate locked rotor line current drawn when the motor ... Hz supply is (A) 58.5 A (B) 45.0 A (C) 42.7 A (D) 55.6 A

**Last Answer :** The locked rotor current in a 3-phase, star connected 15 , kW 4 , pole 230 V , 50 Hz induction motor at rated conditions is 50 A. Neglecting losses and magnetizing current, the approximate locked rotor line current drawn when the motor is connected to a 236 , V 57 Hz supply is 45.0 A

**Description :** 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°

**Description :** Which type of motor is most suitable for computerprinter drive? A) Reluctance motor B) Hysteresis motor C) Shaded pole motor D) Stepper motor

**Last Answer :** Stepper motor type of motor is most suitable for computer printer drive?.

**Description :** The torque speed characteristic of a repulsion motor resembles which of the following d.c. motor characteristics A) Separately excited B) Shunt C) Series D) Compound

**Last Answer :** The torque speed characteristic of a repulsion motor resembles which of the following d.c. motor characteristics Series

**Description :** In a Synchronous motor, the magnitude of stator back e.m.f (Eb) depends on

**Last Answer :** In a Synchronous motor, the magnitude of stator back e.m.f (Eb) depends on DC excitation only

**Description :** When running under no-load condition and with over excitation, armature current Ia drawn by a synchronous motor

**Last Answer :** When running under no-load condition and with over excitation, armature current Ia drawn by a synchronous motor Leads the applied voltage

**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

**Description :** Damper winding in a synchronous motor

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

**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.

**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

**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

**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

**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

**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

**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

**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

**Description :** Slip test is performed to determine : (A) Slip in an induction motor (B) Xd and Xq in a salient pole alternator (C) Synchronous impedance in an alternator (D) Positive and negative sequence impedances of an alternator

**Last Answer :** Slip test is performed to determine : Xd and Xq in a salient pole alternator

**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

**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

**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

**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

**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

**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

**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

**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

**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

**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

**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

**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

**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

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

**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.

**Last Answer :** Series motor has the poorest speed control.

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

**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