A centre zero ammeters connected in the rotor circuit of a 6-pole 50 Hz induction motor makes 30...

A centre zero ammeters connected in the rotor circuit of a 6-pole 50 Hz induction motor makes 30 oscillations in one minute. The rotor speed is
by

1 Answer

Answer :

A centre zero ammeters connected in the rotor circuit of a 6-pole 50 Hz induction motor makes 30 oscillations in one minute. The rotor speed is 990.

by

Related questions

The locked rotor current in a 3-phase, star connected 15 , kW 4 , pole 230 V , 50 Hz induction motor at rated

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 

The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about (A) 50 Hz. (B) 20 Hz. (C) 2 Hz. (D) Zero.

Description : The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about (A) 50 Hz. (B) 20 Hz. (C) 2 Hz. (D) Zero.

Last Answer : (C) 2 Hz.

The power input to the rotor of a 400V, 50 Hz 6 pole three phase induction motor is 20kW. The slip is 3%...

Description : The power input to the rotor of a 400V, 50 Hz 6 pole three phase induction motor is 20kW. The slip is 3%. The frequency of rotor currents is: (A) 1 Hz (B) 1.5 Hz (C) 2 Hz (D) 1 2 Hz

Last Answer : C

A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Description : A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Last Answer : Ans: B N = NS (1-S) and NS =120 f / p =120 x 50 /4 = 1500 rpm ∴N= 1500 (1-0.02) =1470 rpm

A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m.

Description : A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m.

Last Answer : (D) 75 r.p.m.

A 400 V, 15 kW, 4-pole, 50 Hz, Y-connected induction motor has full load slip of 4%. The output torque of the

Description : A 400 V, 15 kW, 4-pole, 50 Hz, Y-connected induction motor has full load slip of 4%. The output torque of the machine at full load is  (A) 1.66 Nm (B) 95.50 Nm (C) 99.47 Nm (D) 624.73 Nm

Last Answer : A 400 V, 15 kW, 4-pole, 50 Hz, Y-connected induction motor has full load slip of 4%. The output torque of the machine at full load is 99.47 Nm

A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Description : A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Last Answer : Answer: A

An 8 pole wound rotor induction motor operating on 60 Hz supply is driven at 1800 r.p.m. by a prime mover in

Description : An 8 pole wound rotor induction motor operating on 60 Hz supply is driven at 1800 r.p.m. by a prime mover in the opposite direction of revolving magnetic field. The frequency of the rotor current is (a) 30 Hz (b) 60 Hz (c) 120 Hz (d) 180 Hz 

Last Answer : 30 Hz As the frequency of the rotor is given by  F= N*P/120 so from the above equation the frequency of the rotor current can be easily calculated  i.e. 1800×8/120=30 Hence the required value of rotor frequency is 30 Hz

A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is ...

Description : A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is: (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m

Last Answer : A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is: 75 r.p.m

The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Description : The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Last Answer : Ns         equals        f/pair pole 50/4      - 12.5

What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is

Description : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these

Last Answer : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these

The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open

Description : The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the ... frequency of induced voltage across slip ring is A) 30 Hz B) 70 Hz C) 20 Hz D) 35 Hz

Last Answer : The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the normal direction, The frequency of induced voltage across slip ring is 70 Hz

A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440

Description : A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440 rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is  (A) 100 (B) 98 (C) 52 (D) 48

Last Answer : A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440 rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is 98 

A 3 phase, 400 volts, 50 Hz, 100 kW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a...

Description : A 3 phase, 400 volts, 50 Hz, 100 kW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of: (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Last Answer : 1470rpm

The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Description : The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Last Answer : (D) 1710 rpm

The rotor frequency for a 3 phase 1000 RPM 6 pole induction motor with a slip of 0.04 is________Hz (A) 8 (B) 4 (C) 6 (D) 2

Description : The rotor frequency for a 3 phase 1000 RPM 6 pole induction motor with a slip of 0.04 is________Hz (A) 8 (B) 4 (C) 6 (D) 2

Last Answer : Ans: D Given: N=1000 rpm ; P= 6; s= 0.04; and f = NP/ 120 = 10006/120 = 50 Hz Rotor frequency fr=sf = 0.0450 = 2.0 Hz

The rotor frequency for a 3-phase 6-pole, 1000 r.p.m. induction motor with a slip of 0.04 is

Description : The rotor frequency for a 3-phase 6-pole, 1000 r.p.m. induction motor with a slip of 0.04 is (a) 2 Hz (b) 4 Hz (c) 6 Hz (d) 8 Hz  

Last Answer : 2hz is rotor frequency

A 6-pole, 50Hz, 3-φ induction motor is running at 950 r.p.m. and has Cu loss of 5kW. The rotor input is

Description : A 6-pole, 50Hz, 3-φ induction motor is running at 950 r.p.m. and has Cu loss of 5kW. The rotor input is (a) 10 kW (b) 95 kW (c) 100 kW (d) 9.5 kW 

Last Answer : s=(Ns-N)/Ns =(1000-950)/1000=0.05.rotor cu.loss= s*rotor inputwe have rotor cu loss=5kWtherefore, rotor input= rotor cu.loss/s                              =5kW/0.05                              =100 kW

The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit

Description : The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit

Last Answer : Answer: A

If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Description : If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Last Answer : Answer: C

Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Description : Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Last Answer : Ans: C Given : s = 0.02 ; f = 50 Hz Therefore, frequency of rotor induced emf = s f = 0.02 x 50 = 1.0 Hz

What is the rotor speed of a four pole, 60 cycle, induction motor operating at full load with 3% slip? A. 270 RPM B. 540 RPM C. 873 RPM D. 1746 RPM

Description : What is the rotor speed of a four pole, 60 cycle, induction motor operating at full load with 3% slip? A. 270 RPM B. 540 RPM C. 873 RPM D. 1746 RPM

Last Answer : Answer: D

In the illustrated device, the part labeled '1A' _________. EL-0001 A. are start and run windings for a single phase shaded pole induction motor B. is the stator for a polyphase induction motor C. is the armature for a squirrel cage rotor motor D. are direct current shunt field windings for a universal motor

Description : In the illustrated device, the part labeled '1A' _________. EL-0001 A. are start and run windings for a single phase shaded pole induction motor B. is the stator for a polyphase induction ... armature for a squirrel cage rotor motor D. are direct current shunt field windings for a universal motor

Last Answer : Answer: B

A single-phase induction motor having a relatively high starting torque, is the ___________. A. shaded pole motor B. wound-rotor motor C. capacitor-start motor D. resistance-start motor

Description : A single-phase induction motor having a relatively high starting torque, is the ___________. A. shaded pole motor B. wound-rotor motor C. capacitor-start motor D. resistance-start motor

Last Answer : Answer: C

Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Description : Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Last Answer : 1) Pole Changing Method:  Synchronous speed is given by, From the above equation of synchronous speed, it can be seen that synchronous speed (and hence, running speed) can ... in voltage and consequently the speed decreases and vice versa. Ultimately speed depends on the supply voltage.

If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor

Description : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is:

Last Answer : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is: zero

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

A 6 pole 3-phase wound-rotor induction machine is driven by another machine at 1800 rpm. The rotor of the ...

Description : A 6 pole 3-phase wound-rotor induction machine is driven by another machine at 1800 rpm. The rotor of the induction machine is connected to a 50Hz system. If the mechanical rotation of the rotor is in the same direction as the rotor winding flux rotation, then frequency of the stator voltage will be

Last Answer : A 6 pole 3-phase wound-rotor induction machine is driven by another machine at 1800 rpm. The rotor of the induction machine is connected to a 50Hz system. If the mechanical rotation of ... the same direction as the rotor winding flux rotation, then frequency of the stator voltage will be 140 Hz.

A 400 V, 50 Hz 30 hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging.

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

A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading....

Description : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be

Last Answer : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be 1165 Nm

A separately excited d.c. machine is coupled to a 50 Hz, three-phase, 4-pole induction machine as shown in

Description : A separately excited d.c. machine is coupled to a 50 Hz, three-phase, 4-pole induction machine as shown in the figure. The Dc machine is energized first and the machines rotate at 1 600 ... three phase source, the phase sequence being consistent with the direction of rotation. In steady state

Last Answer : A separately excited d.c. machine is coupled to a 50 Hz, three-phase, 4-pole induction machine as shown in the figure. The Dc machine is energized first and the machines rotate at 1 600 1pm. ... rotation. In steady state DC machine acts as a motor and the induction machine acts as a generator  

The synchronous speed for the seventh space harmonic mmf wave of a 3-phase, 8-pole, 50 Hz induction

Description : The synchronous speed for the seventh space harmonic mmf wave of a 3-phase, 8-pole, 50 Hz induction machine is  (A) 107.14 rpm in forward direction (B) 107.14 rpm in reverse direction (C) 5250 rpm in forward direction (D) 5250 rpm in reverse direction

Last Answer : The synchronous speed for the seventh space harmonic mmf wave of a 3-phase, 8-pole, 50 Hz induction machine is 107.14 rpm in forward direction 

A 50 Hz, 3—phase induction motor has a full load speed of 1440 rpm. The number of poles of the motor is: ...

Description : A 50 Hz, 3—phase induction motor has a full load speed of 1440 rpm. The number of poles of the motor is:   (A)4 (8)6 (0)12  (D)8

Last Answer : Ans: A N= Ns (1-S) = NS –NS x S 1440 = Ns (1-S) Ns = 1440 / (1-S) Ns = (120 f/ p) = 120 x 50/p = 6000 p Ns will be closer to N i.e 1440 When P=2 ; Ns = 3000 rpm , not close to N When P=4 ; Ns = 1500 rpm , it is closer to N Therefore P =4 for N=1440

A 1.8°step, 4-phase stepper motor has a total of 40 teeth on 8 pole of stator. The number of rotor teeth for their rotor will be (A) 40 (B) 50 (C) 100 (D) 80

Description : A 1.8°step, 4-phase stepper motor has a total of 40 teeth on 8 pole of stator. The number of rotor teeth for their rotor will be (A) 40 (B) 50 (C) 100 (D) 80

Last Answer : (B) 50

Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage

Description : Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage

Last Answer : Answer: C

A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit

Description : A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit

Last Answer : Answer: D

The variable resistance placed in the rotor circuit of a wound-rotor induction motor provides for __________. A. speed control B. frequency control C. voltage control D. use as a split-phase motor

Description : The variable resistance placed in the rotor circuit of a wound-rotor induction motor provides for __________. A. speed control B. frequency control C. voltage control D. use as a split-phase motor

Last Answer : Answer: A

A motor using a rheostat in the motor circuit to vary the speed is called a ____________. A. squirrel-cage induction motor B. regenerative braking motor C. wound-rotor induction motor D. synchronous motor

Description : A motor using a rheostat in the motor circuit to vary the speed is called a ____________. A. squirrel-cage induction motor B. regenerative braking motor C. wound-rotor induction motor D. synchronous motor

Last Answer : Answer: C

Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. The starting current is held below the rated current. D. The field winding is energized for starting purposes only.

Description : Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. ... is held below the rated current. D. The field winding is energized for starting purposes only.

Last Answer : Answer: A

A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Description : A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Last Answer : The number of poles in an induction motor can be calculated using the following formula: No. of poles = (120 * frequency) / speed In this case, the number of poles would be calculated as follows: No. of poles = ( ... ) - 50 Hz = 8.08 Hz So the motor has 6 poles and a slip frequency of 8.08 Hz.

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 number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?

Description : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?

Last Answer : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4.

A 3-phase induction motor under locked rotor condition and with stator supply, induces

Description : A 3-phase induction motor under locked rotor condition and with stator supply, induces (A) small voltage at slip frequency (B) large voltage at rotor frequency (C) zero voltage at zero frequency (D) large voltage at slip frequency

Last Answer : A 3-phase induction motor under locked rotor condition and with stator supply, induces (A) small voltage at slip frequency (B) large voltage at rotor frequency (C) zero voltage at zero frequency (D) large voltage at slip frequency

In an induction motor, if the rotor resistance is equal to stand-still reactance then the maximum torque is_________.

Last Answer : In an induction motor, if the rotor resistance is equal to stand-still reactance then the maximum torque is equal to starting torque.

The purpose of skewing of rotor slots in induction motor is_________.

Last Answer : The purpose of skewing of rotor slots in induction motor is to reduce the locking tendency of rotor.

When the frequency of the rotor of an induction motor is small, it can be measured by_________.

Last Answer : When the frequency of the rotor of an induction motor is small, it can be measured by d.c. moving coil milli-voltmeter

A 200 V, 50 Hz inductive circuit takes a current of 10 A at 30 degree lagging pf, what is the inductive ...

Description : A 200 V, 50 Hz inductive circuit takes a current of 10 A at 30 degree lagging pf, what is the inductive reactance of the circuit?  (A) 17.8 Ω (B) 100 Ω (C) 178 Ω (D) 10 Ω 

Last Answer : D

The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted

Description : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be

Last Answer : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be 0.5 Ohm

lf slip of an induction machine is 0.02 and the stator supply frequency is 50 Hz, what will be the frequency...

Description : lf slip of an induction machine is 0.02 and the stator supply frequency is 50 Hz, what will be the frequency of the rotor induced e.m.f.? (A) 10 Hz (B) 50 Hz (C) 1 Hz (D) 2500 Hz

Last Answer : 1hz