The no load speed of a d.c. shunt motor is 1140 rpm. At full load, the armature reaction weakens the main...

The no load speed of a d.c. shunt motor is 1140 rpm. At full load, the armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full load speed in rpm will be: (A) 1080 (B) 1203 (C) 1000 (D) 1200
by

1 Answer

Answer :

The no load speed of a d.c. shunt motor is 1140 rpm. At full load, the armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full load speed in rpm will be: 1080

by

Related questions

A d.c. shunt motor runs at no load speed of 1140 r.p.m. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full load speed in r.p.m. is (A) 1080 (B) 1203 (C) 1000 (D) 1200

Description : A d.c. shunt motor runs at no load speed of 1140 r.p.m. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full load speed in r.p.m. is (A) 1080 (B) 1203 (C) 1000 (D) 1200

Last Answer : (A) 1080

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

A 400kW, 3 -phase, 440V, 50Hz induction motor has a speed of 950 rpm on full load. The machine has 6 poles. ...

Description : A 400kW, 3 -phase, 440V, 50Hz induction motor has a speed of 950 rpm on full load. The machine has 6 poles. The value of slip for the machine will be (A) 0.06 (B) 0.10 (C) 0.04 (D) 0.05

Last Answer : A 400kW, 3 -phase, 440V, 50Hz induction motor has a speed of 950 rpm on full load. The machine has 6 poles. The value of slip for the machine will be 0.05

A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of the machine as a motor will be (A) 800 rpm. (B) more than 800 rpm. (C) less than 800 rpm. (D) both higher or lower than 800 rpm.

Description : A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of ... . (B) more than 800 rpm. (C) less than 800 rpm. (D) both higher or lower than 800 rpm.

Last Answer : (C) less than 800 rpm.

An increase in the amount of current flow through the armature of a shunt motor is the final result of a/an _____________. A. increase in the load on the motor B. decrease in the load on the motor C. increase in counter EMF D. decrease in armature torque

Description : An increase in the amount of current flow through the armature of a shunt motor is the final result of a/an _____________. A. increase in the load on the motor B. decrease in the load on the motor C. increase in counter EMF D. decrease in armature torque

Last Answer : Answer: A

An open armature connection in a DC propulsion motor could be caused by ____________. A. low-load operation B. clogged ventilation ducts C. sparking at the brushes D. a grounded shunt field coil

Description : An open armature connection in a DC propulsion motor could be caused by ____________. A. low-load operation B. clogged ventilation ducts C. sparking at the brushes D. a grounded shunt field coil

Last Answer : Answer: B

A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, has a flux of 0.4 mWb and the total number of conductors are 1000. What is the value of emf? (A) 100 Volts. (B) 0.1 Volts. (C) 1 Volts. (D) 10 Volts.

Description : A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, has a flux of 0.4 mWb and the total number of conductors are 1000. What is the value of emf? (A) 100 Volts. (B) 0.1 Volts. (C) 1 Volts. (D) 10 Volts.

Last Answer : Ans: D Given N = 1500 rpm, Φ = 0.4 mWb, Z = 1000, P = 4, & A= 4 Therefore, Eb = NΦPZ / 60 A = 1500 x 0.4 x 4 x 1000 x 10^-3 / 60 x 4 = 60/6 = 10 volts

Armature shunting method of speed control of dc shunt motor is preferred over annature resistance method...

Description : Armature shunting method of speed control of dc shunt motor is preferred over annature resistance method due to:  (1) Better speed regulation (2) Less loss in external resistance (3) Simplicity in control circuit (4) Reduced cost of controller

Last Answer : Armature shunting method of speed control of dc shunt motor is preferred over annature resistance method due to: Better speed regulation.

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 four-pole 60-hertz induction motor has a synchronous speed of 1800 RPM and a slip of 4 percent at full load. What will be its full load speed? A. 1728.0 RPM B. 1730.7 RPM C. 1800.0 RPM D. 1872.0 RPM

Description : A four-pole 60-hertz induction motor has a synchronous speed of 1800 RPM and a slip of 4 percent at full load. What will be its full load speed? A. 1728.0 RPM B. 1730.7 RPM C. 1800.0 RPM D. 1872.0 RPM

Last Answer : Answer: A

A four-pole, 60 cycle, squirrel-cage motor has a full load speed of 1725 RPM. What will be the percent of slip at full load? A. 4.16 B. 4.34 C. 95.66 D. 95.84

Description : A four-pole, 60 cycle, squirrel-cage motor has a full load speed of 1725 RPM. What will be the percent of slip at full load? A. 4.16 B. 4.34 C. 95.66 D. 95.84

Last Answer : Answer: A

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

A cumulative dc compound motor runs at 1500 rpm. on full load. If its series field is short-circuited, its speed

Description : A cumulative dc compound motor runs at 1500 rpm. on full load. If its series field is short-circuited, its speed  (1) becomes zero (2) remains unchanged (3) increases (4) decreases

Last Answer : Increases. As it's cumulative compound motor, both series and shunt field both assist each other. If series field is short circuited, the overall field strength will decrease and atop of that ... speed is inversely proportional to field strength.  So, the speed will increase overall.

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

Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in armature reaction are compensated for by the __________ A. governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay

Description : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay

Last Answer : Answer: B

A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm

Description : A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable? A) Ward Leonard control B) Armature ... ) Field resistance control D) It is not possible to run the motor at more than the rated rpm 

Last Answer : A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable? A) Ward Leonard control B) Armature ... Field resistance control D) It is not possible to run the motor at more than the rated rpm 

The speed of a D.C. shunt motor more than its full-load speed can be obtained by?

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

If a DC motor runs faster than designed, with all other conditions being normal, the possible cause could be a/an ______________. A. shorted shunt field coil B. open armature coil C. reversed commutating pole D. overload

Description : If a DC motor runs faster than designed, with all other conditions being normal, the possible cause could be a/an ______________. A. shorted shunt field coil B. open armature coil C. reversed commutating pole D. overload

Last Answer : Answer: A

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

In a series wound motor, the current passing through the field windings is also passing through the _____________. A. armature B. shunt field C. reactance comparator D. laminations

Description : In a series wound motor, the current passing through the field windings is also passing through the _____________. A. armature B. shunt field C. reactance comparator D. laminations

Last Answer : Answer: A

As compared to shunt and compound DC motors, the series DC motor will have the highest torque because of its comparatively ____________ at the start. (A) Lower armature resistance. (B) Stronger series field. (C) Fewer series turns. (D) Larger armature current.

Description : As compared to shunt and compound DC motors, the series DC motor will have the highest torque because of its comparatively ____________ at the start. (A) Lower armature resistance. (B) Stronger series field. (C) Fewer series turns. (D) Larger armature current.

Last Answer : (D) Larger armature current.

The torque, in a _____________is proportional to the square of the armature current (A) DC shunt motor (B) stepper motor (C) 2-phase servomotor (D) DC series motor

Description : The torque, in a _____________is proportional to the square of the armature current (A) DC shunt motor (B) stepper motor (C) 2-phase servomotor (D) DC series motor

Last Answer : (D) DC series motor

A 220 V shunt motor develops a torque of 54 N-m at armature current of 10 A. The torque produced when...

Description : A 220 V shunt motor develops a torque of 54 N-m at armature current of 10 A. The torque produced when the armature current is 20 A, is?

Last Answer : Armature torque, Ta=PØZIa/2πA So Ta1/Ta2=Ia1/Ia2 Ta2=Ta1*Ia2/Ia1        =54*20/10         =108

The armature torque of the D.C. shunt motor is proportional to?

Last Answer : The armature torque of the D.C. shunt motor is proportional to armature current.

In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be?

Last Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

In a 2280 m race Dinesh beats Aarav by 360 m or 6 seconds. In another race on the same track at the same speeds. Aarav and karthick start at one end while Dinesh starts at the opposite end. How many metres would Aarav have covered ,by the time Dinesh meets karthick given that Dinesh speed is 16 m/sec more than that of karthick a) 1140 m b) 2280 m c) 2460 m d) 1180 m

Description : In a 2280 m race Dinesh beats Aarav by 360 m or 6 seconds. In another race on the same track at the same speeds. Aarav and karthick start at one end while Dinesh starts at the opposite end. How many metres would Aarav ... is 16 m/sec more than that of karthick a) 1140 m b) 2280 m c) 2460 m d) 1180 m

Last Answer : B Aarav 's speed =360/6 =60 m/s Time taken by Aarav to cover 2280 m =2280/60= 38 seconds Dinesh 's speed = 2280/60=38 m/s karthick 's speed = 22m/s Time taken by Dinesh to meet karthick in ... direction: Distance covered by Aarav: =2280/(38+22) =2280/60 =38 seconds =(38*60)m =2280 m

The speed of a d.c. shunt motor at no-load is (A) 5 to 10% (B) 15 to 20% (C) 25 to 30% (D) 35 to 40% higher than its speed at rated load.

Description : The speed of a d.c. shunt motor at no-load is (A) 5 to 10% (B) 15 to 20% (C) 25 to 30% (D) 35 to 40% higher than its speed at rated load.

Last Answer : (A) 5 to 10%

Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? A. A four-pole synchronous motor under normal load. B. A four-pole induction motor under no load. C. A six-pole synchronous motor under normal load. D. A six-pole induction motor under full load.

Description : Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? A. A four-pole synchronous motor under normal load. B. A four-pole induction motor under ... A six-pole synchronous motor under normal load. D. A six-pole induction motor under full load.

Last Answer : Answer: A

A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will a) Both increases b) Both decreases c) Increases and decreases d) Decreases and increases

Description : A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will a) Both increases b) Both decreases c) Increases and decreases d) Decreases and increases

Last Answer : Ans: Both increases

The purpose of resistor bank 'R1-R5' in the winch circuit shown in the illustration is to ______________. EL-0102 A. limit armature current in lower and 'series field' current in hoist to obtain required speeds B. divert shunt field current for speed control in both directions of operation C. limit armature current in hoist and 'series field' current in lower to obtain required speeds D. regulate the strength of the brake solenoid 'B1-B2' in both directions of operation

Description : The purpose of resistor bank 'R1-R5' in the winch circuit shown in the illustration is to ______________. EL-0102 A. limit armature current in lower and 'series field' current in hoist to ... required speeds D. regulate the strength of the brake solenoid 'B1-B2' in both directions of operation

Last Answer : Answer: C

A 50 kW dc shunt is loaded to draw rated armature current at any given speed. When driven

Description : A 50 kW dc shunt is loaded to draw rated armature current at any given speed. When driven  (i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, the respective output powers ... kW in (i) and 75 kW in (ii) (D) 50 kW in (i) and 50 kW in (ii)

Last Answer : A 50 kW dc shunt is loaded to draw rated armature current at any given speed. When driven  (i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, the respective output ... kW in (i) and 75 kW in (ii) (D) 50 kW in (i) and 50 kW in (ii)

The prime mover of an AC two pole main propulsion generator drives the generator at 3600 RPM. If the main propulsion motor has 80 poles, what will be the propeller speed? A. 45 RPM B. 80 RPM C. 90 RPM D. 180 RPM

Description : The prime mover of an AC two pole main propulsion generator drives the generator at 3600 RPM. If the main propulsion motor has 80 poles, what will be the propeller speed? A. 45 RPM B. 80 RPM C. 90 RPM D. 180 RPM

Last Answer : Answer: C

As load is added to a shunt motor, the motor will _________. A. speed up B. continue to operate at the same speed C. slow down slightly D. stop

Description : As load is added to a shunt motor, the motor will _________. A. speed up B. continue to operate at the same speed C. slow down slightly D. stop

Last Answer : Answer: C

Why does the speed of a DC shunt motor decrease as the load increases?

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

With the increase in load on a d.c. shunt motor, speed of the motor

Description : With the increase in load on a d.c. shunt motor, speed of the motor (a) increases proportionately (b) remains constant (c) increase slightly (d) reduces slightly 

Last Answer : With the increase in load on a d.c. shunt motor, speed of the motor reduces slightly.

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

If load on a d.c. shunt motor is increased, its speed is decreased due primarily to?

Description : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to?

Last Answer : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to decrease in back e.m.f.

As the load is increased the speed of D.C. shunt motor will?

Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.

Which of the following statements is correct concerning the motor performance curves and data table shown in the illustration? EL-0006 A. The motor RPM at full load is 1737 RPM. B. The motor draws 12.62 kw from the switchboard when operating at full load. C. If the motor was developing 10 HP its power factor would be 0.92. D. All of the above.

Description : Which of the following statements is correct concerning the motor performance curves and data table shown in the illustration? EL-0006 A. The motor RPM at full load is 1737 RPM. B. The motor draws 12.62 kw ... If the motor was developing 10 HP its power factor would be 0.92. D. All of the above.

Last Answer : Answer: D

An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load

Description :  An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: A) 1000 rpm B) 920 rpm C) 950 rpm D) 970 rpm

Last Answer : An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: 970 rpm

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

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

Reduction in the capacitance of a capacitor-start motor, results in reduced (A) Noise. (B) Speed. (C) Starting torque. (D) Armature reaction.

Description : Reduction in the capacitance of a capacitor-start motor, results in reduced (A) Noise. (B) Speed. (C) Starting torque. (D) Armature reaction.

Last Answer : Ans: C Reduction in the capacitance reduces starting voltage, which results in reduced starting torque.

A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to the inherent speed droop built into the governor C. smoke and overload due to field flashover as residual field flux changes polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed

Description : A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to ... polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed

Last Answer : Answer: D

In DC generators, armature reaction is produced by the:

Description : In DC generators, armature reaction is produced by the: (A) field current (B) armature conductors (C) field pole winding (D) load current in armature

Last Answer : In DC generators, armature reaction is produced by the: load current in armature

A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are a) 0.02, 600 W b) 0.04, 580 W c) 0.04, 1160 W d) 0.04, 1200 W

Description : A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are a) 0.02, 600 W b) 0.04, 580 W c) 0.04, 1160 W d) 0.04, 1200 W

Last Answer : Ans: 0.04, 1160 W

The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from

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%

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

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

The frequency of an alternator at a given RPM is determined by the _____________. A. number of turns of wire in the armature coil B. number of magnetic poles C. strength of the magnets used D. output voltage

Description : The frequency of an alternator at a given RPM is determined by the _____________. A. number of turns of wire in the armature coil B. number of magnetic poles C. strength of the magnets used D. output voltage

Last Answer : Answer: B