A 8 pole alternator rotates at 750 r.p.m. Its frequency is

A 8 pole alternator rotates at 750 r.p.m. Its frequency is
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A 8 pole alternator rotates at 750 r.p.m. Its frequency is 50 Hz

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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

A 60 Hz, 2 pole alternator should run at

Description : A 60 Hz, 2 pole alternator should run at • a. 3000 r.p.m. c. 1500 r.p.m. • b. 3600 r.p.m. d. 1800 r.p.m.

Last Answer : A 60 Hz, 2 pole alternator should run at 3600 r.p.m.

Drop in alternator frequency is corrected by:

Description : Drop in alternator frequency is corrected by: (1) Damper winding (2) Increased prime mover output (3) Automatic voltage regulator (4) None of these

Last Answer : Drop in alternator frequency is corrected by: Increased prime mover output

Is the speed of alternator is directly proportional to frequency?

Description : Is the speed of alternator is directly proportional to frequency?

Last Answer : Yes, speed of alternator is directly proportional to frequency.

The piston of a steam engine moves in S.H.M. The crank rotates at 180 r.p.m. and the stroke length is 2 metres. The linear velocity of the piston when it is at a distance of 1 metre from the centre is a.8.88 m/sec b.16.32 m/sec c.5.88 m/sec d.8.16 m/sec e.Zero

Description : The piston of a steam engine moves in S.H.M. The crank rotates at 180 r.p.m. and the stroke length is 2 metres. The linear velocity of the piston when it is at a distance of 1 metre from the centre is a.8.88 m/sec b.16.32 m/sec c.5.88 m/sec d.8.16 m/sec e.Zero

Last Answer : e. Zero

In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be:

Description :  In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50

Last Answer :  In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50

If the excitation of an alternator operating in parallel with other alternators decreased, its:

Description : If the excitation of an alternator operating in parallel with other alternators decreased, its: (1) Power factor becomes more leading (2) Output Kw will change (3) Power factor becomes more lagging (4) Power factor becomes unity

Last Answer : If the excitation of an alternator operating in parallel with other alternators decreased, its: Power factor becomes more leading

State working principle of alternator. State the meaning self and separate excitation.

Description : State working principle of alternator. State the meaning self and separate excitation. 

Last Answer : Working principle of alternator: When a conductor is moved in magnetic field or a magnetic field moved with respect to conductor, according to Faraday's law of electromagnetic induction, the conductor ... like battery or shaft-mounted exciter, then the excitation is said to be separate excitation.

Explain the construction of alternator with neat diagram.

Description : Explain the construction of alternator with neat diagram.

Last Answer : Diagram: Construction of three phase alternator: Construction wise, an alternator generally consists of field poles placed on the rotating fixture of the machine i.e. rotor as shown in the ... of rotor used in construction of alternator, 1. Salient pole type. 2. Cylindrical rotor type. 

The driving power from the prime-mover driving the alternator is lost but the alternator remains connected

Description :  The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will: A) ... as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action 

Last Answer : The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will: behave as a synchronous motor and will rotate in the same direction

Which alternator will have more number of poles ?

Description : Which alternator will have more number of poles ? (a) coupled to steam turbine (b) coupled to gas turbine (c) coupled to hydraulic turbine (d) None of the above 

Last Answer : b

A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a

Description : A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A is  (A) 1 V (B) 10 V (C) 100 V (D) 1000 V

Last Answer : 800

At which power factor alternator is said to be overexcited?

Description : At which power factor alternator is said to be overexcited?

Last Answer : At leading power factor alternator is said to be overexcited.

The power factor of an alternator depends on?

Description : The power factor of an alternator depends on?

Last Answer : The power factor of an alternator depends on load.

In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

Description : In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

Last Answer : In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.

The magnitude of various voltage drops that occur in an alternator depends on?

Description : The magnitude of various voltage drops that occur in an alternator depends on?

Last Answer : The magnitude of various voltage drops that occur in an alternator depends on load current.

In alternator where the voltage drop occurs?

Description : In alternator where the voltage drop occurs?

Last Answer : In alternator voltage drop occurs in armature resistance, leakage reactance, and armature reactance.

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

Salient pole rotor is use for which speed?

Description : Salient pole rotor is use for which speed?

Last Answer : Salient pole rotor is use for low and medium speed prime movers.

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

The pole star does not seem to move because (a) it is in line with the earth’s axis of rotation (b) it moves around the sun and not the earth (c) its movement can be seen only during a solar eclipse (d) it rotates very rapidly

Description : The pole star does not seem to move because (a) it is in line with the earth’s axis of rotation (b) it moves around the sun and not the earth (c) its movement can be seen only during a solar eclipse (d) it rotates very rapidly

Last Answer : Ans:(a)

What is the pitch factor of a 4 pole alternator having 36 slots and a coil span of 1 to 8?

Description : What is the pitch factor of a 4 pole alternator having 36 slots and a coil span of 1 to 8?  (A) 140° (B) 80° (C) 20° (D) 40°

Last Answer : C

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

If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of...

Description : If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of 400 rps. The frequency of the induced output voltage will be: A. 40 Hz B. 100 Hz C. 400 Hz D. indeterminable

Last Answer : If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of 400 rps. The frequency of the induced output voltage will be: 400 Hz

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 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

A four-pole induction motor, operating on three-phase 60 cycle current will operate at approximately ___________. A. 850 RPM B. 1,150 RPM C. 1,750 RPM D. 3,550 RPM

Description : A four-pole induction motor, operating on three-phase 60 cycle current will operate at approximately ___________. A. 850 RPM B. 1,150 RPM C. 1,750 RPM D. 3,550 RPM

Last Answer : Answer: C

A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, the new discharge will be __________ litres/minute. (A) 500 (B) 200 (C) 1000 (D) 750

Description : A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, the new discharge will be __________ litres/minute. (A) 500 (B) 200 (C) 1000 (D) 750

Last Answer : (A) 500

What are the prime movers used for a) Salient pole alternator, b) Non- salient pole alternator.

Description : What are the prime movers used for a) Salient pole alternator, b) Non- salient pole alternator.

Last Answer : The prime movers used for salient pole alternators are water wheels likeKaplan turbine, Francis turbine, Pelton wheel etc., and diesel or petrol engines. The prime movers used for non-salient pole alternators are steam turbines and gas turbines.

The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is:

Description : The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is: A) 360 degree B) 720 degree C) 1080 degree D) 2160 degree

Last Answer : 1080

Slip test is performed to determine : (A) Slip in an induction motor vtkgi Xd and Xq in a salient pole alternator

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 

The voltage regulation of an alternator having 0.75 leading p.f. load, no-load induced e.m.f. of 2400V and ...

Description : The voltage regulation of an alternator having 0.75 leading p.f. load, no-load induced e.m.f. of 2400V and rated terminal voltage of 3000V is —————————————  A) 20% B) —20% C) 150 D) -26.7

Last Answer : -20

A goodstrain of 700 m runs at a speed of 165 km/hr. A person traveling in it observes that the mail train moving in opposite direction takes 30 seconds to cross him. Find the speed of the mail train, if it is 750 m long. A) 8.4 m/s B) 5.3 m/s C) 2.5 m/s D) 6.8 m/s

Description : A goodstrain of 700 m runs at a speed of 165 km/hr. A person traveling in it observes that the mail train moving in opposite direction takes 30 seconds to cross him. Find the speed of the mail train, if it is 750 m long. A) 8.4 m/s B) 5.3 m/s C) 2.5 m/s D) 6.8 m/s

Last Answer : ANSWER:C Explanation:  Speed of goods train = 165km/hr  length of mail train (P) = 750m  length of goods train (Q) = 700m  Alternately, we can directly use the formula:  Time = ( p+q) / (v1+v2) sec  ( ...  45.833+v2 = 48.333  V2 = 2.5 m/s  Therefore the speed of the mail train is 2.5 m/s

A disc of radius R rotates with constant angular velocity `omega` about its own axis. Surface charge density of this disc varies as `sigma = alphar^(2

Description : A disc of radius R rotates with constant angular velocity `omega` about its own axis. Surface charge density of this disc varies as `sigma = alphar^(2

Last Answer : A disc of radius R rotates with constant angular velocity `omega` about its own axis. Surface charge density of ... D. `(mu_(0)alphaomegaR^(3))/(3)`

In an AC dynamo, the speed at which the coil rotates is doubled. How would this affect a) the frequency of output voltage b) the maximum output voltage?

Description : In an AC dynamo, the speed at which the coil rotates is doubled. How would this affect a) the frequency of output voltage b) the maximum output voltage?

Last Answer : a) Frequency is doubled b) Maximum output voltage is doubled.

In Induction motor Slip frequency of rotor current, when rotor speed is Nr. Then rotor producing slip field rotates with respect to stator is a) Slip frequency b) Nr c) Ns d) None

Description : In Induction motor Slip frequency of rotor current, when rotor speed is Nr. Then rotor producing slip field rotates with respect to stator is a) Slip frequency b) Nr c) Ns d) None

Last Answer : Ans: Ns

While placing of concrete the thickness of each layer for R.C.C. is [ A ] 150 to 300 mm [ B ] 450 mm [ C ] 500 to 750 mm [ D ] 500 mm

Description : While placing of concrete the thickness of each layer for R.C.C. is [ A ] 150 to 300 mm [ B ] 450 mm [ C ] 500 to 750 mm [ D ] 500 mm

Last Answer : [ A ] 150 to 300 mm

A 2 m long shaft rotates about one end at 20 rad/s. It begins to accelerate with ? = 10 rads/s2. After how long, in seconds, will the velocity of the free end reach 100 m/s? a.3 b.107 dynes c.5 d.6 e.7

Description : A 2 m long shaft rotates about one end at 20 rad/s. It begins to accelerate with ? = 10 rads/s2. After how long, in seconds, will the velocity of the free end reach 100 m/s? a.3 b.107 dynes c.5 d.6 e.7

Last Answer : a. 3

When the armature of a D.C. motor rotates, e.m.f. induced is

Last Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

Two 3-phase, Y-connected alternators are to be paralleled to a set of common busbars. The armature has a

Description : Two 3-phase, Y-connected alternators are to be paralleled to a set of common busbars. The armature has a per phase synchronous reactance of 1.7 Ohm and negligible armature resistance. The line voltage of the first machine is adjusted to ... will be  (A) 16.98 A (B) 29.41 A (C) 33.96 A (D) 58.82 A

Last Answer : Two 3-phase, Y-connected alternators are to be paralleled to a set of common busbars. The armature has a per phase synchronous reactance of 1.7 Ohm and negligible armature resistance. The ... instant they are paralleled. Under this condition, the synchronizing current per phase will be 16.98 A

Which rotor is use for high speed in turbo alternators?

Description : Which rotor is use for high speed in turbo alternators?

Last Answer : Non-salient pole rotor is used for high speed in turbo alternators.

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

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

Two observation wells penetrating into a confined aquifer are located 1500 m apart in the direction of flow. Heads of 50 m and 25 m are indicated at these two observation wells. If the coefficient of permeability for the aquifer is 30 m/day and its porosity is 0.25, the time of travel of an inert tracer from one well to another is (a) 75 days (b) 750 days (c) 1200 days (d) 3000 days

Description : Two observation wells penetrating into a confined aquifer are located 1500 m apart in the direction of flow. Heads of 50 m and 25 m are indicated at these two observation wells. If the coefficient of permeability for the ... well to another is (a) 75 days (b) 750 days (c) 1200 days (d) 3000 days

Last Answer : (b) 750 days

A change in field excitation of an alternator operating in parallel will cause a change in its _____________. A. alternator frequency B. kilowatt load C. voltage output D. all of the above

Description : A change in field excitation of an alternator operating in parallel will cause a change in its _____________. A. alternator frequency B. kilowatt load C. voltage output D. all of the above

Last Answer : Answer: C

Is 75000 m is equal to 750 km?

Description : Is 75000 m is equal to 750 km?

Last Answer : No! 75,000 metres are 75 kilometres.Note, there are 1,000 metres in 1 kilometres.

How do i Calculate the metres of perimeter of a square with sides 2.750 m long?

Description : How do i Calculate the metres of perimeter of a square with sides 2.750 m long?

Last Answer : multiply by 2.75m by 4

Is 75000 m is equal to 750 km?

Description : Is 75000 m is equal to 750 km?

Last Answer : No! 75,000 metres are 75 kilometres.Note, there are 1,000 metres in 1 kilometres.

Speed of sound in water is 1500 m s-1, depth of water when reflected sound waves are detected after 0.40 s is A. 700 m B. 600 km C. 600 m D. 750 km

Description : Speed of sound in water is 1500 m s-1, depth of water when reflected sound waves are detected after 0.40 s is A. 700 m B. 600 km C. 600 m D. 750 km

Last Answer : 600 m