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# Alternator

## Related questions

What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these

While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then (A) It would over-run the other alternator (B) Its rotor will fall back in phase with respect to the other machine (C) Its portion of share in load will increase (D) Its power factor would be decreased.

The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7

Is the speed of alternator is directly proportional to frequency?

At which power factor alternator is said to be overexcited?

The power factor of an alternator depends on?

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

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

In alternator where the voltage drop occurs?

What causes diodes to fail in alternator?

AC power plugs and sockets

Synchronous vs asynchronous logic

Analog signal

Ammeter

Alternating current

Audion

Austin transformer

Transfer switch

Automation

Recloser

Autotransformer

Availability factor

Avalanche diode

Electrical engineering

Average rectified value

AC power

State any four salient features of turbo- alternator.

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

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

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

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) get burnt B) behave as an induction motor but will rotate in the opposite direction C) behave as a synchronous motor and will rotate in the same direction D) behave as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action

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

A 20-MVA, 6.6-kV, 3-phase alternator is connected to a 3-phase transmission line. The per unit positive-sequence, negative-sequence and zero-sequence impedances of the alternator are j0.1, j0.1 and j0.04 respectively. The neutral of the alternator is connected to ground through an inductive reactor of j0.05 p.u. The per unit positive-, ... The voltage of the alternator neutral with respect to ground during the fault is  (A) 513.8 V (B) 889.9 V (C) 1112.0 V (D) 642.2 V

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

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

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

The type of alternator used in hydroelectric power stations is

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

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.

In wound rotor alternator, reactive power is maximum at a load angle of

Potier reactance of an alternator is almost the same as   (a) Field winding reactance (b) Total armature reactance (c) Leakage reactance of field winding (d) Armature leakage reactance

In a 3 -phase alternator, if there is only magnetizing armature reaction, the load is :  (A) capacitive (B) inductive (C) resistive (D) inductive and resistive