Alternators

A winding is short pitched by 60 degrees electrical. Its pitch factor is:

Two exactly similar turbo-alternators are rated 5 MW each. They are running in parallel. The speed load characteristics of the driving turbines are such that the frequency of alternator one drops uniformly from 60 Hz on no-load to 57.5Hz on full-load, that of alternator two from 60 Hz to 58 Hz. How will two machines share a load of 8,000 kW?

In a 10-pole synchronous machine, 20 electrical degrees are equivalent to how many mechanical degrees?

Calculate the average voltage generated in a six-turn full-pitch coil of a 25-cycle alternator if the flux per pole is \(7.2 \times 10^{5}\) maxwells.

For proper parallel operation, ac polyphase alternators must have the same ______

A two-pole, three-phase, 50 Hz star connected ac generator has 9 slots/pole and 6 conductors/slot. What is the flux per pole if the open circuit terminal voltage is 1,100 volts? Take the coil span as unity.

A 500 kVA alternator operates at 80% of full load with an efficiency of 92 percent. If the load power factor is 0.8, calculate the total loss.

A three-phase, wye-connected, 6.25 kVA, 220-volt synchronous generator has a reactance of 8.4 ohms per phase. Using the rated kVA and voltage as base values, determine the per unit reactance.

A two-pole alternator is running at 1,500 rpm. What is the angular velocity?

At leading p.f., the armature flux in an alternator ________ the rotor flux.

Calculate the effective voltage in one phase of an alternator, given the following particulars: f = 60 cps; turns per phase N = 240; flux per pole = \(2.08 \times 10^{6}\) maxwells.

The power factor of an alternator is determined by its

A three-phase 60 Hz wye-connected wound rotor synchronous generator rated at 10 kVA, 230V has a synchronous reactance of 1.2 ohm per phase and an armature resistance of 0.5 ohm per phase. Calculate the percent regulation at full-load with 0.8 lagging power factor.

For coil having a span of 2/3 of pole pitch, the coil span factor is

In a 6-pole alternator how many mechanical degrees is the equivalent of 180 electrical degrees?

For two alternators operating in parallel, if the load shared by one of them is to be increased, its field excitation is

The field system of a 50 Hz alternator has a sinusoidal flux per pole of 0.1 Wb. Calculate the emf generated in one turn which spans two-thirds of a pole pitch.

What is the function of the damper windings in a large alternator?

The distribution of load between two alternators in parallel operation is changed using one of the following methods?

The drop in the terminal voltage of an alternator due to armature reaction is countered by which of the following?