# Homework Help: Synchronous machine help

1. Jun 23, 2009

### mayeh

1. The problem statement, all variables and given/known data
1. A 4MVA, 13.3kV, 60Hz, 3 phase, delta-connected alternator has an effective resistance of 5.2 ohm/phase and a combined armature reactance of 54 ohm/phase. Determine the full-load generated voltage per phase, a. At unity pf, b. at 0.8 pf lagging, and at 0.866 leading pf.

2. A 750kVA, 2300V, delta-connected, 3-phase alternator has had open and short circuit tests performed and the following date were obtained:

Short Circuit test

Field current = 31.5A
Line current = rated

Open-circuit test

Field-current = 31.5A
Line voltage=1050V

The dc resistance across the terminals was measured at 0.38 ohm. Calculate the V.R. at 0.8pf lagging.

3. Calculate the open circuit votlage of a 3phase, star-connected alternator, 4 pole, 60Hz, 120 slots with each slot having 6 conductors in two layers. The machine is running at 1800rpm with a flux per pole of 125 milliWeber. The coil span is 12.

4. A single phase alternator, 50kVA, 460V supplies the rated load at 0.88 pf lagging. The dc resistance across the terminals is 0.5 ohm and the synchronous reactance is 2.5 ohm. Calculate the angle of the power.

2. Relevant equations

no idea.

3. The attempt at a solution1. The problem statement, all variables and given/known data