# 3 Phase Y Connected Generator

Discussion in 'Homework Help' started by richDFC, Nov 25, 2012.

1. ### richDFC Thread Starter New Member

Nov 25, 2012
1
0
Hi guys.

Got a question for a tutorial sheet we're doing and can't rap my head around the values I've worked out.

heres the question

A Y connected, 400V (line), 100KVA rated, stand alone generator is operating at 80kW at rated current with a lagging power factor and rated terminal voltage. The synchronous reactance is 2Ω.

Draw the per phase equivalent circuit and calculate:

(i) The Phase Current (Iph)
(ii) The Power Factor
(iii) The Reactive Power
(iv) The Voltage drop across the Synchronous Reactance (VXS)

So I've drawn the per phase equivalent circuit.

I then calculated the phase voltage by Vph = Vline / root3 to get a value of 230.9V

Iph was then found from S (apparent power) = IV rearrange to get I = 57735 (per phase power)/230.9

This gives a value of Iph as 250A which seems slightly high.

Continuing on i find power factor to be 0.8 from P = IVcostheta where costheta is the power factor.

The problem comes when I calculate part iv the voltage drop.

I used Vxs = Iph * jXs (j being imaginary number) but this gives a value of 500V which is greater than Vph.

Any help is much appreciated!