Page 100 - Electric Machinery Fundamentals

7 6 ELECTRIC MACHINERY FUNDAMENTALS

V=480 L OOV I linc 0.18n jO.24 n
.AA
1 : 10 vvv ,
,
• , I
,
Z JiBe
, '
Zload=:
,
400+ j300n
,
, I
I
I
(a)
: Equivalent circuit
0.0018 n jO.0024n

(
Z'linc

Equivalent circuit
(b)

FIGURE 2-7
(n) System with the load referred to the transmission system voltage level. (b) System with the load
aod transmission line referred to the generator's voltage level.

Working back through T2 gives
N n1linc = N.S1Iload
Np2
1 10ntl = NS2 l line
o
o
~ \0 (9.S94 L - 36.SS A) ~ 9S.94 L - 36.SS A
It is now possible to answer the questions originally asked. The load voltage is given by
Vlu~d = I lood ~oad
o
~ (9S.94 L - 36.SS A)(S L36.S7° !l)
~ 479.7 L - O.O lo V
and the line losses are given by

Ploss = (/1ine)2R line
~ (9.S94 A)2 (O.lS !l) ~ 16.7 W
Notice that raising the transmission voltage of the power system reduced
transmission losses by a factor of nearly 90' Also, the voltage at the load dropped
much less in the system with transformers compared to the system without