Page 598 - Industrial Power Engineering and Applications Handbook

Voltage surges-causes, effects and remedies 171563
10000

= 3000 R
5 3500 $2 +

1000
--.
w
N
k?
a,
C
-2
.- F
a,
?
v)
100

10
0.01 0.1 1 .o 10.0
500 kVA (6.6 kV)
MVA _t
m
Figure 17.7(a) Surge impedance of rotating machines as a function of input MVA/,,~ (from Pretorious and Eriksson, 1982)

33 kV 66 kV 11 kV
Motors Motors Motors

‘i

-

E
LV
t-
kW -
io 20 50 102 zoo 103 2000 5000 io4
0 500
500 kVA
Figure 17.7(b) Typical value rating of equipment of surge Figure 17.7 (c) Surge impedance of HT motors as a function of
impedances for HT motors and transformers output power

The magnitude of the TRV, which is the product of curves have been established with the help of the curves
Z, x IJI, being the current chopped), can be determined in Figures 17.7(a) and (b) and the values of I,. assumed
with the help of curves shown in Figure 17.8. These for various types of interrupters. The curves in Figures