Page 641 - Industrial Power Engineering and Applications Handbook

18/606 Industrial Power Engineering and Applications Handbook
* +
I Primary transmission Secondary
I (132,220 or 400 kV) i transmission
L
0'
Isolated phase bus ' ! Jumper or c
ml
JumDer rnhlp

TraAsferred I Direct surges in l a I
t surges - both directions -4 (a) They may be transferred surges i
0 Occurrence of from HV side or
likely surges: I
~ (b) Direct surges on the LV side in
both directions
I Conventional shape is shown, but amplitude as well as shape will vary
@ Shape 1 depending upon the type of surge and Zs of line and equipment
I Lightning, switching or steep fronted (FOW), depending upon the
I
@ Type of surges I system voltage and switching conditions
50 300, I 30 I , I I I 40 , I ~ 2001 I
I I I i 300i I I 1
I ,
I I I I I I
@ Effect of low 1 v. high low low v. high low
reflections and I
refractions
[Not to be I
considered
where arrester
is provided] ' Indoor 1 I
Indoor and Outdoor Outdoor Outdoor Outdoor Outdooi
partly
@ Exposure to I outdoor 1
atmosphere
Station class Station class
@ Type of arrester
@ Check effect
of surge
transferences:
L For all voltages c
(1) Capacitive - k

(2) Inductive For systems up to 245 kV
Note:
1. Transferences from LV to HV side are not significant and need not be considered.
2. Transferences need not be considered when arrester is provided on the LV side.
a,
@ Check for b- For critical installations up to 245 kV ._ - c
resonance effects

J

* Values are only indicative to assess the likely reflections at different junctions.
Obtain accurate values from the equipment manufacturers.

Figure 18.15 (contd.)