Siemens 8DJH Series Installation And Operating Instructions Manual page 51

Example
500-8067.9 * INSTALLATION AND OPERATING INSTRUCTIONS 8DJH * Revision 03
Rated voltage (r.m.s. value)
Rated short-duration power-frequency withstand voltage (r.m.s. value)
- Across isolating distances
- Between phases and to earth
Rated lightning impulse withstand voltage (peak value)
- Across isolating distances
- Between phases and to earth
Fig. 34: Correction factor K
Rated short-duration power-frequency withstand voltage to be selected for site altitudes > 1000 m
≥ Rated short-duration power-frequency withstand voltage up to ≤ 1000 m * Ka
Rated lightning impulse withstand voltage to be selected for site altitudes > 1000 m
≥ Rated lightning impulse withstand voltage up to ≤ 1000 m * K
Example
3000 m site altitude above sea level
17.5 kV switchgear rated voltage
95.0 kV rated lightning impulse withstand voltage
Rated lightning impulse withstand voltage to be selected
95 kV * 1.28 = 122 kV
Result
According to the above table, a switchgear for a rated voltage of 24 kV with a rated lightning impulse withstand voltage of
125 kV is to be selected.
[kV]
[kV]
[kV]
as a function of the site altitude in m above sea level
a
a
7.2 12 15 17.5
23 32 39 45
20 28 36 38
70 85 105 110
60 75 95 95
Description
24
60
50
145
125
51