Description
9229 0106 176 0-
23
2020-09-18
Installation altitudes
As standard, 3TM vacuum contactors can be used at -1250 m to +2000 m. For high-
er operation heights, a configuration from 2000 m to 5000 m can be ordered.
Dielectric strength
The dielectric strength of insulation in air declines with rising altitude increases due
to the lower air density. As per IEC 62271-102, the rated lightning impulse voltage
values given in Fig. 15 are valid up to an installation altitude of 1000 m above sea
level.
Above an altitude of 1000 m, the insulation level must be corrected as shown in
Fig. 19:
Note
The installation altitude for the vacuum contactor is set at the factory according
to the ordering option.
U
U
0
x
K
a
U Rated withstand voltage U under standard reference
atmosphere
U
0
required rated withstand voltage for the installation
location
K
a
Altitude correction factor
K
a
= e
m x
(H - 1000)/8150
Calculation of the altitude correction factor
K
a
:
H
=
Installation altitude in metres
m = 1 for AC voltage, lighting impulse voltage (between
phases, phase-to-earth, applied longitudinally)
Example
For a required rated withstand voltage of 75 kV at an al-
titude of 2,500 m, an insulation level of at least 90 kV un-
der standard reference atmosphere conditions is
required:
90 kV
75 kV x e
1 x
(2500 - 1000)/8150
75 kV x 1.2
Fig. 19
Altitude correction factor
K
a
Summary of Contents for 3TM
Page 12: ...Transport storage packaging 12 9229 0106 176 0 2020 09 18 Blank page ...
Page 26: ...Description 26 9229 0106 176 0 2020 09 18 Blank page ...
Page 36: ...Installation 36 9229 0106 176 0 2020 09 18 Blank page ...
Page 48: ...Maintenance 48 9229 0106 176 0 2020 09 18 Blank page ...
Page 50: ...Index 50 9229 0106 176 0 2020 09 18 Blank page ...