5 Mounting
Maschinenfabrik Reinhausen GmbH 2020
140
7545652/00 EN
VACUTAP
®
VR-Ex
3. Remove on-load tap-changer head cover.
Figure 144: On-load tap-changer head cover
5.4.5.1.3 Drying the on-load tap-changer
NOTICE
Damage to the on-load tap-changer head cover and on-load tap-
changer accessories.
Both the on-load tap-changer head cover and the on-load tap-changer ac-
cessories will become damaged if they are dried.
► Never dry the on-load tap-changer head cover or the following acces-
sories: motor-drive unit, drive shaft, protective relay, pressure monitoring
device, pressure relief device, bevel gear, temperature sensor, oil filter
unit.
1. Heat up the on-load tap-changer in air at atmospheric pressure with a
temperature increase of approximately 10 °C/h to a final temperature of
maximum 110 °C.
2. Pre-dry the on-load tap-changer in circulating air at a maximum tempera-
ture of 110 °C for a period of at least 20 hours.
3. Vacuum-dry on-load tap-changer at between 105 °C and maximum
125 °C for at least 50 hours.
4. Residual pressure of no more than 10
-3
bar.
5.4.5.1.4 Securing on-load tap-changer head cover
NOTICE
Damage to the on-load tap-changer!
A missing or damaged o-ring as well as unclean sealing surfaces lead to in-
sulating fluid escaping and therefore to damage to the on-load tap-changer.
► Ensure that the o-ring is positioned untwisted in the on-load tap-changer
head cover.
► Ensure that the o-ring does not become damaged when mounting the
cover.
► Ensure that the sealing surfaces on the on-load tap-changer head cover
and on-load tap-changer head are clean.