5 Mounting
Maschinenfabrik Reinhausen GmbH 2020
54
4983703/01 EN
VACUTAP
®
VV-Ex
2. Seal off unused pipe connections and pipe bends with a suitable blank
cover.
Figure 29: Connecting lead
Vacuum-drying in the transformer tank
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.
5.3.6.2 Vapor-phase drying in the transformer tank
If you have opened the kerosene drain plug already (e.g. after the trans-
former ratio test), you can begin the drying right away.
Otherwise, you first have to open the kerosene drain plug before you can be-
gin the drying.
1. Remove on-load tap-changer insert. Please request the documents for re-
moval from Maschinenfabrik Reinhausen GmbH.