5 Mounting
Maschinenfabrik Reinhausen GmbH 2020
53
4983703/01 EN
VACUTAP
®
VV-Ex
2. Increase the kerosene vapor temperature by approx. 10°C/hour to the de-
sired final temperature of max. 125°C at the on-load tap-changer.
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.
►
NOTICE!
Close kerosene drain plug clockwise (tightening torque 39 Nm).
An open kerosene drain plug leads to oil escaping from the oil compart-
ment and therefore to damage to the on-load tap-changer and trans-
former.
5.3.6 Drying on-load tap-changer in transformer tank
Dry on-load tap-changer in accordance with the following instructions to en-
sure the dielectric values assured by MR on the on-load tap-changer.
If you want to dry the on-load tap-changer in the transformer tank, fully as-
semble the transformer first and then undertake drying.
If drying in the transformer tank, the following methods are possible:
▪ Vacuum-drying
▪ Vapor-phase drying
As an alternative to drying the on-load tap-changer in the transformer tank, it
can also be dried in an autoclave.
5.3.6.1 Vacuum-drying in the transformer tank
The on-load tap-changer head cover remains closed during the entire drying
process.
1. Establish a connecting lead between either connections E2 and Q or con-
nections E2 and R on the on-load tap-changer head.
