5 Mounting
Maschinenfabrik Reinhausen GmbH 2020
61
4983703/01 EN
VACUTAP
®
VV-Ex
When actuating the change-over selector, a higher torque is required.
1. Switch the on-load tap-changer into the desired operating position. The di-
verter switch operation can be heard distinctly.
2.
NOTICE!
An incomplete tap-change operation may damage the on-load
tap-changer. After operating the diverter switch, continue to crank the
drive shaft of the upper gear unit for 2.5 revolutions in the same direction
in order to correctly complete the tap-change operation.
3. Perform the transformer ratio test.
4. Repeat the transformer ratio test in all operating positions.
5. Switch the on-load tap-changer into adjustment position (see the accom-
panying connection diagram for the on-load tap-changer).
After the transformer ratio test, open the kerosene drain plug in the oil com-
partment if the on-load tap-changer is to be dried with kerosene in the trans-
former tank. After drying, the diverter switch insert must be removed, the
kerosene drain plug in the oil compartment closed and the diverter switch
insert refitted.
5.4.4 Performing DC resistance measurement on transformer
The measured DC current is normally restricted to 10% of the rated current
of the measured transformer winding in order to prevent the winding from
overheating.
Perform the DC resistance measurement in various on-load tap-changer op-
erating positions. You need to distinguish here whether the measured cur-
rent is interrupted when changing operating position or not.
Status of oil compart-
ment
Without interruption in
measured current
With interruption (mea-
sured current = 0 A be-
fore change of operating
position)
Oil compartment empty
Maximum 10 A DC
Maximum 50 A DC
Oil compartment filled with
insulating fluid
Maximum 50 A DC
Maximum 50 A DC
Table 12: Maximum permitted measured currents when performing DC resistance measurement
on transformer
