7 Maintenance
Maschinenfabrik Reinhausen GmbH 2020
47
5993419/02 EN
VACUTAP
®
VMS
®
7.1 Inspection
Monitoring the on-load tap-changer and motor-drive unit is limited to occa-
sional visual checks of the on-load tap-changer head, protective relay and
motor-drive unit, as well as monitoring the quality of the insulating fluid. For
efficiency reasons these visual inspections can be combined with the usual
checks on the transformer.
Check the following:
Interval
Action
Annually
Check door seal, cable bushings, and ventilation of protective
housing of motor-drive unit/control cabinet.
Annually
Check sealing points of on-load tap-changer head, protective
relay, and connected pipes.
Annually
Check correct functioning of the installed electrical heater in
the protective housing of the motor-drive unit/control cabinet.
Annually
Check correct function of protective relay [
Annually
Check perfect condition of the silica gel breather for the on-
load tap-changer oil conservator.
Every 2 years
Check the quality of the insulating fluid of on-load tap-chang-
ers that are installed in positions other than the neutral point of
windings (Class 2 in accordance with 60214-1).
1. Take a sample of insulating fluid from the oil compartment.
2. Record the temperature of the sample (insulating fluid) im-
mediately after the sample is taken.
3. Determine dielectric strength and water content at an insu-
lating fluid temperature of 20 °C ± 5 °C. The dielectric
strength and water content must comply with the limit val-
ues specified in the technical data.
4. If the limit values are not complied with, change the insulat-
ing fluid in accordance with the "Changing the insulating
fluid" section.
Every 7 years
Check the quality of the insulating fluid of on-load tap-chang-
ers that are installed at the neutral point of windings (Class 1
in accordance with 60214-1).
1. Take a sample of insulating fluid from the oil compartment.
2. Record the temperature of the sample (insulating fluid) im-
mediately after the sample is taken.
3. Determine dielectric strength and water content at an insu-
lating fluid temperature of 20 °C ± 5 °C. The dielectric
strength and water content must comply with the limit val-
ues specified in the technical data.
4. If the limit values are not complied with, change the insulat-
ing fluid in accordance with the "Changing the insulating
fluid" section.
Table 5: Inspection plan
