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The volume of the conservator should be such, that there is oil left in the conservator
even at the lowest oil temperature expected and such that no flooding can occur at the
highest oil temperature expected. Even transformers with more than one on-load tap-
changer unit require only one conservator.
A suitable dimension of the tube for connection to the conservator is an innerdiameter
of approximately 20 mm. The tube should be inclined at least 3 degrees to avoid gas
cushions in the tube. A valve in the connection to the conservator is recommended.
The conservator must be equipped with a breathing device that does not allow moist air
into the conservator and that allows the gas from the arcs to disappear.
The conservator should also be equipped with an oil level indicator and an alarm
contact for low oil level is recommended.
1.6 Oil Filter Unit for Continuous
Oil Filtration
If the on-load tap-changer should have an oil filter unit for continuous oil filtration
from ABB, installation and commissioning instructions are found in the manual for the
oil filter unit, Oil filter unit for On-Load Tap-Changers, Manual delivered with the
oil filter unit.
1.7 Weights
Motor-drive mechanism BUE 1 weight: approximately 130 kg
Motor-drive mechanism BUE 2 weight: approximately 155 kg
The weights of the motor-drive mechanism and drive-shaft system are not included in
the weights given on next page.
1 Introduction