11
1ZSE 5492-118 en, Rev. 4
1.1 Required tools
■
Air pump with hose, pressure gauge (0-250 kPa) and connection with internal thread
R 1/8”
■
Normal set of open end wrenches (up to 19 mm)
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Normal set of sockets (up to 19 mm)
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Socket handle
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Socket extender
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Normal set of screw drivers
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Allen key sockets 5 and 6 mm
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Lifting bar LL 117 016-K (yoke-mounting only)
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Dynamometric wrenches, 5-85 Nm
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Bottom valve key (delivered with the on-load tap-changer)
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Tool for opening of oil drum
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Hack saw
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Bucket, 10 litres
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Lifting jack
1.2 Required material
■
Grease, (Ball bearing grease) GULF-718 EP, Mobil-Grease 28, SHELL-Aero Shell
Grease 22 or similar
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Equipment for oil filling
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Sealing tape
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Rags (non-fuzzying) for cleaning
1.3 Oil
The oil quality should be of Class II according to IEC publication 60296. The oil weight ac-
cording to table 1 in section 1.6.
WARNING
Do not energize the transformer until oil has been filled according to chapter 7, Oil
Filling in this guide.
1.4 Oil conservator
The on-load tap-changer has to be connected to an oil conservator. ABB recommends the
use of a separate conservator for the on-load tap-changer with both oil and air side sepa-
rated from the main conservator of the transformer.
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 inner diameter 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 Introduction