ABB 2769522-C, Installation And Maintenance Manual

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Installation and maintenance guide
1ZSC000563-ACD EN, REV. A, 2019-06-25
9
2.2 Usage
Overview
Use the test adapter only as described in this installation and maintenance guide, and obey the limitations of
the test adapter. Refer to
Description and limitations of the tap, page 9 .
Grounding
The tap is not self grounding, and must always be grounded or connected to an external impedance. Because
C
2
usually is relatively small, the test tap must never be open-circuited when the bushing is energized.
If the tap is not grounded when the bushing is energized, failure of the bushing will occur.
CAUTION!
Do not energize the bushing without a test adapter or the cover installed. The bushing is grounded
through the cover to prevent damage to the bushing.
2.3 Description and limitations of the tap
Overview
The values of impedance for the main insulation and the tap are unique to every bushing. Refer to the rating
plate on the bushing or to the bushing installation and maintenance guide.
The value of the capacitance C
2
depends on the design of the bushing and on its installation, and can thus
vary more or less. The capacitance C
2
should be measured after installation of the bushing, to get an accurate
value.
CAUTION!
Do not connect a circuit that overloads test adapter. This will lead to partial discharge in the
bushing, which will cause damage to the bushing.
NOTE!
The test adapter limits the amount of power that can be passed through the tap, despite a higher
capacity of the tap.
G000748
* The connected circuit is the equipment and cables that are connected to the test adapter.