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Sesto San Giovanni, MI 20099 Italy
Tel. 02-24105.001
IS 2653 GB
Page
10
of
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Gas SF6 characteristics and gas filling instruction
The SF6 gas to be used to fill the bushing must comply with the data shown in the following
Table 1
. This table
shows the limits stated by GE Grid Solutions RPV specification and the characteristics of a premium Supplier:
Characteristics
Unit
GE RPV limits
Premium
Supplier’s limits
Min SF6
% by weight
≥
99.9%
≥
99.993%
Air
ppm by weight
≤
500 ppm
≤
50 ppm
CF4
ppm by weight
≤
500 ppm
≤
10 ppm
H
2
O
ppm by weight
≤
15 ppm
≤
0.65 ppm
Mineral oil
ppm by weight
≤
10 ppm
≤
1 ppm
Total acidity expressed in HF
ppm by weight
≤
0.3 ppm
≤
0.3 ppm
Hydrolizable fluorides in terms of HF
ppm by weight
≤
1 ppm
≤
1 ppm
Table 1 - Characteristics of new SF6 gas according to GE Grid Solutions RPV and premium Supplier
The minimum requirement is that the characteristics will be in accordance with the data listed in the GE RPV
limits column.
The gas filling must be performed with an equipment that prevents dispersion of the SF6 gas in the
atmosphere. As an example, next
Figure 8
shows a gas plant manufactured by the German company DILO
GmbH.
Figure 8 – Vacuum filling gas plant DILO and connecting valves
NOTE:
This bushing has to be operated with pure SF6. In case of need of replacement of SF6 gas with a
mixture SF6 N2, before to proceed, please contact GE Grid Solutions RPV for instructions and approval.
CAUTION: The following safety notes are mandatory.
•
The bushing can be filled at the rated filling pressure only when installed on the valve hall wall.
•
If, for any reason, the bushing has to be removed from the wall, it is mandatory to reduce the gas
pressure to 0.14 MPa abs (0.4 bar gauge), before proceeding with the operation.
•
All gas filling and gas recovering operations must be performed by a gas plant device (example a DILO
machine).
