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8
Gas SF6 characteristics and gas filling instructions
The SF6 gas to be used to fill the bushing must comply with the data shown in the following Table 14. This table
shows the limits stated by GE Energy Connections RPV specification and the characteristics of a Premium
Supplier:
Characteristics
Min SF6
Air
CF4
H
O
2
Dew point @ atmospheric pressure
Mineral oil
Total acidity expressed in HF
Hydrolizable fluorides in terms of HF
Table 14 - Characteristics of new SF6 gas according GE Energy Connections RPV and premium
The minimum requirement is that the characteristics have to be in accordance with the data listed in the GE
Energy Connections RPV limits column.
Before proceeding with filling or re-filling operations the gas characteristics must be checked and the data must
be reported in the Gas filling check list, see Appendix 8.
The gas filling must be performed with an equipment that prevents dispersion of the SF6 gas in the atmosphere.
As an example, next Figure 14 shows a gas plant manufactured by the German company DILO GmbH.
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 proceeding, please contact GE Energy Connections RPV for instructions and approval.
WARNING: The following safety notes are mandatory.
The bushing can be filled at the rated filling pressure of 0.63 MPa abs (5.3 bar gauge @ 20° C), only
•
when installed on the transformer ready for the electrical tests or placed inside valve hall wall.
If, for any reason, the bushing has to be removed from the transformer turret, it is mandatory to
•
reduce the gas pressure to 0.125 MPa abs (0.25 bar gauge) before proceeding with the operation.
If the transformer is stored with the bushings installed, the gas pressure must be reduced to 0.150 MPa
•
abs (0.5 bar gauge) and periodically checked.
All gas filling and gas recovering operations must be performed by a gas plant device (example a DILO
•
machine).
WARNING: Before proceeding with the gas filling operation, remove the Transport pressure gauge (see
Paragraph 3.1 and Figure 1).
HVDC TRANSFORMER BUSHINGS
PHI 530.1425.2500
PHI 265.850.1500
Kepco project
Unit
% by weight
ppm by weight
ppm by weight
ppm by weight
° C
ppm by weight
ppm by weight
ppm by weight
Supplier
Figure 14 – Vacuum filling gas plant DILO
IS 2664 GB
Page 24 of 70
GE Energy
Connections RPV
Supplier's limits
limits
≥99.9%
≤500 ppm w
≤500 ppm w
≤15 ppm w
≤-40° C
≤10 ppm w
≤0.3 ppm w
≤1 ppm w
Premium
≥99.993%
≤50 ppm w
≤10 ppm w
≤0.65 ppm w
≤-65° C
≤1 ppm w
≤0.3 ppm w
≤1 ppm w
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