1.3.2 Checking and Refilling of SF Gas
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Checking and refilling can be done with the front plate fixed. Refilling not be carried
out with the breaker in service position. The gas pressure should be between 3 and
0
3.5 bar absolute, in other words 2 and 2.5 bar over pressure at 20 C. Lower currents
than 25kA can still be in broken at lower pressure. Rated current can be interrupters at
atmospheric pressure provided that there is SF gas in the breaker pole, which is
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certainly valid if there is little over pressure.
0
At temperature other than 20 C of the gas the pressure (abs.) must be according to
the table below.
Pressure at Corresponding pressure in bars at various temperatures
0
20 C abs.
0 0000
Bar 0 C 10 C 20 C 30 C 40 C
0.5 0.47 0.48 0.50 0.52 0.54
1.0 0.93 0.97 1.00 1.03 1.06
1.5 1.40 1.45 1.50 1.55 1.60
2.0 1.36 1.93 2.00 2.07 2.14
2.5 2.33 2.41 2.50 2.59 2.68
3.0 2.80 2.90 3.00 3.10 3.20
3.5 3.26 3.42 3.50 3.62 3.74
The HPA breaker can be fitted with a density gauge with an alarm contact and
indicator. The green area of the indicator shows the correct pressure, the yellow area
indicates enough pressure for breaking, and when the indicator shows red the pole
has to be refilled with SF gas. If the breaker is not supplied with density gauge the
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pressure is measured manually with a special instrument. The measurements should
take place at three intervals. The HPA circuit breaker can also be fitted with pressure
switches.
Checking and refilling of SF gas is carried out according to the following instruction.
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Equipment according to fig. 16 is needed.
(14)
Fig - 8
Connection for filling of Breaker with SF gas
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