Installation
Calculating the SF
6 gas filling pressure
For u sing th e pressure gau g e (tools)
P31--9001EN/02
2/4
01--2011
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GRID
Technical data
SF
6
gas
The following table gives the characteristics of the SF
6
gas:
Absolute pressure
at 20°C
p
re
Absolute filling pressure for insulation 0.75 MPa
For a relative pressure
at 20°C and101.3 kPa
p
re
Assigned relative filling
pressure for insulation
+0,01
-- 0
0,65 MPa
p
ae
Relative alarm pressure for
insulation
+0,02
-- 0
0,54 MPa (p
me
+0.03 MPa)
p
me
Minimum relative insulation
pressure
+0,02
-- 0
0,51 MPa
Density of SF6 gas
p
re
49.59 kg/m
3
p
ae
41.66 kg/m
3
p
me
39.55 kg/m
3
Minimum permissible temperature
up to
-- 3 0 °C
Example
Determination of the filling pressure in SF
6 gas for a circuit breaker .
Parameters Values
p
re
Assignedrelative filling
pressure for insulation
in SF
6
gas
0,65 MPa
(94.27 psi)
Ambient Temperature 5°C
Local atmospheric pressure 93,2 kPa
Filling with
SF
6
gas
The following table gives the steps for calculating the filling pressure for
SF
6
gas:
Step
Action Result
1 In the table (page 4) ”Relative
pressure values for
SF
6
gas
corrected for temperature,” read
the value p
re
situated in the
range t°C=5.
0,603 MPa
2 Calculate the atmospheric
pressure variation :
0,1013 -- 0,0932
0,0081 MPa
3 Calculate the assigned relative
pressure p
re
for 5°C:
0,603 + 0,0081
0,6111 MPa
4 The filling takes place at the
assigned pressure, increaed by
0.01 MPa so:
0,6111 + 0,01
Filling with SF
6
gas
0,621 1 MPa
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