90
When measuring, the temperature dependence of the pressure as shown in the diagram
SF
6
filling curve and
operating values of density monitor
(see 3.1.6
Arc Quenching Medium SF
6
)
should be taken into account.
This means that, if possible, the mean temperature of the SF
6
gas in the circuit-breaker should be determined
(Measurements should be avoided in times of strong fluctuations of the ambient temperature and immediately
after high-current loads).
If the measured value falls below the specified SF
6
filling curve, correct the SF
6
gas filling (using a gas cylinder or
service unit).
Check humidity and the air content of the SF
6
-gas that may be left in the service unit (see 6.4.13
Measuring the
SF
6
Gas Humidity Content).
If the measured SF
6
pressure lies below the filling curve by not more than 0.30 bar (permissible gas loss), refill
with SF
6
.
If the measured value is more than 0.30 bar below the filling curve specified, a leak test must be carried out and
the leak must be repaired. Then the filling must be corrected.
6.4.2
Drawing Off the SF
6
Gas
It is recommended to draw off the SF
6
-gas with a service unit so that it can again be used almost completely for
the subsequent filling. The service unit has all the facilities for drawing off and filling the SF
6
-gas.
The condition of the SF
6
-gas in the service unit should be checked in advance.
6.4.3
Check of Contact System
The interrupter unit is described in section 3.4
Interrupter Unit.
)
Note
For the contact system check it is necessary to call in Siemens personal.
6.4.3.1
Dimensional Check on the Contact System
The inspection of the contact system has to be made by a dimensional and a visual check.
The permissible contact erosion will be given by the dimension a.
22.11.17 Piston
22.17.1 Pull
rod
22.17.2 Coupling
rod
22.23 Base
22.9 Pin
Fig. 60 Inspection of contact carrier
