93
6 Maintenance
WARNING
A safety valve with a nominal opening pressure of 8.0 bar must be part of the filling device.
The safety valve prevents the pressure compartments from being overstressed due to an
impermissibly high pressure.
To fill the breaker with gas, a service unit may be used since this contains all the necessary facilities.
If a service unit is not available, a vacuum pump must then be available for evacuating the circuit-breaker prior to
the SF
6
being filled in.
The SF
6
-gas is then taken directly from a gas cylinder via the SF
6
filling device W423.
Filling by using a service unit
Connect the service unit at the filling connection W1 (Fig. 63). Evacuate the circuit-breaker down to a pressure of
< 0.02 bar; then switch the service unit for "fill". The required filling pressure and response values are
temperature-dependent and must be taken from the diagram,
SF
6
filling curve and response values of the density
monitor,
see 3.1
Technical Data.
1001304a
W1 Filling
flange
Fig. 63
Filling flange W1
Filling the breaker from the gas cylinder
Siemens offers a complete filling device of type W423 for filling the circuit-breaker with SF
6
gas from a gas
cylinder (Fig. 64).
