Manual ZX0 HB 600 en - Revision 05 | 61
Fig. 4.4.2.1: Pressure gauge with operating pressure diagram
4.4 Observation of the
display and monitoring
facilities
The high voltage compartments must have a sufficient insulating
gas pressure during operation (please see the table entitled “Tech-
nical data” for the pressures, chapter 10). The density of the SF
6
insulating gas is monitored during operation by a density sensor
(temperature-compensated) or by a pressure gauge.
4.4.1 Gas monitoring with density
sensors
The gas monitoring system with density sensor is used in systems
with auxiliary power supply. If the gas pressure falls below the
level for a warning signal, a signal is issued to indicate that the
insulating gas should be topped up. In circuit-breaker systems the
signal is indicated by a warning lamp or on a panel control unit. In
switch-disconnector systems, the signal is indicated by a warning
lamp.
When a switchgear is isolated for a relatively long period, the
auxiliary power supply is to be maintained in order to monitor the
insulating gas density.
4.4.2 Gas monitoring with
pressure gauge
The gas monitoring system with pressure gauge is used in sys-
tems without auxiliary power supply. The pressure gauge is locat-
ed in the low voltage compartment of the relevant panel and can
be read even when the low voltage compartment door is closed.
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Check the insulating gas pressure at regular inter-
vals. The insulating gas pressure must be within
the limits shown on the operating pressure diagram (depend-
ent on the temperature in the low voltage compartment).
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The pressure gauge is not temperature-compen-
sated. Remember that the temperatures in the low
voltage compartment and the gas compartment are assumed
to be equal. Temperature deviations can lead to faulty
readings.
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