These systems indicate the current SF6 density levels in each individual gas zone.
The different types of gas monitoring:
- Temperature compensated pressure gauge or switch with alarm contacts
- Pressure gauge with separate density switches
- Pressure transducer with separate temperature compensation
- Density transducer independent of temperature and pressure
- Pressure and temperature transducer with separate density calculation
Each gas zone should be furnished with a gas density monitoring device capable of signaling a minimum of
two independent alarms. Each device should have electrically independent contacts that operate at the
alarm levels. The low-gas density alarm, which is nominally 5% to 10 % below nominal fill density, should send a signal to the local user’s remote system.
Typical information that can be extracted from gas monitoring:
- Display of leakage rate in percent per year
- Time in days until first low gas alarm stage will be reached
- Time in days until the minimum functional density alarm stage will be reached
Pic show gas density monitor mounted on the GIS enclosure. This type displays temperature compensated
pressure with a simple to read dial and with color codes