Dew point test
Note: As per TCS-P-105 REV.01 Criteria for CB/Other gas
section: less then-35˚C
SF6 is often used as a dielectric and arc-suppression medium in gas
insulated equipment (GIE). Most manufacturers of GIE’s recommend maximum and
minimum tolerances for certain variables within the gas, including moisture,
gas decomposition, and purity of SF6.
Exceeding the GIE recommended moisture levels
will cause formation of acidic by-products, such as HF, SO2, SOF2, etc.
Therefore, it is important that end-users measure the SF6 moisture content with
reliable, cost-effective, and durable moisture analyzers.
All test equipment requires that the sample gas
be dissipated. Thus, the longer the equipment takes to perform an accurate
reading, the more valuable gas is wasted; in addition SF6 gas is detrimental to
the earth’s ozone layer. The gas can be recaptured at the exhaust port of some
equipment.
Moisture analyzers for GIE’s should be able to
address all of the concerns, of measuring in corrosive environments, wide
temperature fluctuations, within the pressures found on different GIE’s and SF6
bottles, minimize gas waste by rapid accurate measurement.
IEEE 1125-1993 “IEEE Guide for Moisture
Measurement and Control in SF6 Gas-Insulated Equipment” is a good starting
point in assessing the moisture analyzer requirements.
