Standard Test Methods for Water Vapor Content of Electrical Insulating Gases by Measurement of Dew Point

Importancia y uso:

5.1 Certain gases have excellent dielectric and electric arc interruption characteristics, making their use in electrical installations desirable.

5.2 Water content, as the test parameter, is important in determining the gas's dielectric effectiveness. Under certain conditions, water may condense and become a conducting liquid, breaking down the gas’s dielectric properties. The water content of these insulating gases, as expressed by dew point, is listed in Specifications D1933, D2472, and D3283.

5.3 Once the dew point is determined, Table 1 may be used to convert it into moisture content. Once moisture content is known, the lowest temperature at which gas-insulated equipment can be safely operated is typically determined by reviewing the equipment's specifications.

5.4 The dew point of the test gas is independent of the gas temperature but does depend on its pressure. Many moisture measurement test instruments are sensitive to pressure, and display moisture values at the instrument inlet pressure and not necessarily at the pressure of the sampled system. It is, therefore, important to account for this condition to avoid serious measurement errors.

Subcomité:

D27.07

Referida por:

D1933-03R26, D2472-15R23, D3283-98R20

Volúmen:

10.03

Número ICS:

29.040.20 (Insulating gases)

Palabras clave:

adiabatic expansion; aluminum oxide; chilled mirror; condensation; dew point; electrical insulating gas; fog; hygrometer; moisture content; SF6; silicon oxide; water vapor content ;