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Standard Test Methods for Water Vapor Content of Electrical Insulating Gases by Measurement of Dew Point
NORMA vydaná dňa 1.1.2017
Označenie normy: ASTM D2029-97(2017)
Dátum vydania normy: 1.1.2017
Kód tovaru: NS-674326
Počet strán: 6
Približná hmotnosť: 18 g (0.04 libier)
Krajina: Americká technická norma
Kategória: Technické normy ASTM
Keywords:
adiabatic expansion, aluminum oxide, chilled mirror, condensation, dew point, electrical insulating gas, fog, hygrometer, moisture content, SF6, silicon oxide, water vapor content ,, ICS Number Code 29.040.20 (Insulating gases)
Significance and Use | ||||||
5.1 Certain gases have excellent dielectric and electric arc interruption characteristics which make their use in electrical installations very desirable. 5.2 Water content, as the test parameter, is of great importance in determining the dielectric effectiveness of the gas. Under certain conditions, water may condense and become a conducting liquid resulting in a catastrophic dielectric breakdown of the insulation. 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, a conversion to moisture content may be performed using Table 1. Once moisture content is known, the lowest temperature at which gas insulated equipment can be safely operated can usually be determined by reviewing manufacturers' specifications for the equipment. 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 system being
sampled. It is therefore important to account for this condition to
avoid serious measurement errors.
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1. Scope | ||||||
1.1 These test methods describe the determination of the water vapor content of electrical insulating gases by direct or indirect measurement of the dew point and the calculation of the water vapor content. 1.2 The following four test methods are provided: 1.2.1 Method A describes the automatic chilled mirror method for measurement of dew point as low as − 73°C (−99°F). 1.2.2 Method B describes the manual chilled mirror or dew cup method for measurement of dew point as low as − 73°C (−99°F). 1.2.3 Method C describes the adiabatic expansion method for measurement of dew point as low as − 62°C (−80°F). 1.2.4 Method D describes the capacitance method for measurement of dew point as low as − 110°C (−166°F). 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific warnings, see 8.1.1, 9.2, 10.1.2 and 10.2.5. |
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2. Referenced Documents | ||||||
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