ASTM D7150 for Determination of Gassing Characteristics of Insulating Liquids
ASTM D7150 Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress at Low Temperature
1. Scope
1.1 This test method describes the procedures to determine the low temperature (120°C) gassing characteristics of insulating liquids specifically and without the influence of other electrical apparatus materials or electrical stresses. This test method was primarily designed for insulating mineral oil. It can be applied to other insulating liquids in which dissolved gas-in-oil analysis (Test Method D3612) is commonly performed.
1.2 This test method is particularly suited for detection of the phenomenon sometimes known as "stray gassing" and is also referred to in CIGRE TF11 B39.
1.3 This test method is performed on transformer insulating liquids to determine the propensity of the oil to produce certain gases such as hydrogen and hydrocarbons at low temperatures.
1.4 This test method details two procedures.
1.5 Method A describes the procedure for determining the gassing characteristics of a new, unused insulating liquid, as received, at 120°C for 164 h.
1.6 Method B describes the procedure for processing the insulating liquid through an attapulgite clay column to remove organic contaminants and other reactive groups that may influence the gassing behavior of an insulating liquid, which is suspected of being contaminated. This procedure applies to both new and used insulating liquids.
1.7 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 to determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D1933 Specification for Nitrogen Gas as an Electrical Insulating Material
D3612 Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography
D3613 Practice for Sampling Insulating Liquids for Gas Analysis and Determination of Water Content (Withdrawn 2007)
2.2 IEEE Document:
C 57.104 IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers, 1991
2.3 IEC Documents:
IEC 60599 Mineral oil-impregnated electrical equipment in service - Guide to the interpretation of dissolved and free gases analysis, 1999
IEC 61464 Guide for the interpretation of dissolved gas analysis (DGA) in bushings where oil is the impregnating medium of the main insulation (generally paper), 1998
CIGRE TF11 B39 Gas formation tendency test for mineral transformer oils, 2002.
3. Terminology
3.1 Definitions:
3.1.1 stray gassing, n - the production of gases in an insulating liquid due to heating, contamination or in combination.
3.1.2 attapulgite clay, n - also termed Fullers Earth. Highly adsorbent clay-like substance consisting mainly of hydrated aluminum silicates.
