PCB

ASTM D4059

A treated solution including the sample is analyzed by gas chromatography utilizing an electron capture detector, which is sensitive to chlorine containing species. The resulting chromatogram is compared against standard chromatograms for the various known Aroclors. The results are reported in parts per million for each Aroclor or mixture of Aroclors present.

Regulations prohibiting the commercial distribution of polychlorinated biphenyls (PCBs) mandate that insulating oils be examined for PCB contamination levels to assure that new products do not contain detectable amounts.

PCB analysis is required by the laboratory for equipment that is not certified to be PCB Free.
Equipment that was installed post 1975 is usually PCB free and should have written certifications and machine labeling to that effect. If in doubt, the laboratory will run a PCB analysis on the first sample only from the equipment.

Screening Test Suite

Test Identification	Test Description	Purpose of Test
Dielectric Strength ASTM D877	Sample is placed in a test cup equipped with 1 inch diameter vertical disk electrodes spaced 0.1 inches apart. Voltage is applied to the electrodes and the test value reported in kV minutes reflects the dielectric breakdown at 60 Hz.	This test measures the ability of the oil to withstand electrical stress at power frequencies without failure. A low value for the dielectric-breakdown voltage generally serves to indicate the presence of contaminants in the oil.
Interfacial Tension ASTM D2285	Determination of the size of a water drop that is formed below the surface of the oil. The size of the water drop correlates to dynes per centimeter as a measure of force.	Determines the force to rupture the oil film at an oil/water interface. A decreasing value indicates the accumulation of contaminants and/or oxidation products that may attack the transformer insulation.
Specific Gravity ASTM D1298	Determination of the relative density by comparing the given volume of sample at a specific temperature to the mass of an equal volume of water at the same or different temperature. Value is expressed as ratio of the water constant.	Used to determine the mixibility of different oils and the potential for ice to float on the oil in cold climates that may cause flashover of the conductors.
Acid Number ASTM D664	Acid Number is determined by titration of a known substance, such as KOH, in order to determine an unknown quantity. Weighed samples are titrated using an automatic titration system.	TAN of a used oil is one measure of its degree of degradation by oxidation or contamination such as paint, varnish, or other foreign matter.
Karl Fischer ASTM D4928	This test produces iodine when electricity is conducted across a mesh screen. The electrical current needed to create iodine and remove existing water is measured and converted to parts per million (ppm).	A low water content is necessary to obtain and maintain acceptable electrical strength and low dielectric losses in insulation systems.
Color ASTM D1500	Using a standard light source, the sample is compared with colored glass disks ranging in value from 0.5 to 8.0. When an exact match is not found and the sample color falls between two standard colors, the higher of the two colors is reported.	Observations of darkening color in short periods of time is an indication of either contamination or deterioration of the oil.

Element	Purpose of Test
Hydrogen (ppm)	Key indicator of Corona. Secondary indicator of Arcing and Overheated Oil.
Methane (ppm)	Secondary indicator of Corona, Arcing, and Overheated Oil.
Ethane (ppm)	Secondary indicator of Corona and Overheated Oil.
Ethylene (ppm)	Key indicator of Overheated Oil. Secondary indicator of Corona and Arcing.
Acetylene (ppm)	Key indicator of Arcing. Secondary indicator of severely Overheated Oil
Carbon Monoxide (ppm)	Key indicator of Overheated Cellulose. Secondary indicator of Arcing if the fault involves cellulose.
Carbon Dioxide (ppm)	Secondary indicator of Overheated Cellulose. Secondary indicator of Arcing if the fault involves cellulose.
Oxygen (ppm)	Indicator of system leaks, over-pressurization, or changes in pressure or temperature.
Nitrogen (ppm)	Indicator of system leaks, over-pressurization, or changes in pressure or temperature.
Total Dissolved Combustible Gas (ppm)	The total concentration of the 6 combustible gases (H2, CH4, C2H2, C2H4, C2H6, CO) in parts per million (ppm).
Equivalent Total Combustible Gas %	The percentage of combustible gases found in the oil. This is calculated by TDCG / Total Gas x 100 (%).
Total Gas (ppm)	The total concentration of all 9 dissolved gases in parts per million (ppm).
Carbon Dioxide / Carbon Monoxide	Trending Ratio used to determine severity of cellulose degradation.
Oxygen / Nitrogen	Trending Ratio used to determine system leaks, over-pressurization, or changes in pressure or temperature

50 cc glass sample syringes will be provided by Predict for sample collection.
A minimum of 40 cc is required to run dissolved gas analysis.
Shipping costs of sample containers both ways is included in the cost per sample.

Fault Type	Key Gas(es)	Additional Gases	Notes
Thermal - Fluid	CO*, CO2, methane	H2 and ethane	-O2 must be present to form CO and CO2 -Methane favors low O2
Thermal - Cellulose	CO* and CO2	---	---
Corona	H2* and methane	CO, acetylene, ethylene, ethane	---
Arcing	H2* and acetylene	methane, ethylene, CO, CO2	-Ratio of acetylene/H2 increases with increasing arcing energy

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