Oil Quality Tests

Are The Key To Preventative Maintenance

Know When Maintenance Is Needed... And When It Is Not

Water, dirt deterioration from oxidation and sludge all contribute to the breakdown of transformer oil protection.  Because cooling capacity of your transformer depends on the oil, its quality must be maintained.  That means evaluating it regularly and reconditioning the oil when necessary.

To avoid expensive and unnecessary maintenance, the testing must be performed quickly and accurately.  PDC Laboratories  maintains rigorously controlled laboratory conditions, along with specially trained and experienced chemists, to assure the accuracy of your oil tests.

Neutralization Number
(ASTM D-974)

This test is important for determining the amount of acidic or basic constituents resulting from additives or degradation.  It is used as an indication of the oil's propensity to form sludge which is the result of oxidation of various transformer components.  Sludge diminishes the dielectric strength of the oil, and hinders the oil's ability to circulate through cooling ducts.

Color 
(ASTM D-1500)

Color changes predictably and measurably with the general deterioration of oil.  The darker the oil is, the more deterioration there is.  Although this test is not specific, it is a valuable indicator, especially when used with more specific tests.

Dielectric 
(ASTM D-877)

Dielectric tests measure oil's ability to withstand electrical stress without breaking down.  With the ability to withstand stress within reasonable limits, transformers are vulnerable to rapid destruction.

Specific Gravity

This is used to identify oil and can be used as a measure of gross contamination.

Water 
(ASTM D-1533)

Detects soluble in oil.  soluble water strongly affects the electrical insulating characteristics of oil.  Levels of soluble water as little as 35 ppm can diminish dielectrics strength enough to require maintenance.

Interfacial Tension (ASTM D-971)

Indicates the level of deterioration due to sludging and contamination, and monitors gradual deterioration of oil over time.

Visual 
(ASTM D-1524)

Detects solid and liquid insoluble contaminants not indicated by other tests.

Power Factor 
(ASTM D-924)

Detects the power lost when an insulating  liquid is subjected to an AC field.  It is performed to determine the quality of new or used transformer oil.  The test is sensitive to ionic contaminants such as water or oxidation by-products.

Other Tests:

VDE Dielectric (ASTM D-1816)
Flashpoint (ASTM D-92)
DBPC (ASTM D-1473)
Corrosive Sulfur (ASTM D-1275)