BK-130
10-2
CHECKING OIL PURITY
4. Oil Specifications
Transformer oil is a high quality insulating oil specially refined and formulated to meet the exacting
requirements of major electrical equipment manufacturers and users. It also meets Federal Specification VV-I-
530a.
High quality mineral-based transformer oil is recommended as the insulating and cooling medium for oil-
immersed transformers. It is also recommended for arc-forming apparatus such as switches, circuit breakers,
tap changers, reclosers, and fuses. General Characteristics of transformer oil include:
a. High Dielectric Strength:
Transformer Oil has high electrical insulating values as shown by their dielectric strengths of over 30,000 volts.
b. Excellent Oxidation Stability:
Excellent oxidation stability and high resistance to sludging provide protection, particularly where high
temperatures are likely to be encountered. These products are specially refined to ensure long time service
with a minimum of maintenance.
c. Freedom From Contaminants:
Absence of organic acids, corrosive sulfur, and other foreign materials, which might affect metals or insulation,
ensures long life for the oil as well as the electrical units.
d. High Interfacial Tension:
High interfacial tension shows the absence of soluble polar contaminants. Refinery sealed containers assure
maintenance of purity in transit.
e. Good Heat Transfer Properties:
Good circulation and rapid transfer of heat from the coils to the cooling fins are assured by low viscosities at all
operating temperatures.
