Oil Immersed Transformer

A: An oil immersed transformer, also known as an oil filled transformer, is a type of electrical transformer that uses oil as both a cooling and insulating medium. The transformer’s core and windings are submerged in a sealed tank filled with insulating oil, which serves two critical purposes: dissipating heat generated during operation and providing electrical insulation to prevent short circuits.

A: The working principle of oil-immersed transformer is based on electromagnetic induction and transformer principles. When AC current from the input power supply passes through the main winding, the resulting magnetic field creates magnetic flux in the iron core. This flux passes through the adjacent secondary winding, causing another voltage to be induced in the secondary winding.

A: It is recommended that the drums be stored horizontally, with bungs in 3'0 clock and 9'0 clock position, such that bungs are always immersed in oil. It is not advisable to store half filled drums for longer periods due to risk of moisture contamination from air humidity, rain etc.

A: In lieu of a fire wall, physical separation is recommended anywhere from 5 to 25 ft (1.5 to 15 m) based on the oil capacity of the transformer.

A: Containment systems are necessary to catch any oil that escapes from a transformer. Smaller installations with limited space could benefit from a compact pan, while large volumes of oil require a complete containment system solution.

A: Transformer oil's primary functions are to insulate and cool a transformer. It must therefore have high dielectric strength, thermal conductivity, and chemical stability, and must keep these properties when held at high temperatures for extended periods.

A: Check the transformer temperature and oil level indicators. Inspect all cables, bolts, and hardware for tightness. Tighten anything that may be loose. Re-energize the transformer before performing tests and analyses like breakdown voltage testing or infrared temperature analysis.

A: Overheating: Caused by overload, poor cooling, or contamination of transformer oil. Can be diagnosed by monitoring the oil temperature and performing thermal imaging inspections.
Insulation Breakdown: Resulting from contamination, moisture, or high temperatures, leading to short circuits or transformer failure. Diagnose by measuring the dielectric strength of the oil and performing DGA.
Oil Leakage: Oil leaks can be caused by seal or gasket failure. Inspected visually and through monitoring oil levels.
Partial Discharge: Caused by local electrical discharge between conductors and grounded parts. Can be detected through regular DGA and through using partial discharge monitoring techniques.