The transformer serves as the backbone of an electrical power system. This article speaks about the properties of the mineral oil in the transformer.
TRANSFORMER OIL
One of the reliability factors of an electric transformer is the transformer oil. The insulations for the transformer windings are provided by the insulating oil filled in the tank of the transformer. The heat dissipation in the transformer is absorbed by the transformer oil so that it is served as a coolant. Hence frequent testing of moisture content in the oil is very necessary for the reliability of the power system. Paraffin or Naphtha based oils are widely used as the insulating oil in a transformer.
PROPERTIES OF TRANSFORMER OIL
PROPERTIES OF TRANSFORMER OIL
- Dielectric breakdown voltage- The insulating property of an electrically insulative material can be determined by its dielectric strength (dielectric break down voltage). It is basically the voltage value that can lead to the loss of the ability to withstand electrical stress. The minimum value of dielectric breakdown voltage of a typical transformer oil is 28 kV (RMS).
- Moisture content- It basically pollutes the transformer oil by reducing its insulation level. It is generally measured in parts per million (ppm). Generally accepted moisture content of mineral oil is 35 ppm.
- Flash point - It is basically the minimum temperature that a material can ignite a fire. The flash point of the transformer oil is 140 degrees Celcius or more.
It is very essential to maintain a level of oil in the transformer tank. When the oil level gets decreased during operation, air from the atmosphere is likely to enter the tank. These air molecules may contain moisture. A silica gel breather is used remove the moisture content from these air molecules. The reliability of the transformer also depends upon its high thermal conductivity and chemical stability.
