Silicone oil purification

Posted by John Doo on April 12th, 2018

When transformer are operated in fire hazard areas (in vicinity of welding equipment or high-current drives, the oil immersed equipment may catch fire.

Since mineral oils, most commonly used as a liquid dielectric and coolant in power transformers, are highly flammable, an alternative solution was required. 

Polychlorinated biphenyls have long been used as a non-flammable dielectric, until their toxicity was proven. Since then, most countries have decommissioned the PCB filled electrical equipment. PCBs were replaced with silicone oil purification. This material has the following characteristics:

• No color or smell;
• Water tightness;
• High dielectric strength;
• Good coating performance;
• Stability to rapid temperature changes;
• Chemical inertness (rarely reacts with other substances);
• Safety.

Silicone oil is a silicone elastomer. These liquids are formed by silicon and oxygen atomic bonds. They are resistant to high temperatures, mechanical and chemical influences.

Oxidation of Silicone Transformer Oil

The difference between silicone transformer oil and mineral or synthetic oil is the former’s chemical homogeneity. This adds to the material’s thermal resistance, which allows to heat this dielectric much higher than is normal for a loaded transformer without oversaturation with evaporating gas or corrosion.

Under the same mechanical and physical influences, regular and silicone transformer oils accumulate impurities differently. Silicone oil oxidises very slowly, and only at or above 175 ⁰C. As temperature increases, the oil polymerizes and becomes thicker. Even oxidized oil contains no sludge or acids.

Regeneration of Silicone Transformer Oil with GlobeCore Units

The CMM-2.2 mobile oil unit employes vacuum and heat to dry, filter and remove gas and water from insulating liquids used in high voltage transformers.

The unit has three modes of operation:

• Heating and filtration;
• Heat and vacuum silicone oil purification;
• Vacuum evacuation.

The unit is housed inside a container installed on a two axle trailer. The container houses a vacuum chamber, input and output oil pumps, oil heater, piping, filtes, a control cabinet, a vacuum pump and other components. The unit’s small size makes it possible to take it directly to the location of the transformer.

The СММ-2.2 works equally well to purity both mineral dielectric fluids and silicone transformer oil.  The material should comply with the following requirements before processing:

• Viscosity of 2-12  mm²/sec at 50⁰С;
• Density of 800-950 kg/m³  at 20°С;
• Moisture content below 100 ppm.
• ISO 4406 purity class above -/19/16.

It should be noted that switching from processing one oil type to another requires washing of the unit, as well as changing filters and activators in the vacuum chamber.

GlobeCore GmbH is one of the world leaders in industrial manufacturing. Products of GlobeCore are used in transformer oil purification and degassing, insulation oil filtration, power transformer vacuuming.
The head office is located in Oldenburg, Germany. Our systems have been supplied to and are successfully operated in 70 countries. A network of 17 dealers supports global sales and services.GlobeCore established representative offices in United States, and South Africa and in United Arab Emirates to extend reach and improve efficiency. We actively expand production and sales territories, develop our infrastructure and introduce new additional services. Over 260 specialists are working as a team from metal cutting to final assembly of the products.