The motivations for power and distribution transformer retrofilling are numerous. They range from addressing an urgent need on a single asset, to rolling out a network-wide program with clear financial returns.
Each transformer has unique operational factors that influence the situation such as load, asset design, age, location, and environment.
This is due to the unique capabilities of ester fluids and their performance in transformers, resulting in cost savings without sacrificing reliability.
Many transformer owners can financially justify ester fluid retrofills based on just one of these factors. When multiple factors are evaluated together, they create a very compelling business case for retrofilling with ester fluids.
The MIDEL family of transformer fluids comprises MIDEL eN , MIDEL eN and MIDEL . The “eN” prefix denotes natural esters, which are formulated using renewable base oils from different seed crops, whilst MIDEL is a synthetic ester fluid. All MIDEL fluids are fully/readily biodegradable. MIDEL eN is not sold in Australia.
MIDEL eN is formulated from rapeseed/canola oil and is a cost-effective general-purpose fluid. Like all natural esters, it is ideally suited to non-free-breathing distribution and power transformers. This rapeseed/canola ester is suitable for use in all climates and has superior oxidation characteristics compared to soya ester fluids.
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MIDEL natural esters meet the IEC standard.
MIDEL is specifically formulated to be a fire safe, high performance fluid providing all the benefits of ester technology in an extremely robust formulation. It is the fluid of choice when the performance demands on the transformer are higher, especially if located in a cold climate (it has a pour point of -56°C) or when there is a risk of contact with air.
In addition to being suitable and widely used for distribution and power transformers, MIDEL is also ideal for high temperature, breathing type equipment. It has a long track record in demanding applications such as wind turbines and rolling stock and is proven up to 433kV. MIDEL meets the IEC standard.
During filling and subsequent operation of the transformer, a very low moisture content in the oil is required – at just a few ppm. Oil has a natural tendency to absorb moisture from its surroundings, forcing the construction of a sealed system. Any “breather” points should be protected by filters with moisture absorbers to minimise the risk of water entering the system.
Oil transfer processes, e.g. from transport tanks to vats, should be carried out in such a way as to reduce oil gassing. Dissolved gases can affect oil performance, so it is necessary to keep them low.
Transformer manufacturers often specify that the oil temperature during filling should be higher than 50°C. In winter, maintaining this temperature requires appropriate heating systems and insulation of system components. It is also often necessary to ensure the correct ambient temperature for process support machinery, such as pumps or aggregates.
For more information, please visit Oil Transformer.