UNITED KINGDOM — MIDEL’s ester-based insulating fluid has been chosen for retrofilling five 800 kVA transformers at a historic London building, following a change in fire protection regulations.

A landmark building in central London next to the River Thames had been fitted with five 800 kVA transformers in earlier decades, with mineral oil as the insulating liquid.

Due to regulatory changes over the years, the installation no longer complied with BS EN 61936-1:2010, both in terms of fire protection and the need for containment.

The lack of space needed to install fire suppression systems and the impossibility of demolishing walls to gain more clearance required an alternative insulating solution.

The customer opted to upgrade the mineral oil transformers by retrofilling them with an ester-based K-Class insulating fluid manufactured by MIDEL.

MIDEL Service Partner Eden Transformer Oil, a company specializing in on-site oil purification and replacement, was brought in to perform the retrofilling process. Each transformer was retrofilled on site during one weekend day per transformer, MIDEL said in a press release.

The transformer retrofilling process required dedicated equipment and includes allowing time to remove excess oil, heating the ester fluid to 60-80°C, further cycles of purification via vacuum dehydration plant and the addition of new gaskets.

Source: MIDEL