Situation

A global leader in the energy and infrastructure sector

Technical specifications of transformer:

Manufacturer: xxx
Year: 2012 (new)
Power [MVA]: 80
Voltage [kV]: 227/21/21
Oil mass [kg]: 26.700

Problem

Following an initial request to fill the new transformer, when the Sea Marconi technicians arrived they noticed there was free water inside the transformer.

This was due to the transformer not being properly sealed prior to transportation.

Solution

Sea Marconi carried out a rather complex operation in three separate stages:

  1. Dehydration of the papers by the direct “hot oil + vacuum” drying technique
    This phase involves applying a vacuum to the transformer tank, filling it with hot oil to cover the windings, draining the transformer rapidly and repeating the process until the established values are achieved (water < 10mg/kg; dielectric strength > 70kV; amount of water extracted < 0.25 litre/24 hours).
  2. Refilling and treatment
    This phase involves applying a vacuum to the transformer tank, filling it with oil and subsequent physical treatment of the vents

The process took just over two weeks, during which 2.85 litres of water was extracted from the oil/transformer system.

Identified Critical issues


Applied solutions

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