Page 56 - Energize August 2022

TECHNICAL

transformer is subject to mechanical shock or there is a through-
fault on the system, this transformer has a higher risk of failing.
It should be noted that aggressive oil reconditioning when the
mechanical strength of the paper is so low can do more harm than
good.
It is strongly advised that exposure to fault risk should be
managed carefully and plans for end of life developed.

Note: Oil reconditioning can remove the evidence of paper
degradation but the degradation itself is irreversible. Figure 7: Chemical analysis graph

Review of maintenance history The assumed average maintenance cost for this transformer
The transformer had undergone oil purification on ten occasions was R 25 000 since 1995 with no benefits i.e., there had been no
since 1995 in an attempt to remove moisture and improve the improvement in fluid insulation condition with a deterioration in
dielectric, with oil replacement on 12-03-2000. The oil purification solid (paper) condition.
had no effect in improving the oil condition.
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Accessing the state of the paper insulation is vitally important
when considering a maintenance plan for a transformer. In this Contact Oilwatch, Phone 087 238-2188,
case a more cost-effective maintenance plan would be to remove support@oilwatch.co.za, www.oilwatch.co.za
the transformer to a works facility for refurbishment. Or Ian Gray, Phone 082 458-5826, ian@oilwatch.co.za

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