Maintenance keeps power transformers working for years

GEORGE NEWS - The power transformers at various George municipal substations recently underwent extensive maintenance and refurbishment to guarantee long-term life expectancy.

Mayor Leon van Wyk said this work illustrates the importance of preventative measures and making sure that key infrastructure is well maintained.

"We've started with the critical infrastructure to ensure we do whatever we can to prevent power failures. Our citizens might have noted major equipment failures taking place in other cities around the country; the maintenance done was precisely to make sure we not only prevent such occurrences in George but also prolong the working lives of our major equipment," said Van Wyk.

Director of Electrotechnical Services Bongani Mandla requested additional funding in the adjustment budget earlier this year to undertake and finish these preventative measures. Mandla said it is a key objective that we ensure that our infrastructure is well maintained to ensure that citizens are not inconvenienced.

Van Wyk congratulated the teams on a job well done and said he is very impressed with the enthusiasm and dedication of the teams who do maintenance and deal with ongoing repairs, especially during recent winds and rain storms.

Delivery time

Power transformers are manufactured on request and delivery time for new units or critical spares sometimes exceed 12 months, therefore unintended failures result in sustained power outages to communities and suburbs.

The average distribution power transformer costs between R7- and R12-million, excluding consequential damages to commercial or residential consumers. It is therefore very important that all high-value, long lead-time assets are properly maintained, and to ensure that future operational and capital costs are budgeted for the total life of the asset.

A condition-based assessment was performed to determine the useful life of all power transformers, through a contractor appointed by the municipality.

The condition-based assessments consisted of five phases:

Phase 1 (April 2021) - a non-intrusive assessment consisting of oil sampling and visual inspections
Phase 2,( May to July 2021) - an intrusive inspection consisting of an insulation test, low voltage and high voltage testing by IEC standards and procedures
Phase 3 (August 2021) - a verification and quality assurance was done and signed off by an independent specialist company in Germany
Phase 4 (November 2021) - consisted of a stakeholder engagement between the contractor and municipal officials. The report findings were presented to engineering personnel and units were prioritised, based on risk and on projections of the approximate costs of operational and capital expenditure in the next 10 to 15 years.
Phase 5 (started February 2022 after the adjustment budget) - all high-risk transformers were scheduled for maintenance and all defects were repaired, including tap changer maintenance, anti-corrosion treatment, oil filtration and the installation of maintenance-free rejuvenating air purification units.

All high priority works were completed by June this year, costing approximately R2,5m. The remaining medium and low-risk units are scheduled for refurbishment during the remainder of the 2022 to 2024 financial years.

From left are Cuan Edick (senior superintendent for substations at Electrotechnical Services); Jacques Lawrence (senior manager for substations at Electrotechnical Services); Mayor Leon van Wyk; and Letsema Ndlovo (specialised electrician for high voltage at Electrotechnical Services) at the Heather Park substation that was newly refurbished against corrosion.