24 June 2024

The following article on diagnostic online monitoring solutions being crucial to extending the lifespan of oil transformers and preventing costly downtime, is written by Sarika Andee, marketing leader: field service at Schneider Electric. It is part one of a two-part series.

Transformers are vital components in the fields of electrical engineering and power distribution, as they play a key role in stepping up or down voltage levels, which ensures the efficient transmission of electricity.

While the cost of a transformer can vary significantly based on numerous factors, they are typically huge investments for any operation.

Additionally, not all transformers are off-the-shelf items but are often tailored to a customer’s unique specifications, which can push up costs and manufacturing lead times.

Hence, when a transformer fails, it can result in prolonged and expensive downtime that can severely affect an entire operation – whether in a residential or industrial setting. This underscores the importance of performing regular maintenance on this equipment to mitigate risks such as coil degradation or high moisture content that can lead to failure.

Dry transformers – unlike oil transformers – do not rely on liquid to dissipate excess heat and meet temperature classification requirements and need very little in terms of maintenance. Oil transformers, on the other hand, require regular health checks and maintenance to prolong their lifespan.

Unfortunately, the traditional approach to oil transformer maintenance is reactive – when something goes wrong – and schedule-based, with an oil sample typically taken once a year to check issues such as dielectric strength, water content, acidity, sludge content and flash point.

Snapshot of current status

While a schedule-based maintenance approach can provide a snapshot of a transformer’s current status at the time, these insights are limited.

Anything can change after the sample is taken, so this approach is not effective in predicting the failure rate of a transformer or when it will fail.

More effective is a condition-based approach to maintenance, based on continuous monitoring tracks several parameters in real-time, such as humidity, partial discharge and temperature. Condition-based monitoring is done with an online digital solution connected to a probe that is installed in the transformer to continuously gather data about its condition and recommend any interventions that may be required.

Proper condition monitoring-based maintenance can prevent emergency and breakdown maintenance, as any potential risks can be identified and addressed before they become serious problems. This, in turn, can eliminate costly downtime that can have widespread and severe impacts.

Condition monitoring provides transformer owners and operators with detailed real-time analytics via a remote dashboard, enabling them to not only see an asset’s current condition but also its lifespan. For example, owners who operate a fleet of transformers at their site can receive a status summary that shows how many are in good condition, how many are at risk and whether any of them are in a critical state.

Recommended interventions

Each insight is linked to a specific condition index on a transformer, providing details about potential or existing problem areas, such as deteriorating insulation, high water content in the oil and hotspot temperature. Each alert is coupled with recommendations of what should be done in terms of maintenance.

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