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Workshop Repairs for Medium and Large Power Transformers

Few transformers fail due to old age per se, but rather as a consequence of external faults, short circuit faults, insulation failure (dielectric failure), local overheating (causing gassing), or accessory failure (e.g., bushings, tap changers, coolers, surge-arresters).

Repairing a transformer instead of replacing it can substantially reduce investment costs and provide a faster turnaround than buying a new transformer. In repairing old transformers where the manufacturer may no longer be in existence and/or the design is obsolete and a like-for-like new replacement cannot be obtained, there may be significant savings in infrastructure costs and civil works in using the existing tank and design.

Workshop repairs for Medium and Large Power Transformers

Scope of work

Upon receipt of the transformer in the factory, a visual inspection and electrical control will be performed to provide the root cause of the failure, what rehabilitation actions will be taken, and the delivery date.

Pending the root cause and agreed actions taken, the core and coil or active part will be untanked, inspected, and partial or full manufacturing of coils will be initiated.

Following the upgrade or service of noble parts, accessories, and other auxiliary equipment, the active part is dried and replaced in the tank, refilled with fresh oil, and a high-voltage test is performed.

After the factory acceptance test, the newly revitalized transformer is ready to be delivered back to its owner.

If requested, Hitachi Energy can, of course, cater for the transport of the unit back and forth from the site.

Workshop Repairs for Distribution and Small Power Transformers

Hitachi Energy offers workshop repairs for distribution and power transformers ranging from 315 kVA to 5 MVA.

Workshop Repairs for Traction Transformers

Hitachi Energy offers workshop repairs for traction transformers to prevent unpredicted failure and ensure a long transformer life.

Transformer Refurbishment

Hitachi Energy offers refurbishment services to cover transformer rehabilitation and sustainable life extension to advance a sustainable energy future for all.

On-site Repairs

Hitachi Energy offers on-site repairs to bring the transformer factory setup to the work site with the TrafoSiteRepair™ service that is executed to the same high-quality standard as a workshop repair.

Transformer Component Upgrades

Transformers component upgrades are based on Hitachi Energy's decade-long experience in manufacturing and maintaining its products.


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Transformer service

Aging assets, rising energy demand, and the critical need to avoid unplanned outages are challenging worldwide utilities and industrials. The service portfolio of Hitachi Energy allows utilities and industrials to maximize the return on transformer assets by ensuring high reliability, reducing life cycle costs, and ensuring optimized performance while lowering environmental impact.
Hitachi Energy Power Transformers


Hitachi Energy offers distribution and power transformers, Dry-type and EconiQ™ Transformers as well as services, for industrial and commercial applications.