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Proper Load and/or On-Load Tap-Changer (LTC / OLTC) maintenance has become increasingly complex, even for the best utility and industrial managers. Factors resulting from interconnections and power networks to aging equipment and the declining pool of technical experts add to the challenge.

Tap-changers are very important components in transformers and the power grid. As they are of mechanical construction, they cause concern due to their maintenance needs and their failure probability. It is, therefore, important to ensure the integrity of tap-changers as cost-effectively and reliably as possible. Moreover, reports from international studies made by, for example, CIGRE show that faults associated with tap-changers are the origin of up to one-third of the transformer failures in service.

When you evaluate the liability of a single tap changer failure at today’s costs, establishing an effective maintenance strategy becomes a matter no one can ignore. Hitachi Energy offers a comprehensive and systematic approach to effectively maintain many manufacturers’ tap changers, including ABB, Westinghouse, Reinhausen, Moloney, GE, National Industri, and others. Our tap changer program can supplement existing in-house programs or work independently to satisfy the total maintenance need. The Hitachi Energy tap-changer team provides support 24/7, and all field services are furnished by Hitachi Energy's qualified technicians and engineers.

For services ranging from documentation and design engineering to the latest in testing and oil processing to providing 100 percent OEM grade parts and life extension kits, Hitachi Energy is the best resource for all tap changer service requirements.

Our tap-changer services increase transformer life and reliability and lower maintenance and operating costs. In order to further assist our customers, Hitachi Energy offers a wide range of monitoring and diagnostic tools, from the simple way to monitor the temperature difference between the LTC/OLTC and the transformer main tank to the most advanced solutions on the market, for example, CoreTec™. This will allow a more refined diagnosis of LTC/OLTC problems to predict maintenance/overhaul needs based on actual conditions and not on the number of switching operations.

In order to further lower maintenance and operating costs, Hitachi Energy has introduced a plug-and-play concept. This means the possibility of upgrading an old oil-breaking tap changer's type UCG and UCL to vacuum technology. A work that is as easy as normal maintenance.

Tap-changer Overhaul and Upgrade for Hitachi Energy's Transformer Sevice

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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Hitachi Energy offers repair of high-voltage condenser bushings that includes installation, preventive maintenance, condition assessment, and replacement or upgrades.

Cooling System Overhaul and Upgrades

Hitachi Energy offers one-to-one replacements and upgrades of existing cooling solutions from original size to large size transformers.


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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.