Retrofit solution: Replacing Hitachi OLTC with VACUTAP® VM®

It is more than ten years ago when Japanese transformer manufacturer HITACHI decided to stop producing its own On-Load Tap-Changers (OLTC). Since then, HITACHI has relied on MR’s vacuum technology for the regulation of generation, transmission and large distribution transformers. VACUTAP® VR®, VM® and VV® are a kind of standard for new HITACHI transformers in the meantime.

However there are still a couple of Hitachi transformers in operation, which are regulated by HITACHI-made high-speed resistor type tap-changers. While the transformers are in good condition, the OLTCs are reaching the end of their life with their maximum number of switching operations. This means that the entire transformer can no longer be operated and has to be replaced. On the other hand the Japanese end-users are trying to reduce their asset management cost. They therefore welcome opportunities to extend the life of their transformers significantly.

MR’s VACUTAP® VM® is perfect for HITACHI engineers to offer a solution to their customers: replace the old HITACHI OLTC with a VACUTAP® VM® and thus continue to operate the transformer. MR's colleagues specialized in replacement and retrofitting worked out an according solution. Reinhausen Solutions Co., MR's service company in Japan as the OLTC specialist, and HITACHI as the transformer specialist, jointly convinced one of the Japanese end-users of the merits of a pilot project. Together they proved that the solution works properly and offers the customer decisive cost advantages.

Features such as MR's proven reliability and the service interval of 300,000 operating hours of MR's vacuum-based OLTC technology scored points with the customer. HITACHI as main contractor and Reinhausen Solutions Co. as subcontractor were able to carry out the first OLTC replacement at a Japanese end-user in September 2019 - to the customer's complete satisfaction.


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