Japan's Top Runner program sets mandatory minimum efficiency standards for power transformers — broadly comparable to the EU's Ecodesign Directive.

With the transition from Top Runner II (2014 criteria) to Top Runner III (2026 criteria) scheduled for April 2026, many manufacturers began phasing out production of 2014-standard units in late 2025. As order books closed, panel builders and system integrators still operating with legacy cubicle designs faced a sudden supply shortage.

The client — a panel builder operating across Japan — runs a make-to-order business model. Transformer specifications are only confirmed when a customer order comes in, which means buffer stock is essential to avoid delivery delays.

Two key risks emerged:

① Post-deadline supply risk
If a customer order requiring a 2014-standard transformer arrived after April 2026, the client would have no inventory to fulfill it — and no available suppliers accepting new orders.
② Cubicle incompatibility
Transformers built to the 2026 standard are physically larger due to enhanced insulation and efficiency requirements. They do not fit inside cubicles designed around the 2014 standard. Redesigning enclosures would require additional engineering time and cost.

The client contacted multiple transformer suppliers.
Everyone came back with the same answer: "We are no longer accepting orders for 2014-standard units."
However, GBP accepted.

Working closely with the client, GBP mapped the required coverage across Japan, accounting for regional frequency differences and capacity requirements.

Six customized specifications covering:

• Frequency: 50Hz (Eastern Japan) / 60Hz (Western Japan)
• Capacity: 500kVA / 300kVA
• Voltage: 440V / 420V

A total of 119 units were manufactured and delivered within two months of order confirmation.
The client secured sufficient buffer inventory ahead of the April 2026 regulatory transition.

The project demonstrates three operational capabilities critical during regulatory transitions:

• Direct manufacturer engineering support from the specification stage
• Parallel design across multiple configurations
• Maintained two-month lead times despite market constraints

GBP also provides customization of physical dimensions — including width, height, depth, terminal position, and withdrawal direction — to ensure compatibility with existing cubicle designs.

The 119-unit delivery was not just a successful project. It was a live proof-of-concept.

It demonstrated that GBP can:

• Respond to urgent, large-volume custom orders
• Maintain short lead times under market pressure
• Design across multiple specifications in parallel
• Deliver on time when the supply window is narrow

From April 2026, GBP will actively deliver Top Runner III transformer in Japan, backed by a stable and reliable supply chain for our customers.

GBP Co., Ltd. is a Tokyo-based renewable energy solutions developer specializing in the engineering, procurement, and supply of high-efficiency power transformers and high-voltage electrical equipment. We serve EPC contractors, utility-scale developers, and industrial operators across global markets—delivering reliable, high-performance solutions tailored to regional needs and international standards.

For any enquiries regarding our transformers, please feel free to contact us.