Successful Ul- certification of compact core dry type transformers in record time

VPI (Vacuum Pressure Impregnated) - triangular core transformer is a new technology introduced by SGB USA in the North American market. It is the economical choice for moderate to harsh environments and can be used indoor (NEMA 1) or outdoor (NEMA 3R) applications. Typical usage in most commercial and industrial applications.

Advancements in manufacturing techniques and the increased performance demands have paved the way for making this cutting-edge triangular wound technology possible. The symmetrical structure produces great savings and benefits in areas such as footprint, weight, reduction in sound levels, harmonic content, stray magnetic fields, improved efficiency levels, and life expectancy extension when comparing a conventional (3-legged stacked core) against a symmetrical triangular (wound core). Regarding the efficiency levels it is to be explicitly emphasized, that reductions of 20% in no-load and 5% in load losses compared to traditional technologies were confirmed.

Compact core VPI transformers can be built up to 3.000 kVA with primary voltages from 600 V – 27 kV and secondary voltages up to 1000 V with an insulation system of 220° C

Aside from setting up the unique machinery for production, preparing the designs and start the marketing process it is essential to obtain the official UL- certification.

Fabio David Flores Rodriguez, Engineering Manager at SGB-USA an 3D Core UL Project Manager reports on the qualification and certification process:
The Certification process is broken down in three stages and officially began on October 21, 2019.

Stage 1 - Documentation certification, engineering support and pre- review

This step required the submittal of a preliminary report and permanent exchange with the UL and could be concluded and approved by UL on November 7, 2019.


Stage 2 - Fabrication & certification with witnessed testing at SGB-USA Tallmadge

In order to accomplish this milestone, the full integration of engineering, procurement, production and quality departments was needed.

In an excellent team effort, we managed to release the as- built drawings and materials for production November 21, 2019. This included

  • Core and Coil
  • Accessories Fans and heaters, ETM and bus bar
  • Enclosure Nema1

Final inspection and witness testing with complete notice of competition was received on January 22, 2020.


Stage 3 - Initial Product Inspection & Engineering Documentation and Certification

On January 30, 2020 Certificate of Compliance was received and on February 2, 2020 final inspection approval was received for:

  • Compact Core - HV1 Product Type, “Electrical Insulation system”
  • Compact Core - N0 Product Type, Recognized UL - Transformer Distribution, Dry type over 600 Volts”
  • Compact Core - N1 Product Type, Listed UL - Transformer Distribution, Dry type over 600 Volts”

In summary: the full certification process could be accomplished in only 14 weeks on the very first units that were manufactured at the SGB USA Tallmadge site. This was only possible thanks to the cross- functional team effort including project management, procurement, engineering, production and quality.

SGB USA is now in full compliance to the North- American requirements and is looking forward to demonstrating the outstanding advantages of its superior technology to their customers.




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