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About the Company

Custom Transformers

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Panels & Harnesses

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Standard Transformers

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The History

Toroid Corporation (TCM) is a privately held corporation, founded in 1982. Gunnar Ennerfelt, its president and owner, holds an MSEE degree from the Royal Institute of Technology in Stockholm. Prior to immigrating from Sweden in 1982, Gunnar Ennerfelt had founded Toroid Transformator AB (TTAB) in Vaxjo, Sweden in 1978, preceded by five years as the president of Transductor AB, a company that pioneered the development of labor saving manufacturing methods of power toroids in the late sixties. In 2006, Gunnar retired from daily operations at Toroid Corporation and was succeeded by his daughter, Katarina Ennerfelt.

Company Highlights

1983 First production run shipped out in early January.





To better serve its customer base, software programs were developed to calculate transformer data based on customers' DC data after rectification. With these programs, the first prototype is guaranteed to meet the customer's specifications.



 Toroidal DC filter chokes for 60Hz were introduced to offer a better solution to using large filter capacitors for applications with high voltage requirements.




A satellite plant was opened in Salisbury, MD adding 6,000 sq.ft. to the existing 10,000 sq.ft. in Bowie, MD. All long runs were made at the new plant.




In December, the manufacturing operation in Bowie, MD was transferred to Salisbury, MD.




In April, the Bowie plant was closed and the sales and administration were relocated to the Salisbury plant.




Several new standard design product lines were introduced, including Isolation transformers for commercial and medical equipment, expansion of the line of Rectifier Transformers for 115/230V, 50-60Hz operation. A family CSA certification was obtained





The ground breaking ceremony of a new 20,000 sq.ft. plant was held in July. The actual move took place in December. The line of medical grade standard isolation transformers was expanded to include 100VA to 5000VA. Additional mounting hardware options were introduced.




In April, a new line of standard design aluminum encased hospital grade isolation transformers was introduced.




New international isolation transformers with CE marking and IEC320 outlets were introduced.




M-Series international isolation transformers with CE marking and 100V input were introduced.




New line of over 5,000 different Control Panel transformers were introduced.

Formed a partnership with a facility in China.




Katarina Ennerfelt takes over as CEO/President after Gunnar Ennerfelt retires from daily operations.





Toroid Corporation celebrated its 30th anniversary of manufacturing transformers in the United States.



2014 Officially changed name from Toroid Corporation of Maryland to Toroid Corporation.