Static converter classification turns on essential function, with control features treated as incidental to AC-to-DC conversion.

Static converters were treated as classifiable under Heading 85.04 because their essential function was conversion of alternating current to direct current. The monitoring, protective and control features were considered incidental and subsidiary to the conversion function, and did not give the goods an independent motor-control character. On the technical evidence, the primary nature of the goods remained that of a converter, so classification under Heading 85.37 or Heading 85.43 was not warranted.

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Issues: Whether the goods in question were correctly classifiable as static converters under Heading 85.04, or whether their additional control features required classification under Heading 85.37 or Heading 85.43.

Analysis: The goods were found to perform the essential function of conversion from alternating current to direct current. Their monitoring and protective features were held to be incidental to, and not independent of, the conversion function. The presence of control elements did not change the primary character of the goods, and the technical evidence supported the finding that the motor-control aspects were subsidiary to the converter function.

Conclusion: The goods were correctly classified under Heading 85.04, and classification under Heading 85.37 or Heading 85.43 was not warranted.

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