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HQ 953463

September 28, 1993

CLA-2 CO:R:C:M 953463 DWS


TARIFF NO.: 8471.99.32

Mr. Stephen S. Spraitzar
George R. Tuttle, P.C.
Three Embarcadero Center, Suite 1160
San Francisco, CA 94111

RE: DC/DC Power Supplies for ADP Machines; Static Converters; 85.04(II) and 84.71(D); Chapter 84, Note 5(B); HQ's 087907, 083956, 087050, and 086513; NY 851581; 8504.40.00

Dear Mr. Spraitzar:

This is in response to your letters of January 8 and April 8, 1993, on behalf of Computer Products, Inc., to the Regional Commissioner of Customs, New York, concerning the classification of DC/DC power supplies under the Harmonized Tariff Schedule of the United States (HTSUS). Your letters and sample have been referred to this office for a response.


The merchandise consists of DC/DC power supplies (model no. WR24T05-12/55K) specifically designed for computer applications and physical incorporation into automatic data processing (ADP) machines. The principal function of the power supply is to supply to an ADP system a voltage which is highly stabilized and regulated. This is accomplished in the following manner: the DC voltage is chopped into a high frequency pulse by the switching transistor. The switching pulse is then fed into the transformer, and is thereafter transformed into a pulsed voltage just above the level of the desired output voltage. The resulting internal rectification of the pulse output voltage is converted to a rough DC voltage by rectifiers. The output voltage is then filtered by an inductor and a capacitor, and the end-result is a smooth and steady voltage, usually 5 or 12 volts.

The power supply also possesses mechanisms for the functions of transient suppression of electromagnetic transmissions, current overload protection, energy storage, over-voltage detection, and over-current protection, remote sensing, remote on-off, voltage adjustment.

The subheadings under consideration are as follows:

8504.40.00: [s]tatic converters.

The general, column one rate of duty is 3 percent ad valorem.

8471.99.32: [a]utomatic data processing machines and units thereof . . .: [o]ther: [o]ther: [p]ower supplies: [u]nits suitable for physical incorporation into automatic data processing machines or units thereof.

Goods classifiable under this provision receive duty-free treatment.


Whether the DC/DC power supplies are classifiable under subheading 8504.40.00, HTSUS, as static converters, or under subheading 8471.99.32, HTSUS, as power supplies.


Classification of merchandise under the HTSUS is in accordance with the General Rules of Interpretation (GRI's), taken in order. GRI 1 provides that classification is determined according to the terms of the headings and any relative section or chapter notes.

In understanding the language of the HTSUS, the Harmonized Commodity Description and Coding System Explanatory Notes may be utilized. The Explanatory Notes, although not dispositive, are to be used to determine the proper interpretation of the HTSUS. 54 Fed. Reg. 35127, 35128 (August 23, 1989). In part, Explanatory Note 85.04(II) (pp. 1338, 1339) states:


The apparatus of this group are used to convert electrical energy in order to adapt it for further use. They incorporate converting elements (e.g., valves) of different types. They may also incorporate various auxiliary devices (e.g., transformers, induction coils, resistors, command regulators, etc.). Their operation is based on the principle that the converting elements act alternately as conductors and non- conductors. . .

This group includes:

(D) Direct current converters by which direct current is converted to a different voltage. . .

This heading also includes stabilised suppliers (rectifiers combined with a regulator), except those specifically designed to form a unit of heading 84.71.

In part, Explanatory Note 84.71(D) (pp. 1299, 1300) states:


This heading also covers separately presented constituent units of data processing systems. Constituent units are those defined in Parts (A) and (B) above as being parts of a complete system.

Apart from central processing units and input and output units, examples of such units include:

(6) Power supply units, whose main function is to supply continuously, under the control of the system to which they belong, the appropriate stabilised power level in response to the requirements of the various units making up the system.

Chapter 84, note 5(B), HTSUS, states that:

(B) Automatic data processing machines may be in the form of systems consisting of a variable number of separately housed units. A unit is to be regarded as being a part of the complete system if it meets all of the following conditions:

(a) It is connectable to the central processing unit either directly or through one or more other units; and

(b) It is specifically designed as part of such a system (it must, in particular, unless it is a power supply unit, be able to accept or deliver data in a form (code or signals) which can be used by the system.

We agree that the power supply does in part operate as a static converter. However, it is our position that with the ability of the power supply to perform other functions, it is not described under heading 8504, HTSUS. Therefore, we find that the merchandise is not classifiable under subheading 8504.40.00, HTSUS. Also, even if the DC/DC power supply was described under heading 8504, HTSUS, Explanatory Note 85.04 precludes its classification in that provision because it is our position that it is specifically designed to form a unit of heading 8471, HTSUS.

In HQ 087907, dated July 26, 1991, a power supply unit similar to the subject merchandise was held to be classifiable under heading 8471, HTSUS. The unit performed the various functions of transforming higher voltage into lower voltage, controlling electrical noise, storing power in the event of a power disruption, causing the computer to store data, and shutting the power supply down in the event of a malfunction. See also NY 851581, dated April 28, 1990, HQ 083956, dated April 12, 1989, and HQ 087050, dated August 21, 1990.

It is our position that the power supply meets the terms of heading 8741, HTSUS, and Explanatory Note 87.41. First the power supply is a unit of an ADP machine. In HQ 086513, dated March 2, 1990, it was stated that:

[l]egal Note 5(B) denotes that power supplies are units of ADP machines even though they do not accept or deliver code or signals to the system, and that power supplies, entered separately are to be classified in heading 8471 (which provides for units) . . .

Therefore, classification of power supplies for ADP machines appropriate under subheading 8471.99.30, HTSUSA, which unequivocally provides for ADP power supplies. (emphasis supplied).

Therefore, power supplies for ADP machines are units of ADP machines and are specifically classifiable under heading 8471, HTSUS.

Second, the subject power supply meets the definition of power supply units in Explanatory Note 84.71. It is our position that the power supply supplies continuously under the control of the ADP system to which it belongs, the appropriate power level in response to the requirements of the units making up the ADP system. For example, an ADP system exerts control over the power supply by causing it, in response to an increased power demand (i.e. uploading a computer program from the disk drive), to supply the appropriate power level (current) in response to the requirements of the system.

Consequently, we find that the power supply is classifiable under subheading 8471.99.32, HTSUS.


The DC/DC power supply is classifiable under subheading 8471.99.32, HTSUS, as power supplies.


John Durant, Director

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