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NY 815901

NOV 21, 1995

CLA-2-85:S:N:109 815901


TARIFF NO.: 8542.19.0090

Mr. Dale Folgate
Honeywell Microswitch
Honeywell Inc.
11 West Spring Street
Freeport, Il 61032-4353

RE: The tariff classification of a current sensor from Scotland

Dear Mr. Folgate:

In your letter dated October 5, 1995, you requested a tariff classification ruling.

The merchandise is described in your letter as a closed-loop linear current sensor. A current sensor is an electronic device that detects or measures the amount of AC or DC current flowing through a wire and provides a digital or analog output. Sensors are used for ground fault detection, control feedback loops, motor overload detection and energy management. Closed loop current sensors are made up of a magnetic core, a secondary coil winding around the core, an analog output Hall-effect integrated circuit (IC), an operational amplifier and supporting electronics and a plastic housing. A wire carrying the to be measured current (primary) is placed through the core of the sensor. The current in the primary generates a magnetic flux field around the wire. The flux is concentrated on the Hall IC by the magnetic core. The Hall IC generates a voltage proportional to the strength of the magetic field. The operational amplifier creates a current that is passed through the secondary winding to produce a magnetic field with the opposite polarity to the field created by the primary current. Sensors work by the null balance principle which is always driving the total magnetic flux in the core to zero. The current in the secondary winding is therefore a mirror image of the primary current reduced by the number of wire turns in the secondary winding. Passing the secondary current through a precision measuring resistor gives a voltage drop proportional to the current in the primary circuit.

The applicable subheading for the current sensor will be 8542.19.0090, Harmonized Tariff Schedule of the United States (HTS), which provides for "Electronic integrated circuits and microassemblies; Monolithic integrated circuits: other: other: other: other, including mixed signal(analog/digital): other." The rate of duty will be free.

This ruling is being issued under the provisions of Section 177 of the Customs Regulations (19 C.F.R. 177).

A copy of this ruling letter should be attached to the entry documents filed at the time this merchandise is imported. If the documents have been filed without a copy, this ruling should be brought to the attention of the Customs officer handling the transaction.


Roger J. Silvestri

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