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Hall Effect sensors shrink in size and price

01 April, 2002

Hall Effect sensors shrink in size and price

Following its recent acquisition of the Japanese Hall Effect specialist NANA Electronics, LEM has released a new generation of current transducers which are smaller and cheaper than previous Hall Effect devices and have other advantages. The HX transducers are said to have a 3µs response time, a linearity of ±1% and a clearance distance of more than 5.5mm.

The traditional methods of measuring small currents were to use resistive shunts or current transformers, both of which had limitations - a lack of galvanic isolation in the case of the former, and limited bandwidth for the latter. Both also require considerable calibration effort.

LEM introduced its first Hall Effect transducers to overcome some of these limitations about three decades ago. Since then it has sold more than one hundred million of the devices. But the size and cost of the Hall Effect sensors have deterred some potential users.

The company has therefore combined the expertise of its European and Japanese researchers to develop a re-engineered family of sensors based on TATA`s SY series. The resulting sensors, which come in ratings from 3-20A, weigh a mere 8g and occupy a mounting area of just 15mm by 19mm.

Potential applications for the new sensors include:

•. DC-side current protection and motor control in frequency inverters;

• Phase current control in AC/DC servo drives; and

• Current control and short-circuit protection in industrial equipment.

The range includes special versions with two primary windings that can be connected in series or parallel, allowing just two transducers to measure all three phases in inverter applications.

The sensors have been designed to provide noise immunity without compromising bandwidth. This is expected to be particularly useful when designing drives where fast voltage changes during commutation can result in high dV/dt noise levels.

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