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Faster open-loop current sensors work up to 250A

22 May, 2014

The Swiss current and voltage sensing specialist LEM has announced a series of current transducers capable of measuring up to 250A. The HO sensors offer a choice of panel, busbar or PCB mounting, integrating the conductor or using an aperture measuring 15 x 8mm.

The transducers offer offset and gain drifts which are said to be up to twice as accurate as the previous generation across a temperature range of -40 to +105°C, and to have a faster response time of 2.5–3.5µs.

The transducers measure DC, AC, and pulsed signals using an open-loop Hall-effect Asic chip. The open-loop performance is said to approach that of closed-loop transducers, improving control and system efficiency at a much lower price.

Operating from 3.3V or 5V supplies, the sensors can measure up to 2.5 times the primary nominal current and include an extra pin for detecting over-currents. They also provide fault reporting in the event of memory corruption.

The panel-mounting versions offer up to three interchangeable mounts: one vertical, one horizontal and one on the busbar (when used).

LEM's high-current transducers come in a choice of formats

Typically, the analogue output voltages are converted into a digital value by a device which needs a reference voltage provided by the HO. However, the transducers can also be configured to take measurements relative to an external reference voltage.

Applications include variable speed drives, static converters for DC motor drives, and robotics.

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