1000A transducer with wide temperature range

| Information and Communication Technology

1000A current measurement transducer

A new high accuracy transducer has been developed for measurement of high electrical currents in applications outside the laboratory.

LEM has expanded its range of high accuracy transducers with the IN 1000-S for non-intrusive and isolated measurement of DC, AC and pulsed nominal current of 1000A. LEM already launched a 2000 A model last year as the first model of this range, re-inventing fluxgate technology.

Temperature ranges of +10 to +40 or +50°C are usually offered by traditional high accuracy 1000 A transducers, whereas the IN 1000-S model provides an extended operating temperature range of -40 to +85°C, allowing it to be used in a wider range of applications in addition to labs. These applications include: test equipment for traditional industrial applications, medical equipment (eg MRI, proton therapy etc), precision motor controllers and metering.

LEM used patented innovations for this new transducer. Maximum signal processing was treated in the digital domain and a new approach to fluxgate technology architecture has been applied for the ripple cancellation of the fluxgate drive frequency. The result is a compact transducer, maintaining its high accuracy over a wider temperature range, with reduced noise level vs the previous generation.

Processing the signal in the digital domain brings complete immunity to temperature effects, interference and supply voltage variation after the ADC. This contributes to offset and offset drift improvement.

The reduction of the interference or ripple from the fluxgate driving signal at a fixed frequency is as a result of the use of the DSP (Digital Signal Processor). Higher frequency harmonics have been reduced.

The remaining interference has been eliminated by using a ‘ripple compensation coil’ whose amplitude and phase are adjusted during the calibration of each transducer.

After calibration, the remaining peak-to-peak ripple is less than 34 ppm, relative to the full-scale transducer output, over the full -40C to 85C operating temperature range.

These innovations contribute to providing a high performance across the extended temperature range, delivering extremely high accuracy with linearity and low offset over the temperature range of better than 3 ppm and 19.5 ppm respectively.

The IN 1000-S has been designed to operate from a bipolar +/-15 V DC power supply and will accommodate round primary conductors of up to 38.2 mm diameter. In addition to its normal current output, the transducer offers an additional output indicating the transducer state (low or high output levels) and an external LED showing normal operation.

An equivalent product would usually be made up of 2 parts, the measuring head and the treatment electronics, while this new model has a compact integrated design, allowing a variety of panel mounting topologies (flat or vertical) to be used.

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