New Ultra-Accurate current sensors
from LEM

LEM expands its range of high accuracy transducers for non-intrusive and isolated measurement of DC, AC and pulsed nominal current of 100 – 2000 A.

+10 to +40 or +50°C temperature range is usually offered by the traditional high accuracy transducer, the IN series 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 (e.g. MRI, proton therapy etc.), precision motor controllers and metering.

LEM used patented innovations for these new transducers. A maximum signal processing has been treated in the digital domain, and a new approach to the 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 driving a ‘ripple compensation coil’ whose amplitude and phase are adjusted during the calibration of each transducer.


The use of fluxgate technology in transducers for precise current measurement is well-known. However, it has some limitations linked to the ripple derived from the excitation voltage. LEM’s innovation takes fluxgate current transducers to previously unachieved performance levels through digital technology.


  • Best-in-class accuracy: excellent linearity and minimum electrical offset
  • Broad frequency bandwidth (up to 1.1 MHz @±3 dB)
  • Compact design with largest aperture for cables and busbars
  • Really good immunity from external fields
  • Overcurrent and protection embedded by design
  • Extended operating temperature range: -40..+85 °C
  • Extremely high stability (0.15 ppm/month)


  • Closed loop (compensated) current transducers using an extremely accurate zero flux detector
  • 9-pin D-Sub male secondary connector
  • Status signal to indicate the transducer state
  • LED indicator confirms normal operation
  • Metal housing to improve immunity to EMC & power dissipation
  • Transducer identification
  • Large apertures for cables and busbars