The Need for High Precision Current Measurement
High precision current measurement addresses applications where standard industrial sensors (typically ±0.5% to ±1% accuracy) are insufficient. These applications include calibration laboratories, particle accelerator magnets, superconducting coil testing, and high-end power electronics characterization. In these environments, current must be measured with accuracy measured in parts per million (ppm), requiring specialized transducer technologies.
LEM’s IT series represents the pinnacle of current measurement technology, using Fluxgate technology to achieve accuracy levels that were previously only possible with laboratory-grade instruments.
Fluxgate Technology: The Key to PPM Accuracy
Fluxgate technology is fundamentally different from Hall-effect measurement. Instead of relying on the Hall voltage generated by a semiconductor material, Fluxgate sensors exploit the non-linear magnetic properties of a saturable core. This approach offers several key advantages for high-precision measurement:
Zero Offset at Zero Current
Unlike Hall-effect sensors that have an inherent offset voltage, Fluxgate sensors produce zero output when the primary current is zero. This eliminates one of the major sources of measurement error and simplifies calibration.
Excellent Temperature Stability
The Fluxgate principle is inherently less sensitive to temperature changes than Hall-effect sensors. The IT series achieves offset drift as low as 0.05 ppm/K and sensitivity drift of 10 ppm/K, ensuring measurement accuracy is maintained across wide temperature ranges.
Outstanding Long-Term Stability
Fluxgate sensors exhibit minimal long-term drift, typically less than 10 ppm per year. This means that calibration intervals can be extended significantly, reducing maintenance costs and downtime in continuous operation applications.
LEM IT Series: Key Specifications
IT Series — Fluxgate Current Transducers
- Measuring range: ±5 A to ±25,000 A
- Accuracy: ±0.05% of IPN
- Resolution: 1 ppm of IPN
- Offset drift: < 0.05 ppm/K
- Sensitivity drift: < 10 ppm/K
- Bandwidth: DC to 500 kHz
- Operating temperature: -10°C to +50°C
- Technology: Closed-loop Fluxgate
Typical High Precision Applications
The IT series is deployed in the most demanding measurement environments worldwide:
- Calibration laboratories: serving as reference standards for current sensor calibration
- Particle accelerators: measuring magnet excitation currents with ppm-level accuracy
- Superconducting coil testing: characterizing high-field superconducting magnets
- Power electronics research: measuring high-frequency current waveforms with precision
- Battery testing systems: ensuring accurate current measurement for battery characterization
- Metrology institutes: maintaining national current measurement standards
