Flux-gate technology for accurate current measurement

Electrical Power & Protection

September 2013 Electrical Power & Protection

LEM’s IT current transducers do not use the Hall Effect but are based upon Flux-gate technology, an established and proven technology the company has used for many years and is already the heart of several current and voltage transducer families. Today, LEM uses different versions of Flux-gate technologies, each providing different levels of performance and cost to match a customer’s specific requirements and needs. For the IT family, closed-loop Flux-gate is used as the most efficient and cost effective. Thanks to this technology, accuracies in the parts per million of the nominal magnitude can be achieved. This high-accuracy product range covers transducers for nominal current measurements from 12,5 to 24 kA, while providing overall accuracies at ambient temperature (25°C) of only a few PPM. Thermal offset drifts are also extremely low. Models from 12,5 to 60 A can be used for PCB mounting, whereas models from 60 A to 24 kA are intended for panel or rack-mounting with either on board or separate electronics. In addition, the Flux-gate technologies used provide galvanic isolation for current measurements of all types of waveforms including AC, DC, mixed signal or complex waveform.

Most of the IT transducers feature a round aperture that can accommodate primary conductors of various diameters according to the model used. In addition to the normal current or voltage outputs, these models offer an output indicating the transducer state via normally-open or closed contacts and an external LED. ITZ models provide even more features with additional outputs indicating if the measured current is extremely low or high or if the transducer is in overload, each of these conditions is also supported by a dedicated LED.

The ITB 300-S and ITL 4000-S operate in extended temperature ranges from -40 to 85°C and -40 to 70°C respectively. Although the ITB uses the same technology as the other IT current transducers, it is positioned at a lower price while still offering a level of performance only slightly lower than the other models of the family.

All products are equipped with an electrostatic shield built inside the case to ensure their best immunity against external interference. A shielded output cable and plug are advised to ensure the maximum immunity. IT models react quickly to sudden changes in primary current thanks to the secondary windings working as an excellent current transformer. This feature allows wide bandwidths (up to 800 kHz @ -3 dB). These transducers are CE compliant and also conform to EN 61010-1 for safety requirements.

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Electrical Power & Protection

Flux-gate technology for accurate current measurement

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