NON-CONTACT MAGNETIC-SENSING DC CURRENT MEASUREMENT BY FLUXGATE

Claiming a first for the Marine market, Autonnic has just launched a DC current magnetic metering system ideally suited to marine electrical systems.  First shown at METS16 the A4710 has no electrical contact with the wire which carries the current and so it can just be clipped any insulated wire; there is no interruption or re-wiring or termination required because it measures amount and the direction by the magnetic field which the current creates.

Measuring high currents by this means is relatively straight-forward but what Autonnic has done is to be good at low-currents too. The very high sensitivity and stability inherent in fluxgate technology means this method can now be used in low-cost Battery Monitoring applications. This is particularly demanding because the integration of small currents in a stable way over long periods of time is just as important to charge-management as a good high-current performance.

Not only it’s the device isolated electrically from the current, so that it will work on systems of any voltage, but it is also impervious to overload.  Massive overload currents, hugely in excess of its 50A rating, which would cause a shunt-based system to overheat, merely cause this device to suspend measurement and then to resume when the current falls back in range.

This + or – 50A device is the first in a series which will include higher and lower current versions.

The A4710 can directly use battery cables up to 13mm diameter and Autonnic supplies spacers to accommodate thinner conductors.

The analogue outputs can be used directly by conventional meters and include a voltage for each direction.  The digital output is a NMEA-0183 type of serial TTL data stream for direct integration with charge management, marine display systems or for feeding into on-board computer power management systems.

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