Magnetic field based DC current sensor for MGL EFIS's

OK, it's done.
The magnetic DC current sensor is available and we have them in stock.
Details are on the EFIS Accessories page (one of the left buttons) at www.MGLAvionics.co.za including installation.user manual.

It's usable with the latest G2 firmware updates right now and this will be extended to G1 and Enigma shortly.

This simple to use little unit could be useful for non-MGL applications as well. It outputs a pretty accurate 2.5V DC with no field (no current). Voltage increases or decreases depending on field strength (and hence, current in conductor under measurement) and direction of current.

Rainier
CEO MGL Avionics
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Here is the blurb for the new sensor:

This sensor can be used to measure DC currents in aircraft power systems in a wide range from less than +/-4A to as high as +/-120A depending on installation and configuration. The sensor connects to an EFIS system via spare RDAC inputs. Inputs CHT1,CHT2,OIl pressure or Oil temerature can be used and these can also be used on a second RDAC unit (consider a low cost RDAC VD as second RDAC if required). G1 and G2 EFIS systems can support up to 4 of these sensors while Enigma can support 2. These sensors can measure currents bi-directional, for example battery charge/discharge. The major advantage of these sensors is that they can be fitted to existing conductors very easily without a need to break the conductor or require the use current shunts.

Very slick ! And no need to wind the conductor around or through the sensor .
I take it that this is what I need to measure current on my Xtreme when I finally get it ?

What's the cost ?

Marc

777drvr said:

Very slick ! And no need to wind the conductor around or through the sensor .
I take it that this is what I need to measure current on my Xtreme when I finally get it ?

What's the cost ?

Marc

Click to expand...

Yes this will work with the XTreme as well.
You still need to wind the conductor if you want to measure relatively small currents (see the manual for some examples). The picture posted gives a range of over 120A each way but there is some sensitivity to the Earth magnetic field which results in the display of a small "current" depending on which way your aircraft is facing, however considering the large range that is usable, not much of an issue.
Folding the conductor over the sensor or coiling increases the magnetic field caused by a given current and so the sensors range drops but at the same time it gets less affected by stray magnetic fields.

The big thing really is that we have used a new chip that has come out which has solved a big problem with magnetic field current sensors in the past - that of drift. Hall effect sensors (that measure magnetic field) have difficulty in distinguishing between temperature changes and magnetic field changes so that limits their usefullness. This chip uses a clever array of hall-effect sensors in different orientations to eliminate most of the issues and what is left is canceled out by careful calibration. It was only after we found this clever little device that we started taking "non-invasive" current measurement seriously.
After we did some practical tests we announced "The shunt is dead, long live the hall effect sensor". Real nerdy stuff.

Rainier
CEO MGL Avionics

Hi Rainier,

After my post I read the manual . I plan to use it to monitor load on the 8g B lead . Resolution should be + -30 A . Would the strap on/ no coil method be good enough for this application ?

What's the cost ?

Marc

777drvr said:

Hi Rainier,

After my post I read the manual . I plan to use it to monitor load on the 8g B lead . Resolution should be + -30 A . Would the strap on/ no coil method be good enough for this application ?

What's the cost ?

Marc

Click to expand...

Depends on the thickness of the wire.
I'd try the "fold-over" method which is also easy to do. That gives a nominal +/-24A range (perhaps a little more), with the same wire in "strap on" fashion its more like +/-50A.
Golden rule of thumb for this kind of thing is: Make the range as small as needed as that results in the best possible overall performance.
Depending on just how you fit the device you can make yourself any current sensor range you like.
It's of advantage if you can calibrate it using an amp meter (can be done at just one current) - you are completely free to "roll you own" so to speak.

I honestly do not know what the price of this thing is going to end up like in the U.S. - with your currency falling like a rock at the moment it's anybodies guess. We have just shipped 30 of them to Matt, best you contact MGL Avionics USA and get a price.

Rainier
CEO MGL Avionics


Rainier
CEO MGL Avionics