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Shunt vs Hall Effect
#11
(04-08-2017, 07:23 AM)station240 Wrote: There are three types of current sensors:
a) Shunt Resistor + opamp (of some sort) - Measure voltage drop across resistor
b) Current Transformer - 1 turn from cable, multiple turns for sensor output
c) Hall Effect Current Sensor - 1 turn from cable, silicon based magnetic sensor to sense current.

The Current Transformer and Hall effect Sensor both work on the basic principle that current flowing though a cable generates a magnet field, which is then picked up and amplified. As they are magnetic sensors that respond to low level signals, they will pick up noise. You can either filter the noise on the output, say get rid of AC signals if your only measuring DC, or shield the sensor from the noise in the first place.

Accuracy of all three methods of sensing current depend entirely on what you buy. I've got hall effect current sensors good for 0.1%, you'll struggle to find current shunt resistors that accurate.

When im allowed i would like to add a 4th type of current sensor similar to HE but more accurate (especially the zero offset) working with a different physical principle. Its a current transformer working with electronic as a compensation technique providing directly voltage per Amp, from DC up to 100 kHz. Of course isolated, accuracy close to the 0.1 % region possible. Different models with internal or external electronic.
There are no clip around models (by principle), you have to feed through.

Producer is  VAC (Vacuumschmelze) in Germany. There may be others I dont know.
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#12
(05-14-2018, 07:09 AM)Cherry67 Wrote: When im allowed i would like to add a 4th type of current sensor similar to HE but more accurate (especially the zero offset) working with a different physical principle. Its a current transformer working with electronic as a compensation technique providing directly voltage per Amp, from DC up to 100 kHz. Of course isolated, accuracy close to the 0.1 % region possible. Different models with internal or external electronic.
There are no clip around models (by principle), you have to feed through.

Producer is  VAC (Vacuumschmelze) in Germany. There may be others I dont know.

Do you have a link to this device? Sounds interesting. Always up to learning more about this stuff Smile
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#13
Sorry for late answer.

https://www.vacuumschmelze.de/fileadmin/..._final.pdf

https://www.pollin.de/p/aktiver-stromsen...gKuEvD_BwE

single 5 Volts supply:
https://eu.mouser.com/datasheet/2/599/46...240710.pdf
https://www.vacuumschmelze.de/fileadmin/...6-X160.pdf

German distributor
https://www.buerklin.com/de/search?text=stromsensor+vac

https://www.vacuumschmelze.com/index.php?id=404

https://www.radiomuseum.org/forumdata/up..._en~~2.pdf
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#14
Ahhh, that's an interesting device. Thanks for added info. I'll be looking at more of these to get a better grasp on how they work and how to implement them.
Proceed with caution. Knowledge is Power! Literally! Cool 
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#15
In general, i can say the accuracy is better than HE.
Better linearity, better accuracy, lower zero Offset.

The technical prinziple is different. 
While HE basically uses a transformer, and measures the flux in the core with an HE, the VAC current sensor have a compensation principle. The sensor does not measure the flux, but controls a compensation winding to compensate the flux in the core to zero. Then the current in the compensation winding equals the Measurement Signal.



(the picture is taken from public info from VAC)


Due to the accuracy, even higher currents can be measured with acceptable low current resolution, and without shunt losses.
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#16
The "losses" in a decent shunt are negligibly small, the resistance is often less than your battery cables & typically develp only eg 75mV across them at rated max current.
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#17
(06-14-2018, 10:46 AM)Redpacket Wrote: The "losses" in a decent shunt are negligibly small, the resistance is often less than your battery cables & typically develp only eg 75mV across them at rated max current.

You are correct. yet, at peak power of some 100 Amps that still makes a few watts. Not too nagging in form of losses, but a heat to dissipate of several watts. The losses in cables, and switches, fuses, and connectors are present as well.
Its just another 75 mV, as you say. In an 48 Volts system still different to look at, as in a 24V.
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