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| Mains current measurement with Halleffect sensor? |
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| Windows9Professional:
--- Quote from: MagicSmoker on September 15, 2019, 11:35:53 am ---EDIT: wait, whut? What coil are you talking about here? --- End quote --- Some copper wrapped around a ferrite core (not that one out of a transformer, just a ferrite stick) But I can easily increase the turns on it if the magnetic field wouldnt be strong enought |
| MagicSmoker:
--- Quote from: Windows9Professional on September 15, 2019, 11:48:13 am ---... A current sensing transformer would only work with AC and I planned to calibrate it with DC ... --- End quote --- This makes no sense, really. A mains-frequency current transformer won't need calibration since its output will be as precise as the value of the burden resistor and the turns ratio, and will range in price from 3-15 Euros depending on form factor and current range. For example, this part from Triad Magnetics has a 1:500 ratio and max primary current of 30A for $3.37: https://www.digikey.com/product-detail/en/triad-magnetics/CSE187L/237-1103-ND/242546 Just wire a burden resistor across the output to convert the secondary current into a voltage and read directly with your scope. For example, a 50 Ohm burden resistor will give 3V out with 30A through the primary. Easy-peasy. |
| Windows9Professional:
--- Quote from: MagicSmoker on September 15, 2019, 01:15:37 pm --- This makes no sense, really. --- End quote --- ... Oh, you're right.. To be honest, I didn't notice that bevore... Does a CST blur out all detail of the current waveform or is there at least some detail? (f.e. when measuring a switch-mode power supply, there's some switch noise as far as I know) Edit: the example above is bullshit... I mean when measuring f.e. an iron-core transformer |
| schmitt trigger:
The downside of a CT, is that it can’t measure DC, or AC with a DC component. Otherwise they are very sturdy and don’t require external a power source. Cheap CTs will also have some bandwidth limits, but there are good wideband CTs, although they are not cheap. https://www.pearsonelectronics.com/ To your idea of hall-cell sensing; Allegro Microsystem and others already have such devices. The beauty of such devices is that it incorporates the features and processing circuitry required to make an accurate IC current sensor. |
| MagicSmoker:
--- Quote from: Windows9Professional on September 15, 2019, 04:44:59 pm ---Does a CST blur out all detail of the current waveform or is there at least some detail? (f.e. when measuring a switch-mode power supply, there's some switch noise as far as I know)... --- End quote --- The cheapest current transformers with plain old laminated silicon steel E cores (like the one I linked to previously) won't have terribly high bandwidth so wouldn't be ideal for observing the waveform into something that draws peaky currents with high harmonic content, like a switcher. If that's what you want to do then a Hall effect sensor intended for mains applications like the ones from Allegro that @schmitt trigger mentioned would be better. |
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