This is in part an email conversation with LabJack support. LJ support comments are quoted.
I’m interested in a low cost system for measuring the current of 120V/60Hz AC lighting circuits using current transducers and a DAQ. The lighting is fluorescent with electronic dimmers, resulting in a non-sine wave AC pattern. The CT output is 1V/2A of current for up to 20 Amperes, suitable for the U3-HV DAQ.
An electric utility tool lending library recommended using a Dent power meter/data logger that measures both current and voltage to use to correlate to the output of the CT as converted by the U3-HV ADC. This way I can run the lights from 0 to 100%, find the correlation between the Dent and the U3, and apply the adjustment in post processing of the ongoing monitoring of lighting current. (opt 1)
A second option is to buy current transducers with lower outputs to be able to use the lower ranges of the U3. I think this would improve resolution? LabJack support, is that right? (opt 2)
A third option is to buy Hall Effect transformers. This is a more expensive option. For more on that see this post: https://forums.labjack.com/index.php?showtopic=7068 . (opt 3)
Here is the LabJack support comments.
“1. I am guessing that the sensor produces 10V peak output for 20 Amps, so we are expecting a sine wave that goes from -10 to +10V peak-to-peak. Sounds fine for AIN0-AIN3 on the U3-HV. You will use stream mode to collect waveform data:
2. Here is a forum topic with a link to the sensor on Amazon, but the cheapest one is now $94:
For more options you want to search for AC current sensors with DC signal output. Ideally ones that can be powered from 5V, as that is what you can get from a LabJack.
3. The Hall Effect sensor still gives you a waveform output like #1. The difference is that I believe they have good high frequency response and thus can accurately transfer distorted waveforms, not just sine waves.”
Related Forum posts I’ve found on this topic:
Part of the reason for this post was to freshen this topic. I saw posts going back to 2006. Electricity hasn’t changed, but products/prices/options have.