Go Down

Topic: ACS712 problem when sensing an inductive load. (Read 2 times) previous topic - next topic

MarkT

Well I'd not describe my mains as sinusoidal - too many SMPS's on the line:


Actually its capacitive pick-up from a mains cable, so not quite accurate,
but safer than trying to rig up a resistive divider from 240V ac.

[ the current waveform is left to the imagination! ]
[ I won't respond to messages, use the forum please ]

jackrae

If you look at the ripple on the mains base frequency you will observe it is consistant at 12 times per cycle.  This suggests it may well be inductive interference from a motor or poorly constructed generator and possibly illustrates the point I was making about pole passing frequency.  The noise could be from a neighbours motor on the same phase from the substation as yourself.  This type of problem will only get greater as air and ground source heat pumps become more popular.  No doubt some of the cheaper PV invertors will also contribute.

On the subject of test meter accuracy on AC measurement.  Some of these meters are so cheap there is every possibility that they use a simple rectifier and RC filter to produce the so-called RMS signal to feed the DC section of the measuring device.  As such they will be calibrated for a sinusoidal waveform and any variation from that form will introduce error.

Go Up