I recently purchased 2 little voltmeters they look like the sort that would go in a control or instrument panel they are connected with just 2 wires which provide the operating supply ( they light up green and red) however the green one states it will work between 20and 500 volts and the red one between 60 and 480 volts. When they are both on the green one indicates normally around 241 volts the red one shows 235 volts why the discrepancy I know it's not much but makes you wonder if one of them is lying. Secondly I've noticed that the green one tracks voltage changes faster than the red one and that a few times the green one jumps down to 238 then up to 241 multiple times while the red one stays the same and I think can see a slight flicker in my filament lamps when this is happening incidentally both meters are connected to the same plug a 2 pin 5 amp one
Point is that any measuring device has a degree of error. There are some incredibly accurate clocks, for example even pendulum ones can be accurate to within a second per year.
I would expect that my best Rabone Chesterman steel rule is pretty close to a foot long (at 20 deg C) but even so. I doubt that I could measure anything within 20 thou, so that's a 1:6000 error.
So my expensive Megger MFT starts to look pretty poor at +/- 1%.
Conclusion is, Kelly, that I think that your meters are behaving within spec.
Point is that any measuring device has a degree of error. There are some incredibly accurate clocks, for example even pendulum ones can be accurate to within a second per year.
I would expect that my best Rabone Chesterman steel rule is pretty close to a foot long (at 20 deg C) but even so. I doubt that I could measure anything within 20 thou, so that's a 1:6000 error.
So my expensive Megger MFT starts to look pretty poor at +/- 1%.
Conclusion is, Kelly, that I think that your meters are behaving within spec.
