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Lower intensity results in HIGHER current draw


jbc455
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I plugged in an ammeter between one of the power plugs on my LOR1602W and the outlet and then turned on channels 1-8 using the Hardware Control.

Those 8 channels drew 4 amps.

I slid the intensity slider to 75% and the current went up to 5.6 amps.

At 40% it read 8 amps!

What gives?

John

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Gee, ya think I could have been holding it upside down? :D

We actually do plan on trying a different meter. I guess I'm just curious if anyone else ever got weird readings.

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If you have a good meter, it reads RMS current. Meaning, you have to give it a nice, full sine wave to make it read correctly. Once you dim a light, you give it a chopped up sine wave, and it will read in error.

You are drawing less current, not more. It takes a really top notch meter to read this kind of thing correctly.

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Actually, the RMS meters are the ones that can correctly read something other than a pure sine wave. Non RMS meters will get messed up with non sine wave loads...

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Now wait second, I'm measuring from the outlet that feeds the box, not between the light string and the box plug. That shouldn't be a "dirty" wave, should it? That should be the actual power the box is drawing.

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There is nothing magic in the controller to clean up the wave form... The controller only draws the power that the loads draw plus a tiny amount for the logic.. If the loads are only drawing current in the second half of each half wave, the inlet cord will only have current on the second half of each half wave...

One case where current actually does go up with dimming... LED strings with capacitive current limiting, and possibly ones with voltage doublers... Dimming causes harmonics, which being a higher frequency than the power line, allow more current through the capacitor... Anyway, the increased current usually kills the string...

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My purely unscientific testing with a kill a watt shows a decrease in amps with fading but the decreases were very small in comparison to the dim factor.

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