WARNING - Newbie, question.
I have a cesspit bubbler (air pump) made by Secoh EL-S 100
The 100 bit is in reference to it consuming 100w... Its label says 100w as does all the tech blurb I can find.
I can isolate the pump from within the house and Emonpi shows 160w burden by turning it on / off.
I've tried it multiple times but its the same within a few watts each time.
Is my emonpi wrong, is the pump incorrectly rated?
I also have a water pump for my well (Mono CMS) rated 180w and its spot on on emonpi.
Re: power rating W on motor and W use
Does your EmonPi have an AC connection? If not it's measuring apparent power, and it's possible the power factor for your air pump is only 100/160 = 0.625
Re: power rating W on motor and W use
yes it has an AC connection as its the 'solar' emonpi. currently reading 243.75v
Re: power rating W on motor and W use
If 100 W is the shaft output power, your pump has an efficiency of 62.5%, and while low, I'd have expected 70 - 80%, that's not totally unreasonable for a small motor.
Re: power rating W on motor and W use
Interesting device. The motive power is from an oscillating solenoid, so this falls into the class of variable reluctance motors. The current waveform is highly distorted and of course lagging due to the inductive nature.
I'd expect extracting accurate true power from that current waveform is a challenge - the spec sheet suggests less than 100W provided you are operating in the optimum back pressure regime.
Re: power rating W on motor and W use
ah... ok many thanks for the explanation. So in that case my 24hr kwh are probably slightly out?
I have an optical reader on the meter but not yet sure I've set it up correctly.. its just counting & not being used I think... Time to investigate
Re: power rating W on motor and W use
Ye Gods! I didn't find that spec sheet - it explains a lot. In its absence, I was assuming it would be a small induction motor.
I presume you haven't checked the phase calibration of your emonPi. As the power factor is likely to be quite low, correction of the phase errors, which tend not to show up at near unity power factor, becomes more important, so I expect at least part of the error could be there.