I got the residential refrigerator installed in the motorhome. Here are the readings I am getting from the Kill-a-Watt meter, any comments as to what I'm reading here?
-------- V-- A-- W-- VA-- Hz-- PF
INV 123 2.2 161 266 60 .59
LINE 113 1.0 114 114 60 .99
The inverter is a Trace 1500W inverter #L1512, modified sine wave inverter. I'm guessing the Kill-a-Watt won't accuratly read the MSW.
Thanks,
dreamer.
* This post was
edited 06/24/12 02:06pm by dreamer *
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My kill=a=watt unit appears to read the same for all items whether msw inverter or shore power--but the hertz are listed as 15--and my polarity tester has all three lights on.
I have found the kill-a-watt to be a true RMS device. It's quite possible that a device optimized for sine wave operation will be less efficient with another waveform. If you have easy access to the compressor it could be interesting to see if it runs noticeably hotter on MSW.
2009 Fleetwood Icon 24A
Honda Fit dinghy with US Gear brake system
LinkPro battery monitor - EU2000i generator
The sampling rate of the meter does not work with stepped sine waves. Like trying to negotiate 2" wide steps with size 14 shoes. The meter may want to tag steps rather than amplitude peak and valley.
mexbungalows wrote: The sampling rate of the meter does not work with stepped sine waves. Like trying to negotiate 2" wide steps with size 14 shoes. The meter may want to tag steps rather than amplitude peak and valley.
Mex, have you tested this? I've tested mine with MSW and it works very well. Surprised the heck out of me. The only thing I found that threw its readings off was using a CFL lamp as the load.
All Mex is saying is that the Hertz reading might not display correctly--which is why it shows my hertz at 15 instead of 60.
Don, you nailed it. Before digging the hole any deeper I re-tested with a light bulb and a motor. With the light bulb the frequency reads 11 with the inverter, and all the other readings are consistent with shore power. The results with the motor were "interesting". This is a small fan. The frequency with one kill-a-watt was around 6, and the other read "dC". In terms of amps, watts, and VA, on MSW the motor pulled 2/3rds of what it pulls on shore power. It was also pushing noticeably less air. So this particular motor doesn't like MSW but I wouldn't go as far as assuming that all motors react in the same way.
Compare what you believe you have for A/C power to readings taken from electricity grid power. Notice now high the hump in the AC waveform rises and how deep it sags. Compare AC waveforms. Is it a nice, even, not misshapen undulation?
A tool like this will answer any question you may have about effective area under curve of an AC sine wave, and area under curve of a 60 Hz source is what allows battery chargers to work according to design specification, induction motors to start quickly, harmonic distortion (bad), and even noise in a supposedly clean DC source.
Those figures look proper to me, the higher voltage on the INverter will cause a lower power factor for the fridge. (An inductive device).
I have been told though that the Kill-a-watt does not like running on inverters, (either kind) by folks who claim theirs was damaged by running on a TSW inverter of all things.
Mine is pluged into an inverter powered socket, when I travel it is running on a Prosine 2.0 true sine wave inverter, it's does this when I'm wal-marting or boon-docking or flying-j-ing on my annual hike north or south,
It's 7 years old and no problems yet.
So I don't belive everythign I'm told about them not workign on TSW inverters. I don't believe it at all.
Nothin adds excitment like something that is none of your business
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I'm so amazed at how much capability is available for few $$ in the Asian electronics devices. As to the handheld on eBay, I'm too old and obsolete for the small LCD screens and multi-function push buttons. I like the old-fashioned scopes with single-function knobs to turn, although I do sometimes wish for a PC-based scope with its deep storage capability. While looking at the handheld I noticed some nice used Tek storage scopes for $200 to $300. Pretty darn tempting!
I've found that a digital camera can give new life to an old scope, kinda-sorta providing storage capability. Here's an example (voltage and current) of an Onan Microquiet driving a PD converter. And by setting up the correct trigger with single-sweep, startup events can be captured. Other than a lot of convenience, the only big thing a good storage scope adds is random glitch detection.
In the case of the PD converter, the area under the curve is not nearly as significant as the peaks, which explains why it won't perform well with a lousy waveform, even though the RMS voltage is correct.
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