Energy meters domestic plug in wall type
Energy meters domestic plug in wall type
(OP)
There are plenty of domestic plug-in electric energy meters for monitoring consumption about the home or office.
These will refresh display every 10-20 seconds.
I wish to monitor a rapidly switching device and I am concerned the energy meter may not be getting a true value of consumption if the sampling and switching are out of step.
Does anybody know if a typical energy meter for about $15 has the smarts to overcome the worry I have?
http://www.ustudy.in/node/6449
Thanks
These will refresh display every 10-20 seconds.
I wish to monitor a rapidly switching device and I am concerned the energy meter may not be getting a true value of consumption if the sampling and switching are out of step.
Does anybody know if a typical energy meter for about $15 has the smarts to overcome the worry I have?
http://www.ustudy.in/node/6449
Thanks





RE: Energy meters domestic plug in wall type
It would make sense that the meter would sample faster than the display update, and average the results. Or perhaps it would integrate under the curve using analog circuitry. But maybe not... ...perhaps it simply samples.
In the long run, even samples should average out to the correct value.
RE: Energy meters domestic plug in wall type
RE: Energy meters domestic plug in wall type
RE: Energy meters domestic plug in wall type
Over any reasonably long period of time, unlucky synchronization is unlikely. The meter should catch the On Power pulses in proportion to the duty cycle, thus there's a good chance that the averages will work out. Unless something else is going on, which might be the OP's fundamental concern.
If the OP can determine the On Power, the Off Power, and the duty cycle, and assuming they are stable - then it's obviously trivial to calculate the precise average power; for comparison with what the $20 meter says.
If the OP needs dynamic measurements, then use a different method.
RE: Energy meters domestic plug in wall type
The application is a 3 kW heater I wish to test in the field. I cant predict normal cycling of heater. It is a prety rough test so I cant expect too much accuracy but I just wish to limit unknowns.
Perhaps I am being too cautious and the issues will average themselves out.
In lab tests we use much more sophisticated instruments so I should test the accuracy myself against these and see what sort of correlation I get. However this is often out of my control.
Could anybody recommend a good low cost consumer energy meter (<$50) for running over week or are they all prety much the same?
Thanks again
RE: Energy meters domestic plug in wall type
RE: Energy meters domestic plug in wall type
Watt's Up Pro is higher than your bogey: http://www.ebay.com/sch/i.html?_from=R40%7CR40&..., but it's able to datalog to a PC at 1-second intervals: https://www.wattsupmeters.com/secure/downloads/man...
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RE: Energy meters domestic plug in wall type
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Energy meters domestic plug in wall type
asimpson; The WattsUp unit I have has worked very well for me.
This from their highlights:
https://www.wattsupmeters.com/secure/products.php?pn=0
Keith Cress
kcress - http://www.flaminsystems.com
RE: Energy meters domestic plug in wall type
Z
RE: Energy meters domestic plug in wall type
We had (have) a need for a customer to accurately measure rms current on load that is cyclic at rate of 100msec to 3000msec. during each cycle, the load changes from .5 to 18 amps. we found no wattmeter on the market for less than thousands of dollars that did not have > 1 sec sample rate, so none could make our measurements... I ended up providing a true rms averaging digital current meter and CT transformer that would rms 4000 samples/sec over adjustable 1-60 second period. It agreed with our rms scope readings. Our customer had to then multiply this true rms current by the 230v 1ph to get true rms watts.
I say this because even your link says it samples no faster than 1 sec. The only model that says it samples 1000's of times per sec is the cheap 'watts up' model, and it appears to just give instantaneous peak and min values and does not seem to collect samples over time like the more expensive ones do? the more expensive ones are all limited 1 sec or longer sample rates also. Am I reading the data wrong on these? I hope so, as I would love to be able to provide a $100 true rms wattmeter that samples faster than 1/sec!
www.KilroyWasHere<dot>com
RE: Energy meters domestic plug in wall type
As for the sample period the low-end one I have is, I believe, the same as the the one we're seeing on the site. While I never knew it sampled above 1kHz it has always appeared to be very fast to me. The numbers seem to change instantly as compared to occasional updating like most DMMs.
It does cough-up rational peak currents of values you'd expect from inrush. The WattsUp came out just before all the power calc chips hit the market so I believe they did a nice hardcore read the instantaneous current and voltage and multiply together rapidly, type design. As for logging it really doesn't "log" it totalizes. It will tell you the duty cycle, kwhrs, average amps, etc. You can program your energy cost and it will give you a running energy cost. It's very nice for assaying stuff around your house. Plug each item into it and leave for 24 hours and log it to a notebook. Wander around the house and do everything and in two weeks you know who the energy hogs are. Refer, cable box, too-large flat screen, etc. :)
I think the ad-speak is a bit confused in that I believe the newer versions work the same but only log the data second by second.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Energy meters domestic plug in wall type
That is the total consumption may be correct for your duty cycle even though you can not see the actual duty cycle with the 1 second update.
I looked up the manual for the Watts Up unit and was not reasured.
Do you need total consumption or do you also need the load profile?
Bill
--------------------
"Why not the best?"
Jimmy Carter