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EEVblog 1446 - Analog Watt Hour Meters are AMAZING!


Analog Watt Hour energy meters are fascinating! How they work, teardown, and experiments.

Thanks to Max Button for sending this in to the mailbag.

00:00 - Watt Hour Energy Meters
02:11 - Teardown
05:13 - What's to stop it taking off?
06:40 - Does it work? Testing with a load.
07:24 - Can you get free electicity with a neodymium magnet?
08:14 - Timelapse of no load creepage
08:49 - Anti creep holes
10:45 - When this baby hits 88 MPH you're gonna see some serious spin!
19:06 - Theory of Operation
24:00 - Interesting Design - Jewel bearings
25:07 - Interesting Design - Magnetic temperature compensation
26:58 - Interesting Design - Full load compensation
27:40 - Interesting Design - Dimples

This is how serious they take their metering:
This model meter was cancelled from use in 2012:

This is the topic I was very interested in, thank you for this great overview!  :-+

piano wire & 1mm drill is what the indoor gardners use to keep costs down. :-X

The pyramid like dimples in the disk @ 28:00 are an artifact of the production process.
The sheet metal is made in big rolls, and it's not very flat. The press that stamps the disks out of the sheet metal also presses in the dimples. It first presses the (slightly bent) plate flat, and then presses further to put the dimples in, and this introduces much more local stress into the material then the slight bending force. The end result is that the disk comes out of the press flat, but with dimples.

This was fairly common for making steel sheets flatter in all kinds of semi-precise mechanisms. such as the internals of compact cassette players.

I do not know what the rectangular shiny sections on the disk are for. My meter at home also has them.
I'm guessing, but it may be a calibration correction for the thickness of the disk. I assume the thickness of the disk has an influence on the location or amount of eddy currents in the disk


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