Explanation of how kilowatt-hour meters work (electromechanical)

[xrunner]

Nope, no microcontrollers in this baby. No transistors or logic gates. If you're looking for that, this video ain't your cup of tea.

But interesting how they used basic electrical and magnetic theory to make the instrument.

[JoeyP]

That was interesting. I'd always wondered what they used to provide a predictable source of resistance to the force generated by the varying magnetic field. Clever to use permanent magnets and associated eddy current related force, since they would stay relatively constant over a long period of time. Also interesting about the couple of hacks they use to account for friction at very low power levels.

At one time in my early youth, I had a job rebuilding gas meters - the type you have outside your house metering your gas service. They are basically very similar to a steam engine driven by gas moving through the pipes. They (at that time) used leather bellows instead of cylinders. BTW, they virtually always slow down with age, which gives the customer a better and better deal over time. Moral of the story - never complain to the gas company that your meter is not accurate unless you're absolutely sure of it. They will replace it with a freshly overhauled and calibrated unit, and your bill will likely go up!

[SeanB]

Had the same with the bulk water meter, did not want to roll over to all zeros until I did a little percussive maintenance on it while it was at full flow ( opened the 2 fire hose standpipes to full to get there) and used a 4 lb hammer to gently tap the housing to jar it loose. Did not want it replaced as it was worn nicely and had a little droop, plus the metro wanted us to pay the costs of the new meter and the installation as well.

There was one garage with a similar fault in the one pump, I filled my tank slowly ( blocked breather pipe) and found that a full tank was 15l of fuel as opposed to 45. Next day I called the head office and spoke to the technical manager and about a week later the whole pump was replaced. they are calibrated at a high flow rate, so the wear on the positive displacement pump is not noticed during the testing with a calibrated volume tank they use.