Calibrating an AC wattmeter

[NeoPTLD]

http://www.valhallascientific.com/data-sheets/pdfs/2100_DS.pdf

The procedure isn't overly complicated, but I don't have access to calibration equipment.

Anyone know where I can send the unit to get the above calibration procedure done and how much it would cost?

I would prefer something local, but reasonable quality at lowest cost is my priority.

 

[dkozloski]

The manufacturer of any test equipment can either calibrate the equipment or direct you to the nearest calibration lab. Uncalibrated test equipment is both worthless and dangerous.

 

[DrPizza]

Hey, while we're on the topic, anyone know of something relatively inexpensive I can use at home to monitor power consumption? I have a hard time believing I'm using as many kw-hrs as the electric company says. (do electric meters become defective with any appreciable frequency?)

edit: for what it's worth, I found on one site - from an electric company - that they slow down when defective; not speed up. But, that's exactly what I was told about my water meter - an assertion that proved to be incorrect. If it matters, my electric meter is one of those digital ones that they can read by just driving by.

 

[PowerEngineer]

It is generally true that the failure mechanisms for electromechanical devices such as the traditional watt-hour meters on houses will cause them to run slower. So the real question is: does your house meter have a disk that rotates? If so, it's electromechanical. There are new electronic meters that have no mechanical parts, and I have no idea how they misbehave when something in them fails. There are add-on remote metering devices for electromechanical meters, so that doesn't mean that yours is not electromechanical.

 

[NeoPTLD]

Originally posted by: dkozloski
The manufacturer of any test equipment can either calibrate the equipment or direct you to the nearest calibration lab. Uncalibrated test equipment is both worthless and dangerous.

I got a quote from one company.
$165. Screw that .

I don't need official traceable calibration certificate. I just need to find a place that has reasonable competent technicians and all the calibration standards needed for this particular instrument. I got the meter at a surplus store and I just gotta get rid of some 12 years of drift the instrument has accumulated.

 

[dkozloski]

If you want to dance you have to pay the piper.

 

[DrPizza]

Originally posted by: PowerEngineer

It is generally true that the failure mechanisms for electromechanical devices such as the traditional watt-hour meters on houses will cause them to run slower. So the real question is: does your house meter have a disk that rotates? If so, it's electromechanical. There are new electronic meters that have no mechanical parts, and I have no idea how they misbehave when something in them fails. There are add-on remote metering devices for electromechanical meters, so that doesn't mean that yours is not electromechanical.

I really wish it was an electromechanical meter... It's so nice to be able to have someone stand by the meter, turn off all the breakers, and turn them on one at a time so you can troubleshoot.. Maybe I have an appliance that is suddenly using much more power than it should. The house is/was an electrical nightmare; although I've fixed most of the problems. The last known remaining problem is the barn, all of which is on one circuit: 200 feet of 12/2 just to reach the barn from the breaker panel. For now, all I dare to run is a few fluorecent lights. Then, I have to balance the rest of the circuits, especially correcting the problem of the entire kitchen being on one circuit. (And, simultaneously, there are single outlets on one circuit.) Just a weekend project though, except the barn.

 

[dkozloski]

Dr.Pizza. go to your local electrical supply store and get an AmProbe clampon ammeter. It can be used any place you can separate out the wires so you can clamp it on the hot wire. Who cares what a wattmeter reads. All you're interested in is the draw to see if there is a sneak circuit somplace. If you see a wire with current flow that should be dead you have the culprit. I've been using mine for forty years. If there is some question about your power meter just call your local power utility and they will come out and swap it for a freshly calibrated unit. On top of that they usually have data logging equipment they can hook up and leave so the feed can be monitored over time.