[Amps] Volt-watt meter

[Will Matney]

Gary,

That's exactly what I was thinking and still wouldn't be really for sure on 100% accuracy. Really, a few percent off wouldn't be that bad for what its intended purpose was for. However, one would like to be as accurate as possible too. I bought this to measure the wattage on transformers after they were built ( load and no load ). My guess is that those bulbs aren't too accurate on their ratings, or they rated them at 120 volts, and the line was a little lower. To be honest, without digging the meter out, I cant recall the maximum readings, but I think on low, it went to about 1 kW and on high maybe 3.5 kW. I'll try to dig it out later today and see.

Thanks,

Will

*********** REPLY SEPARATOR  ***********

On 4/22/05 at 10:43 AM Gary Schafer wrote:

>What is full scale power of the meter?
>
>You could use a precision resistor in series with the load and measure 
>the voltage across the resistor to get current. However keep in mind 
>that most ac voltmeters don't do a very good job. If you get with in a 
>few percent you will be doing good.
>
>73
>Gary  K4FMX
>
>
>Will Matney wrote:
>> I have a Simpson volt-watt meter here I'm thinking about getting
>calibrated. The thing is, I'm not really sure how accurate it is. After I
>bought it, I tried it out on a lamp in the house using a 100 watt buld.
>Something didn't jive about the watt reading when I calculated the wattage
>from the line voltage shown as the meter showed a lower wattage. I wonder
>just how accurate those bulb ratings are? Simpson is known for good
>accuracy because of their meter movements, but I'm not too sure about
>this. I'd like to test it again before I pay a fortune for calibration on
>it. I thought of using a transformer but then your not sure what the power
>actually is due to losses. I don't have any power resistors large enough
>handy to at least get a 1/2 scale reading. What might be a good circuit
>I'm not thinking of to test this? Note; this meter is designed for power
>readings on a 120 or 240 Vac line.
>> 
>> Thanks,
>> 
>> Will
>> 
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