[Amps] transformers

[Peter Chadwick]

Tom said:
>By the way, a typical o-scope is one of the least reliable 
common ways to read power. First, scopes have passband 
ripple. They are designed of good response to a stepped 
waveform, frequency response flatness (or lack of ripple) is 
secondary. Second, they are susceptible to common mode on 
probe leads. Third, they don't store the absolute peaks 
unless you have a storage scope and are lucky enough to 
catch the peak. Fourth, any error they do have is compounded 
by the fact power is a square of the measured voltage, so 
the error is squared. Fifth, they are load resistance 
critical.<
Sixth: most scopes are only good to about 5% measurement uncertainty anyway, so from Tom's point 4, that error gets squared. And if there's a probe used, that adds to the uncertainty, too. OK for a rough reading...
73
Peter G3RZP