Re: Wattmeter

Tesla List wrote:

> Recently, someone asked about the feasibility of using a watt-hour meter as
> a means of measuring wattage, but noone responded.  Suppose one uses a
> watt-hour meter of the type that is commonly used to bill us for our home
> power useage.  If one monitors just the TC HV transformer (pig, nst, pt)
> for a precise time such as 60 or 100 seconds, will one get a fairly
> accurate indication of average power?  Does mechanical inertia, etc. take
> care of the erratic waveforms it must handle?  I like the almost
> indestructable character of watt-hour meters--they seem to live forever.

An electromechanical watt-hour meter probably measures correctly the
power for arbitrary waveforms. The mechanical inertia is just the filter
that averages the current x voltage product, and is not a problem for
long averages. And as the voltage is essentially a 60 Hz sinusoid for
any reasonable current, active power flows only at 60 Hz, so other
frequency limitations, as inductances of coils in the meter, are of
little importance.

Antonio Carlos M. de Queiroz