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Re: Wattmeters

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

At 12:08 PM 7/24/2005, you wrote:
.......


in generally - how wide is the spectrum of the current drawing by real
TCs - without mains filters, power correctors?

My DRSSTC draws small current peaks of about 25A from the 240v line, even though the real power draw is only 500W. It's the usual story with a bridge rectifier feeding a big capacitor (3300uF in my case) 
.........

I used MicroSim to do the spectrum on the AC line for my DRSSTC. It said that almost all of the power was at 60, 180, and 300Hz

http://hot-streamer.com/temp/DRSSTC-InputCurrent-FFT.gif

The iron vane ammeter I got is good to 400Hz so it works just fine even if the input current is nasty. I do have RC filter resistors in the AC line however which may substantially cut down the higher harmonics too.

Cheers,

        Terry