PSIM wattmeter

Discussion in 'General Electronics Chat' started by almotions, Aug 3, 2009.

  1. almotions

    Thread Starter Active Member

    Feb 6, 2009
    Hi everyone,
    I have some problems using the wattmeter in PSIM software.Assumming a
    R=10Ohms load is supplied with 110 Vpeak single phase source at 60hz. According to P=VI,the wattmeter should show me 605Watts. The wattmeter implements a low pass filter with a variable cut off frequency which can be set by the user. Apparently,when i set this frequency to 68.5Hz ,the wattmeter gives me an approximate value of 605 Watts, but when i set it to 60Hz,it gives me a reading of 597Watts.
    My question is what is actually this cutoff frequency?Is it the frequency at -3db point or the exact frequency which we want to attenuate everything above it? and if i set the cutoff frequency to 30Hz,why does the wattmeter show me a value of 586 watts which is quite high since the fundamental frequency is 60Hz?
    Please advice.