Basic question on visualising AC voltage signal in scope

Question

ck12345 2016-5-20

评论： ck12345 2016-5-21

Im trying to visualise a sinusoidally varying voltage which is in complex form. Now I know that this is sinusoidal as it comes from an AC generator.

But when I connect it to a scope all i get is a flat line.

What am I doing wrong?

Answer 1

Sebastian Castro 2016-5-20

I'm guessing the model you're using is in phasor mode, as that voltage measurement is a complex phasor.

The way phasor mode works, this is expected. We can determine that, for each phase voltage you are plotting on that scope:

The magnitude sqrt(Real^2 + Imag^2) is the amplitude of the sinusoid
The phase atan2(Imag,Real) is the phase of the sinusoid
The frequency is assumed to be a fundamental frequency specified in the powergui block (typically 50 or 60 Hz)

- Sebastian

ck12345 2016-5-21

I tried that but still the magnitude is a flat line.

I don't think its giving me the instantaneous value. Rather what an AC voltmeter would measure. How do I get it to measure the instantaneous value?