Question on phase

[frankwas]

Hi Everyone!

I'm busy working on an assignment, but I'm stuck on a question. :?: How do I calculate the phase difference in a RLC circuit? Also, how do I draw a phasor diagram? I have already calculate XL, XC, XTOT, Z. Please help.

Regards,

Francois.

 

[bmcculla]

If you have Z in terms of jw You just need to separate the equasion into its real and imaginary parts. The real part is the amplitude and the imaginary part is the phase shift. From there you should be able to graph the two functions in terms of frequency. If you remind me what a phasor diagram is I might be able to help you with that too.

Brent

 

[Roff]

If you have Z in terms of jw You just need to separate the equasion into its real and imaginary parts. The real part is the amplitude and the imaginary part is the phase shift. From there you should be able to graph the two functions in terms of frequency. If you remind me what a phasor diagram is I might be able to help you with that too.

Brent

Actually, real and imaginary, when graphed, are orthogonal terms. The real term lies along the horizontal axis, and the imaginary term lies on the vertical axis.
An equation for impedance will generally have a numerator (zeroes) and a denominator (poles). The magnitude of Z is equal to the sum of the vector magnitudes of the zeroes divided by the sum of the vector magnitudes of the poles.
See the attached drawing for a graphical representation of a single pole or zero.
Magnitude of each pole and each zero is the square root of the sum of the squares of the real and imaginary terms for that pole or zero.

The phase of Z is the sum of the angles of the zeroes minus the sum of the angles of the poles.
Phase of each pole or zero is the arctangent of the ratio of imaginary to real for that pole or zero.

How's that for obfuscation?

 

[bmcculla]

Thanks for the clarification Ron; its been a while since I worked with this stuff.

Brent

 

[Roff]

Thanks for the clarification Ron; its been a while since I worked with this stuff.

Brent

Brent, I had dig out my network analysis book from college (it's hand-inscribed on papyrus) for a refresher.