RLC, Single frequency AC analysis results do not match hand caculated results.

[MAGNOTRAN]

On a simple RLC simulation single frequency AC analysis, the resultant magnitudes are off by factor of 10. Phase angle values are all correct and match the calculated values. On a different example worked out in a text book, same results.What am I doing wrong?   Also, how do you change the AC source from RMS to peak or vise versa? Thanks.

[Tien_P]

HI,

Can you post your circuit and what your expected result.

There are two AC sources, one has a default of 120 Vrms and the other is 1Vpk.  In the Select Component dialog under the Sources group, Power Sources family have the 120Vrms and in the Signal Voltage Sources you will find the 1Vp source.  When you are running an AC or Single frequency analysis, double click on the source you placed on the schematic and you will see a field AC analysis magnitude, this magnitude is use in the AC and single frequency analysis.  The default for both sources is 1V, so if you Vin is other than 1V, you need to chagne this field.

[MAGNOTRAN]

First of all thanks very much for your reply.

Here are the requested info:

[MAGNOTRAN]

[MAGNOTRAN]

My hand calculated results:

For this example, I get:

Z = 400 – j300

Z, mag = 500, phase = -36.86

I, mag = 0.04, phase = 36.86

VR, mag = 16 , phase = 36.86

VL, mag = 52, phase = 126.86

VC, mag = 64, phase = -53.14

The Multisim magnitude values are all off by factor of 20. Phase values are all correct.

These hand calculated values are correct sin sqrt( R ^ 2 + (VC – VL ) ^ 2) = 20 which is the source voltage.

[Branch_Support-NIC]

Can you post the Multisim file, I like to see how you set everything up.

[MAGNOTRAN]

Just in case the circuit diagram is not very clear.

All components are in series:

AC source: 20 Vp at 795.77 hz or 5000 rad/sec, phase = 0

R = 400 Ohm

L = 260 mH

C = 125 nF

[MAGNOTRAN]

I am new here and not sure how to attach the file as I do not see an attach link for attaching a file.

[Branch_Support-NIC]

After you click the Reply button, you should see a Browse button click on it navigate to the location where you saved the file.  Some file extension is not allowed to be attached on NI forum; if the file you want to attach won't load you have to zip it.

[MAGNOTRAN]

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