Complex Imaginary Module 1 Problem 1

[Muath]

Hi Everyone,

The question below is from complex imaginary

based on Wildi book the output voltage should be Vdc = 1.35V_LL



So my the answer should be 125*1.732*1.35 = 292.3V??

Can anyone please clarify?

 

[BirdGrave]

The problem asks for the peak (or maximum voltage), Vmax.  You're given Vrms, the variable EEs are accustomed to working with. 

Vrms (or any rms value of a continuous set of numbers from time T1 to T2) is defined as: 

The formula that relates the two is Vmax = sqrt(2)*Vrms.  So in this case Vmax = sqrt(2) * 125 = 177 V.

 

[Drewism]

It's a trick question. They want to know the PEAK voltage not the DC voltage. You solved for the DC voltage. The peak voltage is what @BirdGrave has said. 125Vrms * root(2) = 177V.

Careful when reading those problems.

 

[Muath]

Thanks BirdGrave, Drewism

So if the question asks for the peak output voltage, should it be equal to the peak of the line of line voltage = sqrt(2) x sqrt(3) x 125 ???

 

[rmsg]

Thanks BirdGrave, Drewism

So if the question asks for the peak output voltage, should it be equal to the peak of the line of line voltage = sqrt(2) x sqrt(3) x 125 ???

The output at AB is not going to be 3 phase, it is going to be either one of the single phase, so yes then the peak to peak of that one of the single phase will be 125Vrms * root(2) = 177V.