Hi is anyone able to help me with this question?? draw to scale 3 phasors representing the following voltages, taking e1 as reference phasor e1:= 80 sin ωt volts e2= 60 cos ωt volts e3 = 100 sin (ωt-∏/3) volts I think i understand this part, is it 1 sin wave and 1 cosine wave and 1 lagging sin wave on one 2∏ cycle chart, the part im not sure is it then asks to sum these 3 voltages and express it in the form Em sin (ωt ± θ), i think i can sum the 2 sin waves though i'm unsure, it is the cosine i'm unsure with... is anyone able to help please jim
Consider the phasor e2 cosine as leading the reference e1 sine phasor by 90° [∏/2 radians]. You've typed e2 twice but I assume the 3rd phasor is e3. Phasor e3 lags e1 by ∏/3 [60°]. Use phasor addition to find the sum e1+e2+e3 Then convert the resultant phasor back to the time-domain equivalent.
sorry it was ment to be e3.. edited now... Thanks tnk, does that mean convert into rectangular add the votages then back into polar form.. Am I right about the drawing?? all 3 waves are drawn on one 2∏ cycle.. thanks jim
If you are lucky enough to have a calculator that will do everything (including addition) in polar form then no - you don't have to convert. Otherwise you will probably have to go to rectangular form to do the addition and then back to polar. Are you sure you know what a phasor diagram is? I'm not sure of your meaning in - "all 3 waves on a 2∏ cycle". You may be thinking of the time based waveform diagram - which is not a phasor diagram.
are Phasor diagrams straight lines? or can I draw 2 sin waves and 1 cosine wave superimposed on one graph.. If they are staright lines do i have e1 horizontal mag 80, e2 same origin but vertical mag 60, e3 same origin mag 100 -60° from e1.. is that what is ment by phasor diagram.. or should e2 start from the end of e1, and e3 start from the end of e2.. I know that is what you should do to add the phasors.. thanks jim