From: sno@opelc.com   
      
   Thank you for reminding/showing me how much I have forgotten....   
      
   have fun....sno   
      
      
      
   On 1/26/2012 9:05 PM, Mho wrote:   
   > There is another factor using perfect sine waves.   
   >   
   > What if the voltage and current are not present at the same time?   
   >   
   > This is called "power factor". Now the power (perfect sine waves for   
   > both) becomes E x I x cos(theta).   
   > e.g. if you put a voltage across an inductive load and the phase angle   
   > lag of the current becomes 30 degrees to the voltage (as a reference)   
   > the power factor is 0.866025.   
   >   
   > VA is straight ExI   
   >   
   > RVA (reactive power) is E x I x sin(theta)   
   >   
   > TMI? Onlt power really matters. The rest is wasted in inefficiencies etc...   
   >   
   > For dirty waveforms it can get nuts.   
   >   
   >   
   > 0.707 refers to the RMS value. This is the Square Root, of the Mean, of   
   > the Squares.   
   > Take a sine wave and dissect it at say 4 regular points. If the peak is   
   > 100 then the points we have are   
   > 0 deg. = cos(0) x 100V = 0V   
   > 90 deg. = cos(90) x 100V = 100V   
   > 180 deg. = cos(180) x 100V = 0V   
   > 270 deg. = cos(270) x 100V = -100V   
   >   
   > Square all the values for 10K + 0 + 10K + 0   
   >   
   > Take the mean 20K / 4 = 5,000   
   >   
   > Take the SRoot(5,000) = 70.71067 Vac RMS.. Look familiar?   
   >   
   >   
   >   
   > Back at ya'...have fun!   
   > -------------   
   >   
   > "sno" wrote in message   
   > news:4f1fa1d0$0$2611$892e0abb@auth.newsreader.octanews.com...   
   >   
   > When dealing with true sine wave...the equivalent dc voltage is peak ac   
   > voltage times .707 (not sure of the number, is what I remember) has been   
   > years since I studied and used these formulas..do not remember if normal   
   > ac voltmeter reads average or the equivalent voltage..you are correct is   
   > more complicated if voltage/current varies...I spent years teaching   
   > basic and advanced electronic...which does not mean much..since was many   
   > years ago.....   
   >   
   > have fun....sno   
   >   
      
      
   --   
   Correct Scientific Terminology:   
   Hypothesis - a guess as to why or how something occurs   
   Theory - a hypothesis that has been checked by enough experiments   
     to be generally assumed to be true.   
   Law - a hypothesis that has been checked by enough experiments   
     in enough different ways that it is assumed to be truer then a theory.   
   Note: nothing is proven in science, things are assumed to be true.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)