power factor measurement help needed

[halflimit]

my project is to make power factor meter,
my approach is to find out the zero crossing of both Current and Voltage,
find out the time difference and then calculate the angle

can anyone tell me which zero crossing detector i should use,
i am using 8051 mc,

other ideas are highly appreciated

 

[goldsmith]

Hello Dear halflimit
As we know the differential of each function at max , will be zero , so , you can design it simply . you can convert your sine wave to an square wave simply , and then you can take differential from that , thus the out put will be spikes .
Good luck
Goldsmith

 

[gpkpwe]

hi halflimit..... power factor measurement is so easy in pic16f877a..... use current transformer and potential transformer to take voltage and current sine wave ..example... from 230v to 5v sine wave we can get . using zero crossing detector u can take the time period of both current and voltage..using transistor give the pulse to pic... then do the calculation in pic ..show the result in lcd... problem solved

 

[goldsmith]

By the way , i forgot to say , that you can use AD633 to achieve , watt meter or Var meter , or PF meter .

 

[FvM]

By measuring I-V phase angle, you're only aware of displacement power factor while distortion power factor is at least ignored. At worst case, current distortion can even fake a wrong displacement angle.

 

[dr pepper]

I'm having that issue here at work, our pf equipment is old and doesnt accurately measure pf, distortion is the cause of the problem, we have nearly a megawatt of heating elements controlled by phase angle thyristor modules.
I think a better pf meter and a big line reactor is required.
Pf measurement can be tricky depending on your load.