wiserguy
Newbie level 2
Power-Factor Issue
I have designed a Power/Energy meter that uses the cirrus CS5463 part. It works a treat - I think. The problem started when I used a Xitron $17K Power Analyser to check its calibration.
The reference load was a heat gun - half wave rectified element and DC motor - yes a crappy load I agree but people use these things and might want to know the Power-Factor - hopefully we can help them..........
The data for realW, apparentVA, ARMS & PF for the Xitron versus my unit are
1) 878W, 1249VA, 5.094A, 0.7029
2) 873W, 957VA, 3.908A, 0.912
My Tektronix TrueRMS says 3.8883ARMS - unless it is set to AC+DCRMS then it says 5.08ARMS
My question is which answer is more/only correct? The xitron uses shunts not current transformer so its not a saturation issue. Both answers are feasible and yield the correct true power from the sum of the VA and PF - but I am sure both cant be correct ?
I always assumed VRMS x IRMS was VA I dont remember learning anything about DC offset except for saturation of tranformers - which are not involved (ok to a miniscule amount) here.
FYI if I turn off the HPF in the Cirrus part I get the same results as the Xitron - but is that the right answer ? We are being supplied AC and measuring the AC energy warts and all should I need to turn on the DC pass option.
Thanking you in advance for any help offered.
I have designed a Power/Energy meter that uses the cirrus CS5463 part. It works a treat - I think. The problem started when I used a Xitron $17K Power Analyser to check its calibration.
The reference load was a heat gun - half wave rectified element and DC motor - yes a crappy load I agree but people use these things and might want to know the Power-Factor - hopefully we can help them..........
The data for realW, apparentVA, ARMS & PF for the Xitron versus my unit are
1) 878W, 1249VA, 5.094A, 0.7029
2) 873W, 957VA, 3.908A, 0.912
My Tektronix TrueRMS says 3.8883ARMS - unless it is set to AC+DCRMS then it says 5.08ARMS
My question is which answer is more/only correct? The xitron uses shunts not current transformer so its not a saturation issue. Both answers are feasible and yield the correct true power from the sum of the VA and PF - but I am sure both cant be correct ?
I always assumed VRMS x IRMS was VA I dont remember learning anything about DC offset except for saturation of tranformers - which are not involved (ok to a miniscule amount) here.
FYI if I turn off the HPF in the Cirrus part I get the same results as the Xitron - but is that the right answer ? We are being supplied AC and measuring the AC energy warts and all should I need to turn on the DC pass option.
Thanking you in advance for any help offered.
