Can both be true New meter reads of volt, amps and power but the values don't compute

D

Dan Kissel

Member
Location
st louis, mo
I just installed a meter on the 480 to 240 delta step down transformer - 750 kva . The phasor diagram appears to be correct, but the power (KW) does not make sense. At the time to the picture I had only LED lighting and it was .97 PF.
Where is the problem.

240 vac - 400-500 amps, .97 PF but only 9.2 KW
 

Attachments

  • PM8000 Phase diagam reducee size.JPG
    PM8000 Phase diagam reducee size.JPG
    791.9 KB · Views: 17
  • PM8000 Power consumption reduced size.JPG
    PM8000 Power consumption reduced size.JPG
    1.1 MB · Views: 17
Did you go through the entire setup procedure? Are there settings for the CT ratios?
 
Yes - Even if a setting for the CT ratio is wrong, wouldn't the meter's calculation use the current as displayed and calculate a KW. The KW should be closer to 125 - 207 KW depending on the which current is used or KW per phase is added up.

I pretty sure that the meter is set for a Delta, but I don't think that would make a difference.
 
I'm probably missing something obvious, but for a delta system you are measuring L-L voltages, but line currents.

Wouldn't you expect a 30° phase difference if the loads were near balanced and near unity power factor?
 
The power display says "Demand". That is normally an average power consumption over a fixed time period, like 30 minutes. Is there a display for instantaneous power?
 
You must log in or register to reply here.
Top