Power Factor Across Transformer

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My second guess is OP's load is overcompensated and has leading load power factor. His transformer's inductance compensates leading load power factor and improves line side power factor.
 
Sahib said:
My second guess is OP's load is overcompensated and has leading load power factor. His transformer's inductance compensates leading load power factor and improves line side power factor.
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No mention of PFC other than yours. We need confirmation PFC is involved and the actual data to proceed down that path.
 
Jraef said:
What? Do you mean to imply that a utility might try to manipulate their revenue stream by carefully planning where they place their meters? Unheard of!

:lol:
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:lol:

Not the sacred utility
they are so responsive and so quick to share information
 
There is no PFC in the substation. And the load is mostly inductive, it's a large industrial plant (40 MVA total, with about 27 coming from on-site generation, so we're buying around 13 MVA).

If the transformer is a delta primary, wye secondary, could it be the phase transformation that's causing this? These types of transformers have a 30 degree phase change correct?
 
adamscb said:
There is no PFC in the substation. And the load is mostly inductive, it's a large industrial plant (40 MVA total, with about 27 coming from on-site generation, so we're buying around 13 MVA).

If the transformer is a delta primary, wye secondary, could it be the phase transformation that's causing this? These types of transformers have a 30 degree phase change correct?
Click to expand...

The phase change in a transformer should equally affect both voltage and current and so should have no net effect on power factor.
 
adamscb said:
There is no PFC in the substation. And the load is mostly inductive, it's a large industrial plant (40 MVA total, with about 27 coming from on-site generation, so we're buying around 13 MVA).
Click to expand...
The POCO power factor metering is on load side. Right? If so, it is only to be ascertained whether they are recording a leading power factor. If yes, it answers your OP query. If no, it is likely defective metering.
 
It is not important if 69 kV or 13.8 kV is towards the utility, indeed.
Let's say 13.8 kV it is the supply side. The rated current of 40 MVA is 1673.5 A but actually only 13 MVA is required so only 543.9 A. If the transformer impedance voltage is 11% then X=13.8^/40*11/100=0.5237 ohm [since X/R >10 we may neglect R].
Then the reactive power across the transformer is 3* 543.9^2*0.5237=464.75 kVA.
However, a no-load current of 3% [50 A] considered entirely reactive will require SQRT(3)*50*13.8=1200 kVAR.
The load power factor -let's say=0.9 then Qload=sqrt(1-0.9^2)*13000=5666.6 kVAR.
The total supplied reactive power will be 5666.6+1200+464.75=7331.3 kVA.
sin(psi)=7331.3/13000=0.4716
pf=cos(psi)=sqrt(1-0.4716^2)=0.8258[8.24% less] viewed from utility side.
 
Engineer

Engineer

I was wondering if your meter and the utility meter KW, KVA, KAR readings agree. You have already stated the PF does not agree. If these other values do not agree (taking into consideration the transformer losses which should not be significant) you more than likely have a meter setup problem. Does you meter provide you with a phasor diagram? This diagram would help you to determine if the phase orientation of the voltage and currents are correct. If the orientation of the voltages and currents are incorrect the meter will read incorrectly and could possibly give you bad PF readings.
 
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