I have new friend assigned in the power substation asking my help,since i have no idea on electrical i post this problem to this furom.

he said,in the substation there is primary metering,primary voltage is 34.5KV line to line,CT is 1200:5, PT is 34.5KV/sq.root of 3, .115KV/sq.root of 3. so, meaning, what is the reading on the meter should be multiplied by the ratio in the CT and PT,right?
but they did not multiply the ratio of CT & PT to the energy consumption?
Is the energy consumption totally correct or not?

No one else has replied yet, so I will have a go.

From what I understand you are saying the CT's are 1200:5 and PT's 34.5k:115.

Standard 3 ph power formula is:
P=sqrt(3)*E*I*Cos(theta)

Assuming balanced 3 ph load and power factor=1, then your power should be:

P=sqrt(3)*(34.5k/115)*E2*(1200/5)*I2

where E2 and I2 are measured on the secondary side of your PT & CT respectively.

So, as an example, if you measured 115V across your PT, and 5A on your CT you would have:

P=1.73*300*115*240*5
P=71.7 MW

This would apply if you are measuring directly on your secondary sides of the CT's/PT's. The installed metering may already do some calculations and take other factors into account.

Thanks for your reply Sir, there is a meter designed for automatically calculate the multiplier of CT & PT? Thanks