If you measure the current drawn from the supply, you are actually measuring two currents. One current is the work current
that goes into KW, and the other is the reactive current. The two currents are 90 degrees out of phase. The work current is in phase with the supply voltage.
The total current that you measure is the vector sum of the two currents and is equal to the square root of the sum or the squares of the two currents.
You can alter the reactive current without changing the work current. If you increase the reactive current and keep the work current constant, the
resultant measured current will increase. If you reduce the reactive current and keep the work current constant, the resultant current will reduce. If the reactive current is zero, then the resultant current will be equal to the work current.
The power factor is the cosine of the angle between the work current and the resultant current.
Increasing the power factor reduces the reactive current.
Adding power factor
correction to improve the power factor will reduce the reactive current and therefore the resultant current.
The correct formula for KVA = I x V x rt3 / 1000 where I equals the line current, V equals the phase to phase line voltage (i.e. 415 V)
At 300KVA, the current will be 300000 / 415 / 1.732 = 417A
At a power factor of 0.7 and 200KW, the current would be 200000 / 415 / 1.732 / 1.0 = 398A
Meanwhile, if you increase power from 0.7 to 1.0, the current would drop from 398A to 278A
Bulk correction is usually set up to keep the power factor better than 0.95.
The current at 200KW and 0.95 pF would be 200000 / 415 / 1.732 / 0.95 = 292A.