# per unit conversion

Discussion in 'General Electronics Chat' started by almotions, Nov 4, 2009.

1. ### almotions Thread Starter Active Member

Feb 6, 2009
46
0
Hi all,
assuming a three-phase supply (25k Vrms phase-phase) supplying a three-phase load. I connected a voltage and current measurement block having a base voltage of (25k Vrms phase-phase) and base power of
(1M VA 3 phase). With the pu voltage and current measurements into a active and reactive power measurement block,the output of the power measurement block must be multiplied by a gain of 2/3 in order to have the correct active and reactive power measurement.My question is why 2/3?
All these are simulated in SIMULINK/MATLAB.Thanks..

Regards,
alvin

2. ### mik3 Senior Member

Feb 4, 2008
4,846
63
I think is the ratio of the base value to the maximum value.

3. ### lmartinez Active Member

Mar 8, 2009
224
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Provide a oneline diagram of the power system being analyzed? It will visually help us provide more detail assistance to your question.........

4. ### Duane P Wetick Active Member

Apr 23, 2009
408
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If each phase feeds 2 loads, and the loads are then split between the other two phases, then the system is considered balanced. (assuming the load VA's are the same.) You don't have to worry about the vectored relationships if all are equal, just simple math will suffice.

Cheers, DPW

Last edited: Nov 8, 2009

Feb 6, 2009
46
0