Calculating Percent Regulation From Transformer Parameters
Calculating Percent Regulation From Transformer Parameters
(OP)
If I know the percent impedance and load loss (kW) for a given three phase transformer, how can I calculate the percent regulation as shown on the test report? I'm getting fairly close, but there's still an obvious oversight I'm not recognizing.
I'm calculating percent real impedance by taking the load losses divided by the base MVA rating of the transformer and multiplying by 100 to get percent. Is this correct for a three phase transformer?
I'm then taking the per unit nominal voltage of 1.0 and subtracting (real per unit impedance * per unit real current) and (reactive per unit impedance * per unit reactive current).
Thanks
I'm calculating percent real impedance by taking the load losses divided by the base MVA rating of the transformer and multiplying by 100 to get percent. Is this correct for a three phase transformer?
I'm then taking the per unit nominal voltage of 1.0 and subtracting (real per unit impedance * per unit real current) and (reactive per unit impedance * per unit reactive current).
Thanks






RE: Calculating Percent Regulation From Transformer Parameters
RE: Calculating Percent Regulation From Transformer Parameters
That is the same voltage drop going from 0-100% load.
RE: Calculating Percent Regulation From Transformer Parameters
RE: Calculating Percent Regulation From Transformer Parameters
RE: Calculating Percent Regulation From Transformer Parameters
% Voltage regulation at full load = %R cos phi + %Xsinphi where cos phi is the PF of the load
RE: Calculating Percent Regulation From Transformer Parameters
Regulation is defined as the change in output (secondary) voltage which occurs when the load is
reduced from rated kVA to zero, with the applied (primary) voltage maintained constant and is
expressed as a percentage of the full-load secondary voltage.
Example:
Z = 7.94%
R = 51.192/12000 (load loss divided by rating)
R = 0.427 %
X := sqrt(Z² − R²)
X = 7.929 %
pf := 80% φ := acos(pf ) φ = 36.87deg
Formula from "ABB Transformer Tests, Their Purpose and Importance":
Reg = R⋅cos (φ) + X⋅sin(φ) + [(X⋅cos (φ) − R⋅sin(φ)]²/2
Reg = 5.283649%