Transformer Power Factor 1

[Mondy]

Dear experts

How do I go about calculating what the power factor is of a 1500VA transformer off-load and at full load (resistive)

Also how would I go about calculating the values of PFC capacitors connected in parallel with the primary to improve the power factor if it is bad?

Many thanks
Mondy

 

[jghrist]

stevenal,

The C57.90 formula for regulation uses the "American" definition of regulation. (|V_{no load}|-|V_{full load}|)/|V_{full load}|. You can verify this with your results where:

V_{full load} = 100% @0°
I = 100% @0°
R = 3.76%
X = 3.81%
For resistive load,
|V_{no load}| = sqrt(|V_{full load} + I·R)² + (I·X)²) = 103.83%
(|V_{no load}|-|V_{full load}|)/|V_{full load}| = 3.83%