The power factor is associated with load. If you have no load then any reading is meaningless.

without load, power factor shown by meter is ambiguous or mall functioning,

regards

divyesh patel

Regardless of no load, the power source could be supplying power to other parallel (reactive) loads via other transformers, so you could have current lagging voltage upstream which would give you pf = .75 at your secondary transformer with no load.

Are you doing short circuit tests on your trans?

If ur PF is 0.75 on no load ur PF is extrmely good.

I assume the measured power factor is on the primary side of the transformer. Regardless of load on the secondary side, the transformer needs a magnetization current (no-load current) for its magnetic circuit. The resulting power factor may be even lower in such case. When you load the transformer, the active component (R) of the current, dependent on the load in the secondary, will increase, while the magnetization component (X) will increase only by probably 20% (depending on how the transformer was designed - Hysteresis curve of material).

As a consequence, the power factor will increase when approaching full load.

Power factor on the secondary side is a direct function of the type of applied load (resistive, inductive, capacitive). N/A at no-load since there is no current.