When the transformer is unloaded, there is no current in the secondary winding, and most of the primary current is used for excitation. The excitation current is reactive current, so the power factor is very low.
Specific methods:
1, and the power factor of transformer is the ratio of active power to apparent power. The no-load active power of transformer is the no-load loss of transformer, which is basically fixed. In order to improve the power factor, the method of reducing the apparent power can be adopted.
2. Increasing the number of transformer windings can reduce the excitation current and apparent power, thus improving the no-load power factor.