The power factor of a transformer is always lagging because the primary winding of the transformer draws magnetizing current, which lags the applied voltage. This magnetizing current creates the necessary magnetic field in the core, and since it is inductive in nature, it causes the overall power factor to lag.
The power factor is always lagging in most AC circuits because inductive loads such as motors, transformers, and inductors are common.
These inductive loads cause the current to lag behind the voltage due to the energy storage in their magnetic fields.
Power systems generally operate at a lagging power factor because they predominantly supply inductive loads like motors and transformers. These loads draw current that lags the voltage, which is a natural characteristic of inductive components. Operating at a lagging power factor is typical and expected in these systems.
To correct a lagging power factor, capacitors are added to the circuit.
These capacitors provide leading reactive power, which counteracts the lagging reactive power caused by inductive loads. By balancing the reactive power in the system, the overall power factor is improved, reducing losses and increasing efficiency.
To know if the power factor (PF) is leading or lagging, observe the phase relationship between the current and voltage. If the current lags behind the voltage, the power factor is lagging. If the current leads the voltage, the power factor is leading.
This can be determined using a power factor meter or by analyzing the waveforms with an oscilloscope.
In a transformer, “lagging” refers to the phase difference where the current in the primary winding lags behind the applied voltage. This is due to the inductive nature of the transformer’s windings, which require magnetizing current to establish the magnetic field in the core, resulting in a lagging power factor.