Under what condition is the Power Factor considered to be unity?

The power factor is considered to be unity when voltage and current rise and fall together, which indicates that the phase difference between them is zero. This means that the electrical power being consumed is at its maximum efficiency, as all the supplied power is being used effectively, with no reactive power present. When the power factor is unity, it signifies that the load is purely resistive, and all the energy supplied is converted into useful work without any losses associated with inductive or capacitive effects.

In contrast, when the voltage is higher than the current, there is no direct relation indicating unity power factor. Similarly, if there’s a time delay in the current flow compared to the voltage, this suggests a phase difference that typically results in a power factor less than one, indicating inefficiency in power usage. Lastly, a constant voltage does not necessarily imply a unity power factor, as the relationship between voltage and current must still fulfill the condition where they fluctuate in synchrony, which is not guaranteed by voltage being constant alone.