What happens when the current leads the voltage?

When the current leads the voltage, it typically refers to situations in alternating current (AC) circuits where reactive power is present, often observed in inductive loads. In a purely resistive circuit, the relationship between power, voltage, and current is straightforward: power (P) is equal to the product of voltage (V) and current (I), with the phase angle between them being zero degrees.

However, when the current leads the voltage, this indicates that there is a phase difference, meaning that these two quantities are not perfectly in sync, which usually occurs in inductive circuits. The presence of this phase shift implies that the calculation of real power (the power that actually does work) becomes more complex, as it involves the cosine of the phase angle between voltage and current. This leads to the concept of apparent power (measured in volt-amperes) and reactive power (measured in reactive volt-amperes).

Thus, in scenarios where the current leads the voltage due to reactance, the simple formula P = V x I does not hold true as it does not account for the phase difference. Instead, one must consider the power factor, which can be defined as the cosine of the phase angle. If the system is not