Q5Power System - I
Question
Q.5. What will happen when power factor is leading in distribution of power?
Answer
A leading power factor in power distribution causes the receiving-end voltage to rise above the sending-end voltage (voltage boost, opposite of the usual voltage drop with lagging pf), due to the leading reactive current interacting with the line reactance in a way that adds to, rather than subtracts from, the voltage.
In normal (lagging power factor) operation, the reactive component of load current flowing through the line's series reactance produces a voltage drop, causing the receiving-end voltage to be lower than the sending-end voltage. When the power factor is leading (capacitive load, e.g., due to excessive shunt capacitor compensation or lightly loaded, highly capacitive cable circuits), the direction of reactive power flow reverses, and the leading reactive current interacting with the line reactance produces a voltage rise instead of a drop — the receiving-end voltage can actually exceed the sending-end voltage. This condition, called voltage rise or 'negative regulation,' can cause overvoltage stress on equipment and must be carefully managed by controlling the amount of shunt capacitive compensation switched in during light-load periods.