What effect does a capacitor have on line current on the source side of the capacitor?

A capacitor affects line current on the source side by providing reactive power, which can lead to a decrease in the overall current drawn from the source. When a capacitor is connected to an AC system, it stores energy in the form of an electric field, which allows it to release this energy back into the circuit at a later time. This reactive power means that the capacitor can supply additional energy to the circuit without drawing additional current from the source.

In a scenario where a capacitor is introduced into an existing circuit, it reduces the real power current that needs to be supplied by the source. This happens because the capacitor essentially "lags" the current, causing the power factor to improve and therefore requiring less current to deliver the same amount of useful power. By decreasing the overall current that flows into the circuit from the source, the capacitor helps to reduce line losses and improve system efficiency.

This effect is particularly important in power distribution systems, where capacitors are often used for power factor correction. By decreasing the line current from the source, the total current drawn is minimized, which is beneficial for both the efficiency of the system and reducing stress on the infrastructure.