Reactive power causes heat loss, or energy loss, in electrical installations. Since reactive power and the associated reactive current are additional incidental factors to the actual power and, therefore, increase the total current, energy losses due to heat development also increase.
Transport of reactive current causes heat losses
Current is required for transporting energy to a load. This current flows through a conductor. Ideally, this current will not encounter any resistance on the way to its final destination. In practice, however, conductors always have resistance.
When a current encounters resistance, it is converted into the most basic form of energy: heat. This means that heat losses occur everywhere in these conductors. The higher the current and/or the higher the resistance, the greater the unwanted energy losses and heat development. In addition, the resistance of conductors increases as temperature rises.
Heat loss caused by reactive power reduces the efficiency of the installation and may even result in continuity problems.
Heat loss, or energy loss, is only one of the consequences of reactive power. Other effects of reactive power include loss of capacity in the installation, tripping of fuses and protections and overheating of cables and distributors.