Power Quality Issues – Part 5 – Reactive Power and Power Factor
As with voltage imbalance, covered in the previous article, reactive power and power factor are not power quality issues in the same sense as harmonics and transients, but are of critical importance, particularly with regards to a facilities electrical energy consumption and efficiency. Julian Grant – General Manager at Chauvin Arnoux UK, looks at the causes and effects of high reactive power and poor power factor, along with solutions to improving them.
In a purely resistive AC circuit, voltage and current waveforms are in phase with each other, changing polarity at the same instant in each cycle and all the power entering the load is consumed by the load. Reactive power exists in an AC circuit when the current and voltage are not in phase. Some electrical equipment used in industrial and commercial buildings requires an amount of reactive power in addition to real power in order to work effectively. These tend to be items with copper windings in them; especially transformers, motors, induction heaters, arc welders and compressors, etc., even fluorescent and LED lighting. In the case of inductive loads, the current lags behind the voltage, however, nowadays various capacitive loads may be encountered which cause the opposite effect, that is for the current to lead the voltage.