Electrical loads such as motors can cause electrical systems to be very inductive, which results in very ‘lagging power factor’ i.e. wastage of energy. The simple solution to maintain the power factor in required range is to connect or disconnect the power factor correction capacitors. Manual switching is just impossible for rapidly fluctuating loads and hence an automatic control system is required which continuously monitors the power factor and make appropriate corrections to maintain it within the required range.
Power factor is the ratio between the KW and the KVA drawn by an electrical load where the KW is the actual load power and the KVA is the apparent load power. It is a measure of how effectively the current is being converted into useful work output and more particularly is a good indicator of the effect of the load current on the efficiency of the supply system.
All current flow causes losses both in the supply and distribution system. A load with a power factor of 1.0 results in the most efficient loading of the supply. A load with a power factor of, say, 0.8, results in much higher losses in the supply system and a higher bill for the consumer. A comparatively small improvement in power factor can bring about a significant reduction in losses since losses are proportional to the square of the current.
Most of the electrical loads are inductive in nature resulting in severely lagging power factor. The most practical and economical solution to improve the power factor(PF) is to provide reactive compensation by installing power capacitors of suitable rating at strategic locations. But this has to be operated manually and which may result in the over voltages, damage of the electrical equipment saturation of transformers etc. PF correction is more important in electrical distribution systems. For accomplishing the same low voltage(LV) capacitors are being extensively used both as fixed capacitor banks and in Automatic Power Factor Correction (APFC) Panels