The power utilities in most industrialised nations charge users a penalty when their power system’s power factor drops below a certain level, usually below 0.90. This power factor surcharge covers the electric utility’s cost of supplying your power system with additional reactive power. 

In South Africa, no “fines” are imposed as yet, although Eskom intends to introduce fines in the near future. 

Some South African municipalities (i.e. City Power) do charge for excessive reactive power consumed, which is a form of “fine”. City Power charges for all reactive power consumed below a power factor of 0.96!

Electricity has until recently been a cheap commodity in South Africa (and Southern Africa in general). The payback period of an investment in power factor correction has therefore been fairly unattractive. The recent tariff hikes have significantly reduced the payback periods and will continue to do so in the short to medium term.

Power factor correction equipment dates back to the 19th century and is based on proven scientific concepts.

There is no financial benefit under these circumstances BUT, it could free up capacity on your supply, allowing you to add more equipment and in so doing increase production or avoid relocation to different premises with a larger power supply.

Power factor correction reduces the total current drawn from an electrical distribution network (which affects systems such as the power stations, distribution grid and supply transformers). In so doing, the heat or transmission losses incurred on these systems are reduced. Power factor correction therefore only has a minor impact on your carbon footprint.

The reactive power of a capacitor, as shown on its data plate, is always indicated at a specific voltage. If the voltage of an installation is lower than the rated capacitor voltage, then the output if the capacitor is negatively affected.

For example: a capacitor of 10 kVAr rated at 440V will only provide 8.3kVAr if the system voltage is only 400V! 

This is an important factor which must be taken into consideration when determining the reactive compensation requirements of an electrical installation.

If you connect the correct value of capacitors in the supply to an induction motor, you will reduce the current flow from the supply to the point where the capacitors are connected. If you measure the current in the supply between the capacitors and the motor, you will find that the current does not change. The current into the motor is independent of the connection of the capacitors. The efficiency of the motor is unchanged.

In most instances, not. The motor losses are not changed so the temperature rise of the motor remains the same. However, if you install a suitably rated capacitor directly onto the motor, you will reduce the current flowing through the supply cable and in so doing, reduce the volt drop on the cable. This in turn can result in a reduction of the total current drawn by the motor, which will reduce the heat (Watt) losses (=I²R) of the supply cable.

Manufacturers of diesel-electric generator sets usually indicate the maximum output of their equipment at a specific power factor, usually 0.8.

This means that if you purchased a 1000kVA generator set, you actually bought an 800kW system. Installing power factor correction would in theory allow you to increase the output of the set to 1000kW. The alternator will be able to cope with this load, but the diesel engine will not.

Another potential problem is that under conditions of significant and sudden load reductions (for example a major fault in the system), the power factor correction system will not respond fast enough to reduce its reactive power output to match the reduced requirements. The excess reactive power generated by the power factor correction panel has nowhere to go and the system voltage will increase dramatically. This usually results in significant damage to the generator, the power factor correction panel and the associated electrical distribution system. Generator suppliers usually clearly indicated in their warranty conditions that power factor correction which is in operation with the generator will render their warranty null and void.