Specialists in Power Management Solutions, Power Metering, Power Quality Metering, Power Quality analyses, Power factor Correction on LV and HV, HV protection equipment, HV protection Maintenance.
Power Factor correction equipment usually pays for itself within 12 months of the initial purchase and continues saving indefinitely. It therefore stands to reason that more significant savings can be anticipated with the ever-increasing escalating costs of electricity in the future.
All modern industries utilize electrical power in some or other form. Two basic categories of loads are encountered in alternating current (AC) networks. These are Resistive and Inductive Loads.
Technoserve also offer specialised Control Panels, Standby Generator sets, Transformers, reconditioned H.V. Switch gear as well as H.V. Power Factor Correction equipment. All equipment used is of the highest standards. Our further speciality involves refurbishing of existing Power Factor systems to our uncompromising standards. We also undertake harmonic surveys as and when required.
RESISTIVE LOADS These are load devices containing only resistance e.g. incandescent lamps, heaters, soldering irons, ovens, geysers, etc. The current drawn from the Supply is directly converted into heat or light. Since the voltage is assumed to be constant, the actual Power (kW) being used is identical to the Apparent Power (kVA) being drawn from the line. The Power Factor is therefore Unity or 1. In these purely resistive circuits, the current and voltage sinewave peaks occur simultaneously and are said to be "In Phase".
INDUCTIVE LOADS This encompasses all equipment utilizing an electrical winding, wound in various ways around an iron core, embodying electro-magnetic fields and fed by alternating current (AC) e.g. electric motors, transformers, welding equipment, reactors etc, generate a voltage which is more or less in opposition with the supply voltage and generally out of step or phase with it. The current drawn from the supply is made up of two separate kinds of current, namely power producing current and magnetizing current. Therefore, the current flowing in an AC circuit (unless corrected) is generally larger than is necessary to supply the power being expended by the plant.
The power factor of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit and is a dimensionless number between 0 and 1.
Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power.
In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor.
Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.
The simplest way to control the harmonic current is to use a filter: it is possible to design a filter that passes current only at line frequency (e.g. 50Hz). This filter reduces the harmonic current, which means that the non-linear device now looks like a linear load.
At this point the power factor can be brought to near unity, using capacitors or inductors as required. This filter requires large-value high-current inductors, however, which are bulky and expensive.
A passive PFC requires an inductor larger than the inductor in an active PFC, but costs less. This is a simple way of correcting the nonlinearity of a load by using capacitor banks.