English 
Teknik Bilgiler
Reactive Power Compensation System
Reactive Power Compensation System
Power Factor Definition
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.
In a 3 phase supply, kW is being consumed ((Volts x Amps x √3 x Power Factor) / 1000). While the supplied electricity is kVA (Volts x Amps x √3x / 1000). Suppliers of the electricity have to supply extra to make up for the loss caused by poor power factor. When the power factor falls below a set figure, the electricity supplier either charge a premium on the kW being consumed, or, charge for the whole supply as kVA.
Therefore power factor 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.
Power Factor Correction – Reactive Power Compensation
A poor power factor can be the result of either a significant phase difference between the voltage and current at the load terminals, or it can be due to a high harmonic content or distorted/discontinuous current waveform.
The ideal power factor would be unity (or 1) on theory however power factor of 0.95 to 0.98 is satisfactory for electricity suppliers. The actual fact in reality is that the power factor is reduced by highly inductive loads to 0.80 or less. This induction is caused by equipment such as induction motors, power transformers, and fluorescent lighting ballasts and welder or induction furnace, etc.
Reactive Power Compensation is applied to circuits which include induction motors as a means of reducing the inductive component of the current and thereby reduce the losses in the supply. There should be no effect on the operation of the motor itself.
Power factor correction is achieved by the addition of capacitors in parallel with the connected motor circuits and can be applied at the starter, or applied at the switchboard or distribution panel. The resulting capacitive current is leading current and is used to cancel the lagging inductive current flowing from the supply.
In other words, by supplying the reactive demand through capacitors in the consumption center the reactive power is being compensated. In this way, the necessity reactive power will be supplied by compensation of system (by capacitor banks) instead of importing by electricity network.
As a result of power factor correction; saving up to %20 and improvement in the quality of the energy can be obtained. In addition to this, it contributes to extend the life and decrease the heat level of devices and equipment and have saving in the cost of cabling by decreasing the cable section needed in the system.
Harmonic Filter Reactor (Passive Harmonic Filter)
Harmonics are a distortion of the normal electrical current waveform, mainly generated by
non-linear loads. These non-linear power creates significant distortion in the electrical current and voltage wave shape. This harmonic distortion is measured as total harmonic distortion (THD).
The distortion travels back into the power source and can affect other equipment connected to the same source. It causes problems like equipment overheating, motor failures, malfunctioning of equipment, capacitor failure, increase in internal energy losses, inaccurate power metering, fires in wiring and distribution systems, false tripping of branch circuit breakers, and reducement in system efficiency.
Compensation with harmonic filter reactor (passive harmonic filter) is needed if there are harmonic sources in the system from SMPS (switch-mode power supplies) equipment such as static AC/DC power transformers, rectifiers, inverters, arc furnaces and electrolysis units, DC motors, AC speed control units, soft starters, frequency transformers, UPS, PCs, lighting with electronic ballats, photocopiers, personal computers, laser printers, fax machines and other control systems with wave change and phase adjustment. Harmonic filter reactors prevent the possibility of resonance.
Compensation Panel With Thyristor Switches
Compensation panels with thyristor switches are used for complex industrial processes in which there are equipment sensitive to voltage fluctuations, industrial robots, elevators, cranes, spot or groove welding machines, variable speed motor drives. This type of compensation panels are useful to balance the reactive power and solve problems arising from poor quality energy. By nature, thyristor switches should be used together with reactors in the compensation panels.
