What is Compensation? What Does It Do, How Does It Work and Why Is It Necessary?

Compensation is the electrical regulation process performed to balance the reactive power and improve the power factor in electrical facilities. Briefly, the answer to the question of what is compensation is; It is a correction method that allows the system to operate more efficiently by reducing the reactive power drawn by inductive loads from the network. Therefore, compensation is not just a panel or a few capacitors; It is an engineering application directly related to the power quality and energy use of the facility.

At the center of the question of what compensation is for is the power factor. In industrial facilities, commercial buildings and businesses with large electrical loads, a phase difference occurs between current and voltage due to motors, transformers, ballasts and similar inductive loads. This situation causes reactive power to be drawn in addition to active power. Reactive power does not directly convert into work; but it increases current circulation in the transmission and distribution system. The purpose of compensation is to reduce this unnecessary reactive current requirement as much as possible.

When asked why compensation is necessary, it would be incomplete to say that it only reduces the risk of reactive penalties. A well-made compensation system reduces the total current requirement by improving the power factor. When the current decreases, the load on the cable, busbar and transformer decreases; voltage drops and losses can be limited; The existing capacity of the facility can be used more efficiently. In other words, compensation is not only an invoice item but also a matter of technical efficiency.

The basic answer to the question of how compensation works is this: a capacitive reactive power source is added to the system against the delayed reactive power drawn by inductive loads. This job is done with capacitor banks in most applications. Capacitors balance the effect of inductive loads by providing forward-going reactive power. As a result, the total reactive current that the network has to carry decreases and the power factor becomes closer to unity.

It is difficult to evaluate compensation correctly without understanding the concept of power factor. Power factor is one of the key indicators of how efficiently the system works. As the value approaches unity, the unnecessary reactive component carried against the active power decreases. Low power factor indicates that more current is drawn to do the same job and system elements are stressed more. Therefore, compensation is also defined as the application of power factor correction.

Compensation systems are not installed the same way in every facility. The simplest application is fixed compensation. In this method, a capacitor that remains in the circuit for a certain load or a certain section is used. It may be useful in systems whose load characteristics do not change much. However, in facilities with high load fluctuations, more flexible solutions are required. At this point, automatic stage controlled compensation panels come to the fore.

In automatic compensation systems, the power factor relay or APFC relay monitors the instantaneous reactive power need of the facility and activates and deactivates the capacitor stages as needed. Thus, the system shows a dynamic behavior that adapts to load change instead of a fixed solution. The risk of excessive or inadequate compensation is reduced by selecting the appropriate number of stages when the load increases or decreases. For this reason, automatic compensation is a much more suitable approach in businesses with variable load profiles.

Compensation applications may also differ in terms of placement. Local compensation means connecting a capacitor near the load that produces reactive power. In group compensation, similar load groups are handled together. In central compensation, general correction is made at the main distribution panel or the main point of the facility. Which method is more accurate; It is determined according to the load distribution of the facility, cable lengths, process structure and maintenance approach.

When it comes to compensation system, only capacitors should not come to mind. In practice, a compensation panel includes capacitor stages, contactors or switching elements, fuses or switches, power factor relays, current transformer connections, protection elements and, in most applications, discharge resistors. In systems with harmonics, series reactors can also be added. In other words, the compensation panel is a structure where multiple elements work together to ensure safe and controlled reactive power production.

Harmonics are a very critical topic regarding compensation. If the facility has drives, rectifiers, UPS systems, welding machines or similar non-linear loads, an ordinary capacitor bank may not always be the right solution. In such systems, there may be a risk of resonance, overheating and capacitor strain. Therefore, depending on the harmonic level, compensation with detuned reactors or solutions with filters may be required. Harmonic analysis should not be ignored when making a compensation project.

Compensation and harmonic filtering are not the same thing, but in some facilities these two issues should be considered together. Compensation mainly focuses on reactive power balance. Harmonic filtering aims to reduce current and voltage distortions. However, if the compensation system is not designed correctly in harmonic plants, the problem may worsen. For this reason, the load character must be analyzed when choosing compensation, especially in industrial buildings.

Another benefit of compensation is that it helps to use the existing transformer and cable capacity more efficiently. When the reactive current decreases, healthier active power can be transported over the same infrastructure. This may delay the need for new transformer or cable investment in some facilities. Of course, each situation must be evaluated separately, but the positive effect of well-designed compensation on system capacity is often evident.

Incorrect compensation can also pose a risk. Excessive compensation, larger tap selection, wrong current transformer connection, faulty relay setting or capacitor banks selected by ignoring harmonics may cause problems in the system. Therefore, compensation is not just about installing panels; It requires correct engineering calculation, correct stage structure and correct field application.

In summary, compensation; It is a basic electrical engineering practice that improves the power factor by balancing the reactive power in electrical facilities, reduces the unnecessary current carried by the network, and helps the system operate more efficiently. It can be applied as fixed, automatic, local, group or central; In facilities with harmonics, reactor or filter approaches may be required. If compensation need, power factor analysis, panel selection and harmonic effects will be evaluated together in your facility LV/MV/HV project design and consultancy, for general field suitability HV/MV testing, maintenance and repair and relevant technical studies can be planned together for a holistic evaluation of the energy infrastructure.