Understanding the differences between active power, reactive power, and apparent power
The different types of power and why they’re important
In today’s world of rising electricity costs coupled with increased electricity demand, businesses are taking strain. Most are looking for ways to optimise electricity use in order to minimise electricity costs. Alpha Power Solutions can help mitigate some of these costs by introducing power factor correction. Before this can be addressed, it is important to understand the differences between active power, reactive power and apparent power.
Active power
Active power, also known as real power, true power or working power, is measured in watts. It is the electricity used to power equipment and machinery at an industrial and commercial level. It is the actual amount of power used, or dissipated, in a circuit. i.e. it is the part of the total power in an alternating current (AC) circuit that is consumed by the equipment to do useful work. In layman’s terms, it is the power used by an AC circuit that powers machinery and equipment used for lighting, heating, pumping, milling, welding and other industrial and commercial activities. It is the actual power consumed by a circuit to perform useful work.
Reactive power
Reactive power, which is measured in VAR (volt-ampere reactive), is the power generated by a capacitor in an AC circuit or the power consumed by a transformer or an AC motor to generate the magnetic field needed for these devices to be able to operate as intended.
Another way of explaining reactive power is that it does not do any direct or useful work like powering machinery and equipment. Instead, it supports the system by helping devices operate correctly by managing the electromagnetic fields they create. It helps control voltage levels and magnetic fields in an electrical system, ensuring that equipment and machinery run smoothly and efficiently.
Apparent power
Apparent power is the power that the grid must deliver to an electrical installation. It is a mathematical (vectorial) combination of real and reactive power. It is the total power that is flowing in an electrical circuit. Another way of explaining it is that it combines reactive power and active (real) power, and it is the product of a circuit’s voltage and current, without reference to phase angle. (Phase angle refers to the number of electrical degrees of lag or lead between the voltage and current waveforms in an alternating current circuit.)
Yet another way of looking at it is that apparent power, measured in volt-amperes, represents the total power observed in a system. It combines both the real power and reactive power, indicating the overall power flow in a circuit.
The beer analogy
Imagine a glass of beer. The thirst-quenching liquid represents active power (kW), while the foam on top represents reactive power (kVAr [Kilovolt-Ampere Reactive]). Although the foam is not a thirst-quenching liquid, it is still part of the beer. The total contents of the glass, both the liquid and the foam, represent apparent power (kVA). Utility companies typically charge industrial and commercial installations for their kWh consumption as well as maximum apparent power drawn. This is why it is important to reduce the reactive power (the foam) your electrical system requires from the utility. The images below depict the differences between reactive, active and apparent power.
Introducing power factor
Power factor (PF) is the ratio of working power (kW) to apparent power (kVA). In other words, PF = kW / kVA. It measures how efficiently the current drawn by the load is being converted into useful output.
A high power factor benefits both the customer and the utility, while a low power factor indicates poor use of electrical power. In other words, power factor is the measure of how effectively the incoming power is used in an electrical system. A high power factor indicates that the power supplied to the electrical system is used effectively. A system with a low power factor doesn’t effectively consume the incoming electric supply and results in losses.
What is power factor correction?
Power factor correction is the process of improving the power factor of an electrical system through the installation of power factor correction equipment. Power factor correction devices help to increase the ratio of active power to apparent power, resulting in the reduction of wasted energy, increased efficiency of the system, and fewer system failures.
Reducing your electricity costs
For businesses with monthly electricity bills of R30 000 or more, Alpha Power Solutions can reduce your monthly electricity costs by between 10% and 25% with customised power factor correction solutions.
We use a power factor formula to calculate the ratio of real power to apparent power by dividing the real power by the apparent power to get a decimal value between 0 and 1. A power factor close to 1 indicates that most of the electrical power supplied to the circuit is being used productively, resulting in a highly efficient system. A power factor below 1 indicates that a portion of the power supplied to an electrical system could be used more effectively by installing power factor correction equipment which generates the reactive power consumed by the system. By optimising the power factor of your installations, we enhance the long-term profitability of your business. You can use our power factor correction calculator to determine your approximate savings.
How we can help you
The power factor correction capacitors installed in our PFC equipment generate the reactive power consumed by your electrical systems. This results in an improvement in the power factor of your electrical supply which, in turn, reduces your electricity costs.
Our case studies
Read about how we saved businesses significant money on their monthly electricity bills, resulting in a huge return on investment:
Contact Alpha Power Solutions today and see how we can significantly reduce your business’ monthly electricity costs.