The power factor is, simply put, the ratio of working power to apparent power, or demand power. The power factor is an expression of energy efficiency, with a higher percentage indicating more efficient energy consumption and a lower percentage indicating less efficient energy consumption. To calculate the power factor, divide the working power (kW) by the apparent power (kVA). While an efficiency of 100% may not be realistic, there are a few things that affect it, improving the power factor requires a good strategy.
What is the ideal power factor?
A low power factor means you are not using the energy you pay for efficiently. Lower power factors require more apparent power (kVA) to produce working power (kW). A higher power factor is better than a lower one because it means you are using energy more effectively. A common target number for the power factor is 95%. Check with your utility company what threshold they use. Many utilities charge customers if they have a low power factor.
Measuring and managing energy consumption
By the measure energy and power quality, you will get a feel for the rhythm of your installation and learn how to keep your plant running smoothly and efficiently. Strategic power management is an important way to reduce your energy consumption and your energy bill. One reason to improve your power factor is to reduce or even eliminate fines and surcharges from your utility company.
To do that, you need to know where your energy is going each month. First of all, you need to measure and record energy data from your equipment and systems. The type of instrument you need to do this depends on your facility and needs. A multifunctional tool can calculate energy losses and record high-resolution three-phase voltage and current waveforms, while another instrument can provide direct status data of mains power quality. It is important to know the level of harmonics in your power. A THD (Total Harmonic Distortion) measurement can help you figure out whether filtering is needed. And remember that a utility can only affect voltage quality. They can only require approved loads to be connected and are not responsible for the current flowing as a result of the customer's installation.
Steps to a better power factor
Motor inductance and harmonic currents are two common factors that contribute to poor power factor. To improve power factor, determine the root cause of poor power factor.
When dealing with inductive current, adding power factor correction capacitors (energy storage devices) to your plant's power distribution system is a commonly used solution. Power factor correction capacitors require regular inspection and recommended preventive maintenance, but under normal conditions they will operate trouble-free for years.
If harmonics cause the low power factor, cost-effective passive LC filtering (inductor-capacitor) is the solution.
For more complex situations, active filtering is needed. This type of filtering compensates for reactive currents, harmonic currents and unbalanced currents.
A common mistake is to use capacitors to limit harmonic currents. A capacitor behaves like a short circuit for higher harmonics. Because of the internal resistance, the capacitor will heat up and have a drastically shorter lifespan as the internal electrolyte evaporates.
