A facility can draw more current than its useful load seems to justify, and the reason is power factor. Motors and transformers pull reactive power that does no work but still loads the cables, transformers, and utility bill. Power factor is the number that captures how much of the drawn power is actually useful. This guide explains what power factor is, the relationship between real, reactive, and apparent power, why a poor power factor costs money, and how it is corrected on oil and gas sites.
Power Factor in one line: Power factor is the ratio of real power (kW, the power that does useful work) to apparent power (kVA, the total power drawn), a number between 0 and 1. It measures how effectively current is converted into useful work. Inductive loads like motors draw reactive power (kVAR) that lowers power factor, increasing current and losses without doing extra work.
AC power splits into three related quantities. Real power (kilowatts, kW) does actual work - turning a shaft, producing heat. Reactive power (kilovolt-amperes reactive, kVAR) shuttles energy back and forth to build the magnetic fields that motors and transformers need; it does no net work but still requires current to flow. Apparent power (kilovolt-amperes, kVA) is the total the system must supply, combining the two.
These relate through the power triangle: apparent power is the vector sum of real and reactive power, and power factor equals real power divided by apparent power, or the cosine of the angle between them. A power factor of 1.0 (unity) means all the drawn power is real. A lagging power factor of, say, 0.8 means the system is carrying 25 percent more current than the useful load alone would require, because of the reactive component from inductive loads.
Poor power factor forces more current through the same conductors, transformers, and switchgear to deliver a given real load. That extra current means higher resistive losses, more voltage drop, and equipment that is effectively derated - a transformer sized in kVA reaches its limit sooner when much of that kVA is reactive. Correcting power factor frees up capacity in existing infrastructure without new hardware.
There is also a direct financial driver: many utilities meter reactive power or apply a power-factor penalty, billing customers whose power factor falls below a threshold (often around 0.9 or 0.95). A facility with many large motors can pay a meaningful surcharge purely for reactive power it never turns into work. Improving power factor removes that penalty and reduces demand charges tied to apparent power.
Oil and gas facilities are motor-heavy - pumps, compressors, fans, and drives are largely inductive, so their natural power factor lags. Correction adds capacitors, which supply reactive power locally so the upstream system does not have to. A fixed or automatically switched capacitor bank, sized to the reactive load and often controlled by a power-factor controller that switches steps as load changes, raises the power factor toward unity. Care is needed with VFDs and harmonics, where detuned or filtered banks may be required.
Metering devices and power monitors measure power factor, kW, kVAR, and kVA continuously. A cloud SCADA such as Merobix can read those power-quality tags over Modbus or DNP3, so operators can trend power factor across sites, verify that correction equipment is working, and catch a drifting power factor before it turns into a utility penalty or an overloaded transformer.
A power factor close to 1.0 (unity) is ideal, and utilities typically want customers above about 0.9 to 0.95 to avoid penalties. A power factor of 0.8 means the system carries roughly 25 percent more current than the useful load requires. Correction equipment is used to raise a lagging power factor back toward unity.
Inductive loads cause it - motors, transformers, and drives draw reactive power (kVAR) to build magnetic fields, and that reactive component lowers power factor. Lightly loaded motors are especially poor. Because oil and gas facilities run many large motors, their natural power factor lags and usually needs correction with capacitors.
Usually by adding capacitors, which supply reactive power locally so the upstream supply does not have to carry it. A fixed or automatically switched capacitor bank, sized to the reactive load, raises power factor toward unity. Where VFDs and harmonics are present, detuned or filtered banks are used to avoid resonance problems.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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