The Importance of Power Factor and Harmonics in Motion Control

For manufacturers, minimizing operating costs to improve overall profitability is always a primary concern. The rise of lean manufacturing concepts have only made this more important, particularly in regard to minimizing energy costs.

Energy costs aren’t only determined by consumption – they’re also determined by the way the utility company bills energy costs, which is where power factor plays a key role. Understanding the power factor at your facility is essential for minimizing energy costs.

What is Power Factor in Motion Control?

Power factor provides a measure of the efficiency of an electrical system at your facility. It is the ratio of real power to apparent power in a system. A low power factor signals excessively high current draw, which requires thicker wires and translates into higher utility costs.

True power factor consists of two different measurements: displacement power factor and total harmonic distortion. For some linear loads, measuring only displacement power provides an accurate measurement, but for all other non-linear loads both measurements are required.

How Do You Calculate Power Factor?

Calculating true power factor can be a complicated process, but it reveals invaluable information into energy use in your facility. At the most basic level, true power factor is found by multiplying displacement power factor and harmonic distortion values.

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Both displacement power factor and harmonic distortion require the measurement of several elements of energy efficiency. As an example, finding power displacement requires understanding of three different factors, including:

• Real power: the power dissipated by the load, in watts. In other words, the power used to create torque in the motor.
• Reactive power: the power stored and discharged by the system in volt-amperes. This is the power that creates magnetic flux in a motor.
• Apparent power: the vector sum of real power and reactive power in volt-amperes.

Displacement power factor and harmonic distortion values are required for a calculation of true power factor and, as shown, you must be able to measure a number of supporting factors to determine these values.

The calculation of true power factor can be complex but taking the time to understand power factor can lead to significant energy savings in your facility.