power factor

Power Factor Correction

Power Factor –The Hidden Cause of High Energy Bills?

Poor power factor at your facility may be contributing to unnecessarily-high energy costs. Your electricity bill should indicate that your meter measures either kW or kVA. These are not the same! If you are billed based on kW, then poor power factor is probably not an economic concern for your business, unless your energy delivery company charges a (poor) power factor penalty. Typically, penalties are assessed if power factor measured at the meter is less than 95%. Alternatively, if you are billed based on measured kVA, then poor power factor translates directly into high energy costs.

How Does This Work?

Many electrical devices such as motors and even some lighting products can contribute to overall poor power factor. As an example, a self-ballasted compact fluorescent light bulb consumes 15W (true power) and operates at 120V. However, this particular light bulb is labeled 0.26A. 120V X 0.26A = 31.2 VA, (apparent power), which is far higher than the 15W. This is an indication that this product has a very poor 48% power factor. The electric utility company must deliver the apparent power noted above in order to meet the light bulb's needs. If the electric meter is recording energy usage as kW, then the utility company is getting short changed by the difference between the apparent power supplied, and the true power shown on the meter. In certain energy markets, this shortfall is allocated to all energy users, but in other markets, the shortfall is allocated directly to the individual facilities that have poor power factor in the form of a hefty penalty.

Lighting

To be fair to fluorescent lighting technologies, quality fluorescent ballasts for general lighting in offices and industrial settings can have a near perfect power factor, and these “good” types of lighting systems are far more common in commercial and industrial settings than the consumer-grade product cited above. Besides consumer-grade compact fluorescent lighting, other lighting systems that may contribute to poor power factor include magnetic, (or core and coil), fluorescent, metal halide, high pressure sodium and other high intensity discharge ballasts.

Motors

In an industrial setting, electric motors contribute to poor overall power factor more than any other facility system. Power factor for motors with similar specifications can vary widely, and power factor for two identical motors will vary widely depending on how far they are physically located from the electrical panel, and how they are loaded.

Correcting Poor Power Factor

Adding capacitance, (industrial size capacitors), to counter reactance, (reactive power), can correct poor power factor on a facility-wide basis. In the above example of the light bulb, the reactive power is 23.2 VAR. Adding a 18.3 VA capacitor to the circuit will bring the power factor to greater than 95%. When these calculations are applied on a facility wide basis to determine a correctly-sized capacitor system, the end result will be dramatically-reduced energy expenses when a power factor penalty exists or when an electric meter records kVA instead of kW. Contact your Good Energy representative today arrange an engineering study to determine how much capacitance should be added to your facility's electrical system to correct poor power factor.