Buyer Beware – Using Power Factor Correction and Transient Voltage Surge Suppression to Reduce Energy Costs.
Today’s energy conscious climate has motivated many to do what they can to become more efficient and conserve energy and money. Unfortunately this same climate has prompted others to take advantage of unsuspecting consumers’ wishes to save energy and reduce expenses.
Companies that tout power factor improvement (kVAR correction) and transient voltage suppression are a good example of this bad trend. Lately we are seeing more and more of these companies cropping up and feel it is time to set the record straight.
First, transient voltage surge suppression (TVSS) plays a valuable role in improving power quality to protect sensitive equipment inside a facility. However, TVSS does not save energy. TVSS’s are only active a tiny fraction of a second to protect against voltage surges which only last for less than a millisecond. To actually reduce energy consumption the TVSS would need to actually cut power consumption for an extended period of time which is not what they are designed to do. Again, TVSS is important to protect sensitive electrical equipment but buyers should avoid vendors promising, or even guaranteeing, that they will reduce energy consumption.
Now what about vendors who claim that improving power factor will save 15% or 20% or 30% of energy consumption and corresponding cost? This one is a little trickier.
For residential applications, power factor does nothing to save energy because the typical home already has an average power factor of about 0.97 which is almost the perfect power factor of 1 or unity. In addition, the device (called a capacitor) is placed at the main circuit breaker. According to IEEE 188.8.131.52 capacitors must be situated at or near the respective inductive loads to reduce power system losses by reducing heat and distribution losses known as I2R losses.
So what about commercial and industrial facilities using power factor correction to reduce energy costs? It is perfectly appropriate for a company that is incurring penalties or a kVA billing structure from the utility company to improve the facility’s overall power factor by employing a capacitor bank at the main service entrance or individual capacitors at or near the respective motor loads. Doing so will eliminate the power factor penalties and/or reduce the kVA demand charges on the utility bill which can save significant money and provide a significant ROI on the investment.
But what about power factor correction reducing kWh consumption? IEEE also tells us that I2R losses only account for 2 to 5% of the total load in a facility. Simple math tells us that it would be against the laws of physics to get the 15% to 30% energy reduction claimed by some vendors. Think about it. Even if your facility had 5% distribution losses and you could correct 100% of the problem via power factor correction at every load (which can’t be done) you would still only save 5% at the most. No where near the claims of some capacitor vendors and manufacturers.
All that said, power factor correction when done properly will eliminate utility penalties and kVA demand charges, improve facility power quality, increase electrical system capacity, and save a little energy when applied to the appropriate motor loads.
So make an investment in transient voltage surge suppression and power factor correction when appropriate and necessary. But caveat emptor!