Composite wood products plant

Composite Wood Products Plant

“In the six years following the application of the Eaton solution, the plant has recorded savings of nearly $20,000 per month, with total savings of more than $240,000 per year.”

Background
Poor power utilization results in low power factor. Certain industries such as Forestry Products are known to have poor power utilization and low power factor.

Power factor is the ratio of working power (kW) to apparent power (kVA). It measures how effectively electrical power is being used. A high power factor signals efficient utilization of electrical power, while a low power factor indicates poor utilization of electrical power. Utility companies constantly track this metric and often penalize companies with low power factor as an incentive to implement solutions that lead to more effective energy utilization—which results in lessened demand on the utility.

In this case, the local utility charged a penalty to a wood processing plant when power factor dropped below 0.90. As a result, this Southeastern U.S. Forestry Products processor became subject to thousands of dollars in power factor penalties per month from the utility.

Challenge
Operational demand at the wood processing plant varied significantly throughout the day, leading to vast fluctuations in the demand placed on electrical equipment. Motor loads were required to switch from lightly loaded to fully loaded countless times throughout any given shift. The change in loading caused power factor levels to drop well below the 0.90 threshold at which the utility penalizes its large industrial customers for poor power factor.

The resulting poor power utilization led to the plant suffering power factor penalty charges from the utility averaging more than $20,000 per month. Plant management estimated the elimination of power factor penalties would result in savings of approximately $250,000 each year. This opportunity represented a very attractive return if it could be achieved. However, the plant knew it needed to collaborate with a company possessing power quality expertise to make its vision a reality.

Solution
To develop a solution, the plant sought out the expertise of the local Eaton Power Quality Team in North Carolina. The team of engineers and power quality solution experts were able to facilitate the quick development of an effective, customized solution.

After the team carefully reviewed the plant’s loads, historical data and monthly utility bills, a power factor correction (PFC) capacitor bank solution was developed that would raise the power factor to acceptable utility levels. Additional calculations were performed to specifically avoid harmonic resonance, which would interfere with the reliable operation of variable frequency drives and other electronic equipment.

Analysis of plant data led to the Eaton team recommending one custom de-tuned, automatically switched, medium voltage PFC capacitor bank and five automatically switched, low voltage de-tuned PFC capacitor banks of various ratings that were then installed to raise the power factor level while avoiding harmonic resonance.

The automatic PFC bank systems were designed so that they will automatically switch capacitors in and out of the electrical system in order to maintain a predetermined level of power factor. Additionally, a fully automated controller in each automatic PFC bank would provide metering with real-time power and energy monitoring for enhanced system oversight.

Results
After applying the Eaton solution, the plant increased its average power factor level to a point avoiding utility penalties. The average increase from 0.70 to 0.91 exceeded the utilities 0.90 average threshold for penalties. In addition to eliminating penalties, the installation has proven to be a reliable solution remaining online without incident.

In the six years following the application of the Eaton solution, the plant has recorded savings of nearly $20,000 per month, with total savings of more than $240,000 per year. The plant was able to recoup the cost of the Eaton PFC system, and achieve a complete return on investment in less than 12 months.