All posts in Power Quality International

Bank of America is one of the world’s largest financial institutions, serving individual consumers, small- and middle-market businesses and large corporations with a full range of banking, investing, asset management and other financial and risk management products and services. As part of its $20 billion commitment to support the growth of environmentally sustainable businesses that address global climate change, Bank of America has committed $1.4 billion to meet the U.S. Green Building Council’s LEED® (Leadership in Energy and Environmental Design) certification requirements in all new construction of office facilities and banking centers and invested $1.5 billion to renovate environmentally progressive office towers in Charlotte, N.C. and New York City.


The 30-story Charlotte corporate headquarters building, vintage mid-1970’s, had twenty two (22) low- voltage distribution transformers serving the building that were nearing end of life. Like most Fortune 500 companies experiencing a growing dependence on information technology and integrating controls, as well as supporting expanding data processing and call centers, all served by an aging power system, the decision was made to renovate this 24/7 corporate facility’s power system. The goal was to achieve 100% compatibility of the connected loads with the power system. After extensive building surveys, PQI was challenged to present the case to utilize PQI Harmonic Mitigating Transformers versus K-rated Transformers as part of the renovation strategy of the building’s power system.


To reduce nonlinear load-generated ‘penalty losses’ in the distribution system, increase system and load energy efficiency, improve system power factor, and reduce voltage distortion at the 480-volt loads, The PQI Power System Optimization Plan was implemented resulting in a new low voltage distribution system comprised of the replacement of twenty two 45 kVA harmonic mitigating transformers, in a 24-pulse configuration.


100% compatibility of the connected loads with the power system of the building was achieved. Under the connected loads in the new configuration and based on the cost of power, the annual financial reduction of power exceeded $170,000. This renovation of the bank’s corporate headquarters in Charlotte also resulted in dramatically reducing the building’s carbon footprint while achieving LEED Gold™ certification, the first renovation project in North Carolina to achieve this distinction.


HP is a technology company that operates in more than 170 countries around the world. HP explores how technology and services can help people and companies address their problems and challenges, and realize their possibilities, aspirations and dreams. HP applies new thinking and ideas to create more simple, valuable and trusted experiences with technology, continuously improving the way its customers live and work.


Hewlett-Packard unveiled one of the most ambitious data center consolidation projects ever, which consolidated 85 data centers worldwide into six larger centers located in three U.S. cities – Atlanta, Houston and Austin. However, distributing the power in these mission critical facilities required ultra energy efficiency that was unmatched in the industry.


PQI was selected as the ultra energy efficient transformer source for numerous 500 kVA transformers. These transformers were custom made for HP and were beyond any industry standard for efficiency in the industry.


The consolidation will help HP reduce its IT spending by approximately $1 billion in the coming years. The facilities also will serve as a showcase for HP Adaptive Infrastructure products and services. The data centers will provide HP with more dependable, simplified operations. This effort will enable faster delivery of new technologies, services and information and provide room for growth and improved business continuity, while significantly reducing costs. And HP will enjoy the highest power quality in the industry as a result of the PQI ultra energy efficient transformers.

FedEx called on Power Quality International, Inc. for assistance. They were experiencing dangerous airframe-to-ground arcing, when supplying their aircraft from their hanger’s 400Hz electrical power system. Inside a hanger is considered a potentially explosive environment. Arcing is an unacceptable hazard.

Arcing results when zero-sequence harmonic currents, flowing through the zero-sequence impedance of the aircraft’s metallic airframe, generate zero-sequence harmonic voltages (Eh = Ih x ZH). Any grounding of the airframe will cause arcing. Arcing occurred when the hangar’s grounded hydraulic lines or static grounding cable come into contact with the aircraft. The zero- sequence current, which flows on the airframe, is generated by:

  1. Unbalanced loading in the three-phase, fourwire
  2. Single-phase nonlinear loads, which generate unbalanced positive- and negative- sequence harmonic currents, and
  3. Single-phase, nonlinear loads, which generate third-order, zero-sequence harmonic

In order to eliminate arcing, zero-sequence currents and arc voltage must be eliminated.

The measured arc voltage was 4.1 volts, sufficient to cause continuous arcing. The predominant arc frequency is 1200Hz, the 400Hz system’s third harmonic.


PQI was able to eliminate arc voltage with the application of a 400Hz IoFilter™ – Zero-Sequence Harmonic Filter.

The filter also improved the system’s power quality by:

    • Reducing peak phase current,
    • Reducing average phase current,
    • Reducing transformer losses,
    • Reducing system losses,
    • Reducing total harmonic distortion,
    • Improving power factor,
    • Improving phase current balance, and
    • Improving phase voltage balance.

The zero-sequence current at the aircraft was reduced by 95%. At this level, there is not enough current to sustain an arc should arc voltage increase. In addition, the arc voltage was reduced from 4.1 volts to less than 0.1 volts, which is a reduction of 97.6%. The reduction of zero-sequence current and airframe to ground voltage can be accompanied by applying an ultra low zero-sequence impedance at the load or aircraft end of the three-phase, four-wire radial feeder circuit. The zero sequence filter will shunt all zero-sequence currents, at its point of connection, in proportion to the zero-sequence impedance of the source and the filter.

The Bellagio Resort & Casino, Las Vegas, is part of the MGM Mirage Group, one of the largest hotel & casino operations. Their family of resorts includes Aria, Circus Circus, City Center, Excalibur, Luxor, Mandalay Bay, MGM Grand, Monte Carlo, New York- New York and The Mirage.


PQI was asked to investigate the cause of several serious operational problems at the Bellagio Hotel & Casino in Las Vegas, Nevada. These problems included corruption of data in the computer and slot machine networks, and poor video quality at the surveillance system monitors. PQI uncovered two significant power quality issues, which were the cause of these network and picture quality problems. The issues included high levels of voltage distortion and neutral- to-ground voltage at these sensitive electronic loads. Power system and load incompatibility problems are common when the loads are nonlinear. PQI was next asked to find a solution and prepare a detailed proposal.


PQI proposed and was authorized to supply zero-sequence harmonic filters for all branch circuit sub- panels and harmonic mitigating transformers for all five targeted sub-systems. The application of these devices was guaranteed to resolve the identified operational and system incompatibility problems.


With annual savings of approximately $241,381 and an installed cost of $363,956, the payback was 1.5 years and the rate-of-return was 66%. If harmonic mitigation had been included in the original design, payback would have been achieved in less than 6 months.

POWER QUALITY INTERNATIONAL is the industry leader in the development, design and manufacturing of harmonic mitigating and energy-efficient transformer technologies. With a passion for solving problems and helping customers achieve power quality and energy efficiency, PQI delivers cost-effective solutions that ensure power quality and energy efficiency for the life of their customers facilities.

Wynn Resorts Limited is a developer and operator of high-end hotels and casinos. The company’s first project, Wynn Las Vegas, opened on April 28, 2005. The Encore, an extension to Wynn Las Vegas, broke ground on April 28, 2006 – the first anniversary of the opening of Wynn Las Vegas.

Wynn Macau, the company’s first project in The Peoples Republic of China, started construction on June 28, 2004. It opened September 5, 2006. The Encore at Wynn Macau, the company’s second tower, opened on April 21, 2010.


On January 15, 2010, PQI received a report regarding a severe harmonic problem at the Wynn Macau Encore tower from JBA Consulting Engineers, who had been retained to evaluate performance issues on the hotel’s electrical distribution systems. During the initial commissioning, JBA observed flickering lights in the guest rooms and unusual humming and vibration in the six distribution panels that supply the hotel’s Diamond Feature. The Diamond Feature is a unique lighting display located on the exterior concave facade of the Encore tower. This display extends from the seventh floor to the fiftieth floor. The feature includes approximately 70,000 randomly controlled, dimmable cold cathode fluorescent lamps.

The average total harmonic distortion of current (THDI) at the lamps’ local controllers was measured at 191%, while THDI at the six distribution panels was between 114% and 156%. High current distortion was thought to be the likely cause of panel humming and vibration. In an Ohm’s law relationship with the

distribution panel, which is most remote from the main switchgear, was 21%. These are the highest levels of current and voltage distortion ever presented to PQI. True Power Factor (TPF) on the riser supplying the Diamond Feature was measured at 0.68. Based on this information, we anticipated very high harmonic-current related “penalty losses” and very low efficiencies in the distribution system and its loads.

Under this load condition, THDV at the facility’s main switchboard was measured at 19%. This level of baseline voltage distortion was therefore imposed on all other distribution system loads. Since a high percentage of these loads are also nonlinear, THDV is expected to be well above 10% at all other loads. IEEE Standard 519-1992 recommends a limit of 5% THDV at a system’s loads. High voltage distortion was thought to be the likely cause of flickering lights in the guest rooms. In addition to diminishing system and load functionality and reliability, the presence of voltage distortion at the linear loads will result in identical current distortion; that is, %THDI will equal %THDV. In this environment, linear loads produce harmonic currents.


To resolve the observed operational issues, reduce distortion and “penalty losses” and improve power factor, PQI prepared a harmonic mitigation plan with guaranteed outcomes. This plan was presented to JBA Consulting Engineers on January 20, 2010 – five days after receiving their report. JBA sent our mitigation plan to the owner’s representative for approval. To resolve all identified issues, our plan proposed the application of five ultra-efficient harmonic mitigating transformers at the line side of the five distribution panels that supply the Diamond Feature. These Distribution TransFilters™ (filters) were to be used to convert the Diamond Feature’s six-pulse loads to a twenty-four-pulse load at their common 400-volt riser. The filters would also create a separately derived grounded neutral adjacent to each distribution panel and reduce the distribution system’s zero-sequence impedance by approximately 200X. We discovered later that PQI’s proposed solution was one of three presented to the owner’s representative.

The Wynn organization elected to proceed with a solution prepared by Schneider Electric (Square D). Their solution required the application of an active harmonic filter (AHF) at each of the Diamond Feature’s five distribution panels. These devices are designed to analyze a circuit’s harmonic current profile then inject harmonic currents, which are equal in magnitude but 180° out-of-phase, into the circuit. This effectively cancels the load-generated harmonic currents. Unfortunately, the Diamond Feature’s lamp controllers produce a current rise time and duration that was well beyond the AHF’s ability to track or mitigate. This problem actually caused the AHF to increase current and voltage distortion. To increase the currents’ rise time and duration and reduce service.

With these serious issues unresolved, the owner next engaged JBA to undertake harmonic modeling of the affected distribution system. Upon completion of their study, JBA produced a comprehensive report in January 2011, which described the performance of the existing system under nonlinear loading (baseline). Their calculations closely approximated the site measurements taken one year earlier. The report then described the performance of the system with the addition of Schneider Electric’s active harmonic filters and K-Rated distribution transformer.

JBA’s report then detailed anticipated outcomes based on solutions offered by General Electric and PQI. The report concluded that only PQI’s proposed solution would reduce voltage distortion at the main switchboard to an acceptable level, the key requirement with respect to the flickering light problem, and reduce harmonic current loading at the five distribution panels. Based on this report, PQI was authorized to proceed.


Before installing the five Distribution TransFilters™, PQI took a full set of power and harmonic measurements at the main switchboard that supplies the Diamond Feature and the Encore tower’s guest rooms most affected by voltage distortion, the five Diamond Feature lighting control panels and the five distribution panels that supply them. Upon completion, the proposed filters were installed, the lighting feature was reenergized and a new complete set of measurements were taken. Before and after measurements revealed the following outcomes at the main switchboard: harmonic current magnitudes, Schneider next applied a one-to-one, K-Rated distribution transformer at the line end of the riser. This caused a further increase in voltage distortion. The result was an unacceptable failure rate of the dimmable cold cathode fluorescent lamps, which cost $10.00 US each. As a result, the AHFs and K-Rated transformer were removed from

Before Mitigation | After Mitigation | Reduction

19% THDV 4.4% THDV 77%

This reduction met the IEEE Standard 519 recommendation and resolved the “flickering lights” problem.

The initial measurements revealed a significant but previously unreported problem, that is, high neutral- to-ground voltage at the five distribution panels and lighting controls. Before and after measurements revealed the following average outcome:

Before Mitigation | After Mitigation | Reduction

13.1V 2.5V 81%

This reduction met the Information Technology Industry Council (ITIC) recommendation and will likely reduce lighting controller and/or lamp failures.

With the conversion of the Diamond Feature lighting loads from six-pulse to twenty-four-pulse, current distortion and RMS current were reduced, while power factor was improved, on the 400-volt riser:

Before Mitigation | After Mitigation | Reduction

120% THDI 72.6% THDI 39.5%

0.680 PF 0.979 PF

High neutral currents, which exceeded the phase currents, were totally eliminated on the riser. The efficiency improvement from the reduction in the distribution system’s load losses has resulted in a very attractive financial benefit.

A more complete analysis of these operational and power quality issues, their resolution and the financial outcome are discussed in a paper authored by JBA Consulting Engineers and Power Quality International.