G. N. C. Ferguson, B.Tech., MI & SS, M.IEEE

Abstract - The effect of single-phase, non- linear loads, as sources of positive, negative and third order, zero sequence harmonic currents in low voltage electrical distribution systems, is discussed. Various traditional methods for dealing with these harmonic currents are outlined and their shortcomings identified. Alternative methods, which provide harmonic current reduction, and power quality improvement, are presented. Results of the application of alternative devices in typical environments are given.

A paper reprint from the InterNational Electrical Testing Association (NETA) Annual Technical Conference,
March 19, 1996, St. Louis, MO,

COSTS AND BENEFITS OF HARMONIC CURRENT REDUCTION
FOR SWITCH-MODE POWER SUPPLIES
IN A COMMERCIAL OFFICE BUILDING

Thomas Key and Jih-Sheng Lai

Abstract – Harmonic currents generated by modern office equipment cause power system heating and add to user power bills. By looking at the power-related losses in a specific electrical system – representing a commercial building – energy costs are quantified. The analysis shows that building wiring losses related to powering nonlinear electronic load equipment may be more than double the losses for linear load equipment. Current-related power losses such as I2R, proximity of conductors, and transformer winding eddy currents I2h2) are considered. The cost of these losses is compared to the cost of reducing harmonics in the equipment design. Results show that an active-type harmonic-elimination circuit, built into the common electronic equipment switch-mode-power supply, is cost-effective based on energy loss considerations alone.

A paper reprint from IEEE IAS Annual Meeting, October 1995, Orlando, Florida

Thomas Key and Jih-Sheng Lai

GRAPHIC SUMMARY
by
Power Quality International, Inc.

Introduction - This summary graphically displays selected information contained in the attached IEEE paper entitled: ‘Cost and Benefits of Harmonic Current Reduction for Switch-Mode Power Supplies in a Commercial Office Building’, authored by Thomas Key and Jih-Sheng Lai.

The paper’s Case Study is based on typical 60kW commercial office building loads, supplied by a conventional ‘unmitigated’ electrical distribution system, for 12 hours per day, 365 days per year, at a power cost of $0.10 per kWh.

The graphs, included in this summary, extrapolate the selected information in order to demonstrate the cost and benefits for electrical distribution systems with higher ratings and heavier loads.

In producing these graphs, it is understood that each electrical distribution system is unique and the results will vary. However, the graphs can be adjusted for variations in the electrical distribution system’s configuration, its components, loads and the cost-of-power.

Neither the paper nor this summary discusses the cost benefits associated with power quality improvement, increased productivity or the potential for capital cost reduction for a new distribution system, any one of which may be greater than the costs and benefits discussed here.

All contents Copyright 1999, Power Quality International, Inc., All Rights Reserved

Gregory N.C. Ferguson, B.Tech., MI & SS, M.IEEE

Abstract - Harmonic currents, generated by single and three-phase non-linear electronic loads, cause ‘penalty’ losses throughout the electrical distribution system. These losses result in apparatus overheating, higher air conditioning costs and higher power costs. Harmonic currents effectively de-rate every element of an existing distribution system and, if accommodated by over-sizing and K-Rating, add substantially to the capital cost of a new or upgraded system. The magnitude of the various costs will be examined and alternative harmonic mitigating system designs will be presented.

A paper reprint from World Energy Engineering Congress, October 2001, Atlanta, Georgia

Gregory N.C. Ferguson, President, Power Quality International, Inc.

Abstract - The electrical distribution systems, which support hospitals’ administrative offices, now supply primarily non-linear electronic loads. These loads typically include fluorescent lighting, security systems, facility monitoring systems, servers, computers, printers, telephones, facsimile machines and virtually all office peripherals. Like other modern facilities, hospitals’ heating, ventilation and air-conditioning systems and elevators also utilize electronic motor drives. However, in addition to these typical facility loads, hospitals’ electrical distribution systems must also supply critical electronic medical equipment.

All non-linear electronic loads generate positive- and negative-sequence harmonic currents. Single-phase non-linear electronic loads, which are connected phase–neutral in a three-phase, four-wire distribution system, also generate zero-sequence harmonic currents. These load-generated harmonic currents are injected into the hospitals’ electrical distribution systems.

Business Briefing: Hospital Engineering & Facilities Management 2003

Gregory N.C. Ferguson, B.Tech., MI & SS, M.IEEE

Abstract – Harmonic currents, generated by non-linear electronic loads, produce ‘penalty losses’ in every element of an electrical distribution system. These harmonic-related losses reduce system efficiency, cause apparatus overheating, and increase power and air conditioning costs.[1]

Harmonic currents effectively de-rate existing systems and, when accommodated, add substantially to the capital cost of new systems which must be de-rated or K-Rated.

The magnitude of typical ‘penalty losses’ and increased operating costs will be evaluated. The capital cost of conventional and harmonic mitigating system designs will be discussed, and the financial benefits will be calculated.

Reprint from the International Power Quality Conference, October 2002, Singapore