PQI clients and customers benefit from over fifty years of engineering and technical hands-on field experience. With the exception of Antarctica, we’ve completed major assignments on every continent.

With its technical and manufacturing ‘know how’, PQI was first to develop and commercialize a number of leading-edge power magnetic technologies and products. These accomplishments, some of which are listed here, provide cost-effective solutions to various technical, power quality and energy efficiency problems.

2015 First to offer three Transformer Efficiencies that Exceed DOE 2016 efficiency requirements, under the linear or nonlinear load environments for which they were designed.

PQI’s Standard Z3 Efficiency Rating exceeds the US DOE 2016 requirements. Optional Z3+ and Z4 (US DOE CSL 4) efficiencies are available when their additional cost produced an attractive payback and ROI.

2015 – First to receive a UL Certificate of Compliance per UL1562 for our Harmonic Mitigating, Medium Voltage, Cast-Coil Power Transformers. Both CSA and UL have approved our manufacturing facility as a Qualified Product Evaluation and Test Facility.

Measurements and test data generated during product evaluation is now accepted by both CSA and UL for product approval.

Power TransFilters™ have also received Seismic Pre-Certification in accordance with the requirements of the International Building Code 2012 (IBC2012), the California Building Code 2013 (CAB2013) and the National building Code of Canada 2010 (NBC2010). In addition, the transformers specifically met the requirements of OSHPD (Office of Statewide Health Planning and Development of California).

2003 – First to develop a Transformer Excitation & Impedance Loss Measurement Instrument, based on the earlier Voltage & Current Differential, Loss Measurement Method.

Transformer Performance Analyzer™ limits the efficiency calculation error to ±0.033%, when measuring a transformer’s excitation and impedance losses under linear or any nonlinear load condition.

2003 – First to use a sophisticated computer program that is in compliance with IEEE Std. C57. 110-1998, that allows our engineers to recalculate any transformer’s linear losses and efficiency into its nonlinear losses and efficiency, which is based on a specific harmonic current profile.

The PQI Calculator™ will compare the performance of any two transformers and calculate a payback and return-on-investment.

The PQI Calculator TM
Project Sample
  1. 0
To compare the performance of a 75 kVA, K-13
  1. 0
K13 DY0
Distribution TransFilter, under K-13 loading.
  1. 0
Date August 20, 2008 8.0
Linear Eff. at 35% of TX Rated kVA 95.00%
DY0 kVA Rating 75.0 Losses (kW) vs. kVA Rating (pu)
Zero-Sequence Harmonic Flux Cancellation Yes/No Yes 1.000
Linear Eff. at 35% of TX Rated kVA 98.65%
Installation [ if replaced before end-of-life ] $1,000.00
Air Conditioning Requirement

Months/Year [ direct or indirect ]

12 Efficiency (pu) vs. kVA Rating (pu)
Days/Year for Segment 261 261 104 365
Calculation of Penalty Losses

Actual kW Losses for K13









Actual kW Losses for DY0 0.823 0.460 0.306 0.546
Difference in kW K13 DY0 2.753 1.460 0.923 1.768
Annual Energy Savings, including A/C Costs $1,753.88 $930.03 $492.77 $3,176.68
Calculation of Financial Benefits

Annual Savings, including A/C Costs, when using DY0

$3,176.68 / year
Payback on Incremental Cost [ substitution ]

Return-on-Investment (ROI) on Incremental Cost [ substitution ]

4.7 months

253.1 %

Payback on Installed Cost [ before end-of-life replacement ]

Return-on-Investment (ROI) on Installed Cost [ before end-of-life replacement ]

2.1 years

48.1 %

Reduction in kWh over 25 years of operation 387,298.12 kWh saved
Summary of Environmental Benefits

Annual Reductions per EPA Formula

11.44 tons of CO2 90 kgs of SO2

33,695.74 kgs of coal 39 kgs of Nox

2 acres of trees 2 homes heated 2 fewer cars on the road each year



2003 – First to develop a Technology Demonstration Vehicle that demonstrates all harmonic related ‘power quality’ issues, and compares the accuracy of the Power-In – Power-Out, Loss Measurement Method and the Voltage & Current Differential, Loss Measurement Method.

2001 – First complete line of Harmonic Filtering Transformers that exceed EPA – Energy Star® linear load efficiency requirements under nonlinear load conditions.

PQI HarMitigator™ products, which include harmonic mitigating power, distribution and drive isolation transformers, are approximately 2% more efficient than any competing harmonic mitigating transformers and up to 15% more efficient than typical conventional or K-Rated transformers, under severe nonlinear loading.

2001 – First computed program that will calculate a solution for harmonic current, ‘penalty loss’ and power cost reductions, and system performance and power quality improvement.

The PQI Solution™ includes the consulting services of a professional engineer specialist who will provide guidance in the selection and application of PQI’s technically advanced, ultra- efficient e-Rated® products. This service is offered on a no-fee-basis to system designers. If our recommendations are fully implemented, PQI will guarantee compliance with the power quality requirements of IEEE Std 519-1992 – IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems. The proper selection of products and application of our engineered solution will result in the most cost-effective optimization of system and load efficiency and compatibility. Implementation of our recommendations will also result in an increase in our standard warranty from 10 years to 20 years.

2000 – First electromagnetic Zero-Sequence Harmonic Filter that shunts zero-sequence harmonic currents at the load-end of a branch circuit.

Mini-Z™ filters provide an alternative to de-rating conventional distribution transformers, applying K-Rated distribution transformers, increasing ‘shared’ neutral conductors or configuring branch circuits with separate neutral conductors, in an environment that is rich with zero-sequence harmonic currents.

1996 – First commercial sale of Medium Voltage Class Sub-Cycle Voltage Regulator Transformers for application in a utility’s distribution system.

PQI TransRegulator™ products mitigate the voltage sags that result from fault clearing events on a utility’s transmission and distribution systems.

1991 – First complete line of Harmonic Filters and Harmonic Mitigating Transformers that shunt or cancel zero-sequence harmonic currents and/or cancel positive- and negative-sequence harmonic currents.

PQI HarMitigator™ products, which include harmonic mitigating power, distribution and drive isolation transformers, reactors and filters, provide the means to implement The PQI Solution.

1990 – First to develop and apply Harmonic Mitigating Transformers that shunt zero-sequence harmonic currents with ultra-low zero-sequence impedance windings and cancel positive- and negative-sequence harmonic currents within their secondary windings.

Distribution TransFilters™ provide an alternative to de-rated conventional distribution transformers or applying K-Rated distribution transformers. These ultra-efficient transformers meet their published efficiency in the nonlinear environment for which they’re designed.

1986 – First electromagnetic Zero-Sequence Harmonic Filters that shunt zero-sequence harmonic currents from a three-phase, four-wire sub-system.

I0Filter™ provide an alternative to de-rating conventional distribution transformers, applying K-Rated distribution transformers or increasing feeder circuits’ neutral conductors, in an environment that is rich with zero-sequence harmonic currents.

1983 – First to develop a Three-Phase Power Harmonic Analyzer that measures harmonic currents, voltage magnitudes and phase angles, up to the 50th harmonic, then calculates total harmonic distortion of current and voltage, harmonic power flow for each individual harmonic, system impedance at each harmonic frequency, kVT or IT products for each harmonic and Telephone Interference Factor. This project led to the development of the first Fluke, Model 41 Harmonic Analyzers.

1982 – First ‘on-line Partial Discharge Analyzers that monitor the condition of stator winding insulation systems in hydroelectric generators.

PDA-H® technology remains the ‘world standard’ for failure avoidance and maintenance optimization. This technology is now used on turbo-alternators and medium voltage class motors.

1965 The founder of PQI, while an employee of Ontario Hydro-Electric Power Commission, developed the first Three-Phase Transformer Ratiometer. This instrument measured the true turns-ratio of any single- or three-phase power transformer, distribution transformer or voltage transformer with an accuracy of 1 turn in a 100,000 (±0.001%) or a current transformer, with an accuracy of 1 turn in 10,000 (±0.01%). The instrument was also capable of detecting internal impedance changes, such as loose connections, burned tap-changer contacts or turn- to-turn insulation deterioration.

The Transformer Ratiometer™, after 50 years of service, remains the most accurate and reliable field instrument for confirming a transformer’s turn-to-turn windings ratio.