The Evolution of Partial Discharge Testing in Electrical Equipment

G.C. Stone, Consultant, and Andrea Cavallini, University of BolognaIndustry Topics, Spring 2024 Industry Topics

Partial discharge (PD) testing is routinely used on all types of medium- and high-voltage equipment as a factory quality assurance test for electrical insulation and as a tool to detect deterioration in the electrical insulation of operating equipment. Today, dozens of vendors supply PD instruments, but the first PD tests were made by researchers over a century ago in an …

Neutral and Ground Harmonic-Induced Power Losses and Correction

Howard W. Penrose, MotorDoc LLCIndustry Topics, Winter 2023 Industry Topics

In commercial and industrial power systems, harmonic currents can create a variety of issues, including increased power losses and potential damage to equipment. This article describes the various types of power losses associated with neutral and ground harmonic currents with a focus on resistive losses, transformer losses, and dielectric losses in distribution and power factor correction capacitors, and how these …

Unlocking Reliability: A Guide to Low-Voltage Circuit Breaker Maintenance Testing

Cade Patton, MeggerIndustry Topics, Winter 2023 Industry Topics

Circuit breakers in electrical systems play a critical role in ensuring personnel safety, equipment, and systems reliability. These protective devices are designed to interrupt the flow of electrical current in the event of a fault, preventing potential hazards such as electrical fires and equipment damage.  Low-voltage circuit breakers encompass a range of types, including insulated case circuit breakers (ICCBs)/molded case …

Changes to MV and HV Cable Testing Specifications in ANSI/NETA MTS 2023

Chasen Tedder, PE, Hampton Tedder Technical ServicesFall 2023 Industry Topics, Industry Topics

NETA’s ANSI/NETA standards are some of the most useful publications for the electrical power testing industry. The standards provide guidance to those trying to maintain our fragile electrical infrastructure.  Safety, reliability, and quality were the core principles that drove NETA to pursue the creation of a set of industry standards for electrical power equipment and systems. NETA is accredited by …

Electromechanical Differential Relays Misoperation and Investigation

Alex Rangel, PE, Saber Power Services, LLCFall 2023 Industry Topics, Industry Topics

Transformer differential protection (ANSI 87), which operates on Kirchhoff’s Current Law (KCL),  is one of the most common protection methods for large power transformers. This method was first implemented using electromechanical relays built with instrument transformers and other electrical components to convert secondary currents from amperes to per-unit to apply KCL properly. For a detailed explanation of the operation of …

Interpreting Off-Line PD Test Results of MV Extruded Cables

Shahryar Farhang, MeggerIndustry Topics, Fall 2023 Industry Topics

Medium-voltage (MV) cables serve as the backbone of a distribution system, playing a vital role in ensuring the reliable supply of electricity. However, maintaining this extensive network comes at a significant cost for operators. Off-line partial discharge (PD) testing emerges as a valuable tool in managing operating costs and enhancing the reliability of MV cable systems. By transitioning from traditional …

Predictive Motor Maintenance: Static, Dynamic, and On-Line Testing

Drew Norman, Megger Baker InstrumentsIndustry Topics, Spring 2023 Industry Topics

This article reviews current electrical testing methods and trends in the operational health of electric motors in the context of successful predictive maintenance programs. It explains the concepts of static motor testing — testing a motor that is not running — as well as dynamic motor monitoring, which involves analyzing motors while they are in service or operating within their …

Staying Current with NERC Regulations

Casey Whitt, Shermco Industries, and Maysam Radvar, Power Systems EngineerIndustry Topics, Spring 2023 Industry Topics

In the upcoming years, changes to the existing NERC standards and approved models will be proposed. These changes will impact the synchronous generator (SG) compliance approach and representation. This article outlines proposed changes relevant to generator owners and the impacts on compliance efforts for two such standards: MOD-025 and PRC-019. We also briefly discuss the newly proposed generator model, GENQEC, …

Detecting and Locating On-Line Partial Discharge

Bharat Nandula, QualitrolIndustry Topics, Spring 2023 Industry Topics

Power cables are important assets in transmission networks for the reliable operation of power systems. To prevent catastrophic failures in underground cables and terminations, it is important to know how to leverage the various types of available sensors that can detect PD and locate the source so that appropriate action can be taken to avoid in-service failures. This article answers …

Microgrids in Practice

Mayfield RenewablesIndustry Topics, Winter 2022 Industry Topics

The majority of the U.S. electric grid was built in the early 20th century. It was initially designed for the one-way transfer of electricity from large fossil-fuel power plants directly to consumers. The grid of that era delivered power from rural areas, where power was generated, to cities, where much of it was consumed.  Much has changed in the energy …