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 …
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 …
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 …
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 …
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 …
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 …
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, …
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 …
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 …
There are no one-size-fits-all solutions to the ground fault-protected main circuit breaker issue. Diligent attention to the requirements in the NEC — NFPA 70 and the equipment in the existing installation is required. The 2020 National Electrical Code (NEC – NFPA 70) in Section 230.95 Ground-Fault Protection of Equipment requires ground-fault protection of equipment for solidly grounded wye services of …