The share of wind power in total electric power generation is expected to increase, and with that comes a requirement for this carbon-free source to be more reliable. The wind turbine, which is the most important component of a wind power system, is exposed to harsh environmental conditions and electrical transients such as lightning strikes. Naturally, understanding the lightning protection …
The growth in renewable energy power generation will continue into the future. What has been lacking is focus on the electrical hazards in construction and fabrication, commissioning, operation, and maintenance. However, requirements in NFPA 70E, Standard for Electrical Safety in the Workplace and CSA Z462, Workplace electrical safety Standard do apply to renewable power generation. ARC FLASH AND SHOCK HAZARDS …
A test technician’s toolbox can never have too many options. The more ways we can detect or confirm a problem in a piece of equipment, the better. Early in my career at Duke Energy, I was never satisfied with just one test result indicating a problem, and I often second-guessed myself as to whether the equipment was bad or if …
Circuit breakers used in low-voltage applications include air circuit breakers, insulated-case and molded-case circuit breakers, and miniature circuit breakers. Air circuit breakers or low-voltage power circuit breakers typically function as the incoming device on a low-voltage switchboard. In the event of an overload condition or short circuit, current sensors in low-voltage power circuit breakers measure high currents and send the …
Low-voltage circuit breakers are predominant in virtually every electrical power system. A 2008 NETA survey and associated IEEE paper showed that 22% of these breakers did not follow their time-current characteristics, and 10.5% did not operate at all when service-aged maintenance was undertaken. The majority of failures were mechanical in nature; this indicates regular maintenance must be a priority. Low-voltage …
Transformer differential protection based on ANSI 87 is one of the most common protection methods for large power transformers due to its outstanding speed and accuracy. However, given the complexity of this method when applied on delta-wye grounded transformers, mistakes made during the design and/or installation phases might not be detected promptly and can eventually cause an undesired operation — …
Relaying current transformers serve as critical components in the design of a protection scheme. CT performance under fault conditions should be within its operating characteristics for a true representation of fault magnitudes and reliable operation of the protection scheme. To ensure proper installation and operation, CTs are often subjected to one or more tests performed in accordance with standards including …
Rapid photovoltaic (PV) penetration into the electric grid has mandated deeper operational and technical understanding of protection schemes in PV farms. An effective protection scheme ensures a grid-connected system functions reliably and securely, and testing and commissioning the entire protection scheme to prove its operational success is of paramount importance. This article presents a standard grid-tie photovoltaic farm architecture and …
Most of us started our electrical careers with fairly good knowledge about the practical aspects of our jobs. We understood voltage, current, power, resistance, etc. We mastered the more esoteric areas such as electrical fields and stress control and only revisited these topics if our day-to-day job required it. Partial discharge (PD) is one of those areas where we might …
As time progresses and a cable system ages, the system’s bulk dielectric strength degrades. During this aging process, artifacts such as water trees, delamination, voids, and shield corrosion raise the local stress placed on the cable during normal operation. The exact way in which the strength of a device degrades depends upon many factors including voltage, thermal stresses, maintenance practices, …