This article demonstrates how to use numerical generator protection relay profile capability to measure the stator ground capacitance of a large combustion turbine generator. The measurements are taken when the generator is on-line and running at full speed while the generator breaker is open (no load), and again during startup as the exported power increases. The stator capacitance-to-ground (Figure 1) …
In late August 2022, the NFPA 70E Technical Committee met for the Second Draft meeting related to the revision of what will be the 2024 edition of NFPA 70E, Standard for Electrical Safety in the Workplace. This was the step in the revision process where the 70E Technical Committee meets to review Public Comments as well as NFPA Correlating Committee …
As so many parts of the world face challenges due to extreme weather and geological events, I want to take a moment to recognize electrical workers and their families. As we all have learned, the electrical infrastructure is quite possibly the most essential part of our life these days. We tend to forget that we can’t accomplish many of the …
Thirty-one years into his career, Potomac Testing Project Manager Wyatt Hamrick says he is humbled by the lessons he has learned, but also proud of the many achievements and fond memories his career has provided. With 10 years of service in the U.S. Army and 21 years of electrical testing experience under his belt, Hamrick says his own deep curiosity …
Imagine this: A new hyper-scale data center is built in rural New Jersey. It has more than 100 25 KV cables. Six months into operation, a cable termination fails catastrophically, and the forensic investigation determines that termination workmanship was lacking. Partial discharge caused tracking, and the cable flashed over. But that’s not the nightmare scenario. The nightmare scenario is that the …
Hydro-Quebec (HQ) is a major Canadian utility that manages the generation, transmission, and distribution of electricity to more than 3.8 million customers. Its distribution network includes over 12,000 km (7,456 miles) of medium-voltage underground distribution cables and more than 600,000 accessories — each with potential for failure. Medium-voltage (MV) underground cable systems are a critical part of the distribution network …
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 will depend upon many factors including voltage, thermal stresses, maintenance …
Partial discharge (PD) testing is a form of diagnostic testing for power cable systems. PD testing of medium- and high-voltage cable applications is beneficial when paired with other cable tests including very-low frequency (VLF) and tan delta (TD) tests. Partial discharge testing is another way to judge a cable’s insulation vitality or ability to endure electrical stress. Utilizing PD as …
ANSI/NETA MTS–2019 REVISION IN PROCESS A standards revision is in process for ANSI/NETA–2019, Standard for Maintenance Testing Specifications for Electrical Power Equipment and Systems to be released in March 2023. The initial ballot and public comment period ended on August 29, 2022. The Standards Review Council will review all comments for consideration by the end of October. A second ballot …
The NFPA 70B Committee met via online video calls to review the public inputs on the Second Draft. This meeting was held between April 25–29 2022. Several task groups held side meetings — some late at night and others very early in the morning — to complete the proposed responses to each input. Balloting for the Second Draft 70B closed …