1. Describe the function of polarity marks on current transformers. 2. Transformer differential relays protecting a 50 MVA, 138 kV – 13.09 Y/7.56 kV transformer have been operating normally during the construction phase of a project. When the transformer is being brought up to full load it trips. There is no indication of a fault, as all tests on the transformer and cable …
People are easily distracted in a world filled with more distractions every day. In this day of modern technology, it is easy to get overwhelmed with the number of distracting devices out there, and these devices have encroached upon the driving environment. Cell phones are convenient means to communicate over long distances, but couple them with texting, email, internet, and …
“What are you doing here?” asked the manufacturer’s testing representative. “We are doing start-up of the gear, and your work seems redundant.” Redundant? That depends on what each of us is responsible for checking. That depends on who is going to ensure that all the known potential failures get checked and as needed, corrected. As an industrial or commercial buyer, …
Numerical protection relays offer the ability to alarm for many abnormal operating conditions, including the health of the relay. Below is a list of typical conditions to alarm for due to an abnormal condition: Overexcitation Phase undervoltage Loss of potential or blown fuse(s) Relay firmware or hardware failure Relay access Over or under station battery DC voltage Trip coil monitoring …
The National Fire Protection Association (NFPA) is best known for the 70 standard, which is a consensus standard reviewed and updated every three years. The NFPA produces many additional standards covering topics such as Aircraft Rescue and Fire Fighting, Finishing Processes, and Wastewater Treatment Plants. There are three standards that pertain directly to electrical workers and equipment: • NFPA 70 …
There is a common, and often used, phrase around Tony Demaria Electric (TDE): “Call Neno.” TDE’s Tony Demaria, Jr. says he doesn’t want to imagine the business without Nenad “Neno” Pasic. “He solves everyone’s problems. It is well known, any time there is a problem, we say ‘Call Neno!’” Demaria says. “Neno is always willing to do whatever it takes …
David Koehler credits his success to his many mentors, excellent managers and colleagues in the industry, and one very important lesson: “Always conduct yourself in a professional and ethical manner,” he says. While that may be important, it’s just one small part of the reason Koehler was presented with this year’s Alliance Recognition Award, which was a complete surprise. “I …
PowerTest 2021, NETA’s premier electrical maintenance and safety conference, ran live from March 8 through 11, 2021. Held virtually, PowerTest TV offered a live keynote, interactive sessions and panels, and a virtual trade show. “Our first virtual PowerTest conference was a huge success,” says Conference Committee Chair Ron Widup of Shermco Industries. “Despite the challenges of COVID-19, PowerTest TV delivered …
Artificial intelligence (AI) systems provide promise in analyzing and evaluating power system data. There is currently a large push to use AI and machine learning (ML) to help reduce time performing maintenance on transformers and predict where and when the next transformer will fail.1,2,3 Major companies in various industries are promoting and telling the wonders of AI and ML: managing …
Every current interruption involves an arc burning between the contacts of a circuit breaker (CB). The produced arc energy and associated pressure increase is used in gas circuit breakers to cool the arc region leading to current interruption. The same arc energy causes wear that can be separated into two main phenomena: • Nozzle ablation, which affects pressure build up, …