Multi-function protection relays calculate and use symmetrical components to enhance their performance during system faults. This can be illustrated in two specific examples: (1) zero-sequence current elimination for transformer differential protection and (2) negative-sequence current detection to inhibit out-of-step blocking. Zigzag Transformer Inside Transformer Differential Zone A shunt-connected zigzag transformer provides a zero-sequence current sink for ungrounded systems such as …
Everyone wears clothes, at least when out in public. However, not everyone needs to wear clothes specially designed and tested to protect them from hazards they could find in their workplace. If your employees work on or near electric power, generation, transmission, and distribution equipment, specialized clothing is necessary for certain tasks. OSHA 29 CFR 1910.269 states that employers must …
This month’s Tech Quiz takes a bit different look at NFPA 70E requirements. What is involved in electrical testing? As with most things, it’s not as simple as it may seem. 1. If you are a crew leader, what is the first thing you would do to test a transformer? a. De-energize it b. Isolate it by lockout/tagout (LOTO) c. …
The National Fire Protection Association (NFPA®) revised its NFPA 70E, Standard for Electrical Safety in the Workplace in 2018 “to assist OSHA in preparing an electrical safety standard that would serve OSHA’s needs and that could be expeditiously promulgated through the provisions of…the Occupational Safety and Health Act.” Responsible electrical test instrumentation manufacturers accept 70E as a valuable guideline as …
Many companies and people rely on NFPA 70E to guide them as they develop and implement electrical safe work practices. They look at a line or possibly a paragraph or two and believe they have the gist of the issue. Maybe, but they often misinterpret what they read or implement it incorrectly. Unfortunately, there’s a plethora of misleading or incorrect …
It was great seeing everyone at Power Test 2019 in Texas! The event went very well, and that’s due to our sponsors, Corporate Alliance Partners, trade show vendors, and most important — the hard work and dedication of the NETA Staff. Mark your calendars for PowerTest 2020 in Chicago February 24 – 28, 2020, and make plans to join us …