When performing condition analysis on medium-voltage circuit breakers located in metal-clad switchgear, it is necessary to be aware of all potential hazards. The person performing the condition analysis must be qualified to perform the task and have a solid understanding of each possible hazard they may encounter as well as ways to minimize the risks. To better understand the hazards …
The technician’s job is usually to ensure the lights are on, but we often need to shut a facility down to perform much needed outage-based maintenance. This switching activity is often straightforward, but when the electrical system is complex and several issues exist, unexpected events can occur. Our team was recently fortunate to be awarded a major contract to provide …
Historically, CT connections compensated for the phase shift across a transformer when applying differential protection prior to the advent of numerical transformer protection relays. For example, a delta-wye transformer would have wye connected CTs on the delta side and delta connected CTs on the wye side. The delta connected CTs have the same connection as the transformer delta connected winding …
At 5:45 AM on a particularly cold winter day, an industrial manufacturing plant experienced a significant electrical fault event on a 15kV substation that feeds power to approximately 30% of the manufacturing operations. FAULT ON FEEDER M1A: WHAT HAPPENED? The main circuit breaker in one of the plant’s three medium-voltage substations experienced a fault, arc flash event, and subsequent trip …
In this issue of NETA World, we focus on medium-voltage circuit breaker test methods and the analysis of the resulting test data from those methods. Be sure to check out “Power Factoring Medium-Voltage Breakers” by Rick Youngblood of Electrical Maintenance & Testing and “The Why of Medium-Voltage Circuit Breaker Testing” by Paul Grein of Group CBS Testing for a good …
This edition of the Tech Quiz discusses one thing we all deal with, either at home or at work: low-voltage circuit breakers. Typically, they can last for years without causing problems, but they do require some maintenance and care. Continue on to find out what’s in store for you! 1. When the topic of low-voltage circuit breakers comes up, what …
Falls from ladders account for 20% of all fatalities and lost-workday injuries in general industry according to Occupational Safety and Health Administration (OSHA) statistics. Ensuring that all ladders meet OSHA and American National Standards Institute (ANSI) standards is critical in mitigating this statistic. OSHA Regulatory Requirements OSHA published an update to its walking-working surface rule (Subpart D) for general industry …
Emergencies always seem to occur on Fridays and weekends, and true to form, a panicked customer called about a power outage to a significant portion of a college campus on a Friday morning. It seemed likely to be a 4,160 volt cable or unit substation problem, so we pulled two technicians away from an acceptance testing project and got them on …
Multi-function numerical generator protection relays can calculate the insulation resistance of a synchronous generator field winding to ground. The calculation can be performed on an energized or de-energized generator. The particular relay discussed in this article uses a separate module located close to the rotor slip rings and brushes to monitor the field. The close proximity of the module to …
This issue of NETA World continues with the deep dive into the NFPA 70E revisions that went into the 2021 edition. Part 1 in the Winter 2020 issue covered the reorganization (which was not nearly as extensive as in previous editions); reviewed Article 100 Definitions; and began on Article 110 General Requirements for Electrical Safety-Related Work Practices with Section 110.1 …