Ground testing is often thought of as ground electrode testing: the measurement of the resistance associated with a particular rod or grounding system. A useful corollary to this is soil resistivity testing. Resistivity is the electrical property of soil itself that determines how well it can carry current. It varies enormously (Table 1) depending on physical and chemical composition, moisture, …
The Tech Quiz questions for this issue concern medium-voltage power system components. FREE QUESTION! What is medium-voltage? Great question, as there are varying answers from NETA, NEMA, NFPA, and IEEE. NETA’s Standards Review Council has defined and classified medium-voltage within the NETA standards as “a class of nominal system voltages greater than 1,000 volts and less than 100,000 volts,” which …
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 …