Modern numerical transformer protection relays have powerful logic to prevent unwanted tripping on phase differential during CT saturation for external faults. This article analyzes this logic for a typical application. To demonstrate these protection features, we will simulate the low-side fault current for an out-of-zone fault using the IEEE PSRC CT Saturation Calculator. Note that this type of exercise is …
No good electrical testing field story starts with “everything went perfectly.” Inevitably, things do not go according to plan. Breakers of all types, makes, and models are the source of great stories and hard lessons learned under pressure to get a circuit back in service. The purpose of this article is to share common issues that fall into a few …
This will be the third time since 2011 that we have discussed inadvertent contact with overhead electrical lines. Once in 2011, again in 2017, and now once again in 2025. Why do we talk about the same subject three times every five years or so? Simply put, we aren’t making enough progress (in my opinion) on this particular electrical hazard. …
As we turn the page into summer, this issue of NETA World brings together timely insights and timeless principles that define our profession. It’s an edition that challenges us to think critically about how we work — and why we do what we do. I’m proud to highlight four powerful articles that speak to the core of our mission. “Electrical Infrastructure …
Out of sight, out of mind is a common aphorism, but when it’s applied to standby backup batteries, it can — and does — become catastrophic. Standby battery banks support production lines, hospitals, computer rooms, and entire facilities to provide an alternate power source should utility power fail. The standby battery is the interface between a smooth transition and total …
Partial discharge in electrical equipment insulation can lead to catastrophic failure. NETA Certified Technicians must understand the reasons partial discharge may occur and how to properly detect, diagnose, and correct it. 1. What is partial discharge within an insulating system?a. A brief short circuitb. A voltage spikec. A small explosiond. A small electrical discharge 2. How frequently might partial discharge …
For great leaders, safety is typically not their number one priority; it is an unwavering core value. Priorities change, while values remain constant in all situations. Great leaders also typically want to have success….operational success, individual success, and especially safety success. SAFETY SUCCESS How do you define safety success? Have you achieved safety success if you have zero recordable …
A restricted earth fault (REF) protection element provides sensitive detection of ground faults near the neutral of a transformer wye-connected winding. The sensitivity gains from the REF element are especially more valuable if the equipment is low-impedance grounded. Security of the REF element may be jeopardized by external faults, such as a phase-to-phase-to-ground or an evolving fault with CT saturation. …
Electrical insulation is designed to keep current from flowing where it shouldn’t. Insulation integrity is therefore critical and is assessed via a battery of tests. Many things can compromise the results of these tests, including temperature, humidity, erroneous test procedures, etc. Previously, I wrote about the effects of humidity on insulation integrity tests. This time I focus on erroneous test …
You have probably seen OSHA’s recent guide titled Protecting Employees for Electric-Arc Flash Hazards. If not, you can find it here: https://www.osha.gov/electrical/flash-hazards. OSHA produced the guide to assist employers and employees in understanding and protecting against arc flash hazards, which brings about an interesting thought about OSHA and its relationship to NFPA 70E. It reminds us of how important it …