This edition of Tech Quiz covers protective relays. Many years ago, as I was teaching a protective relay class, a student asked, “What are these things?” I replied, “Relays,” to which he answered, “No, relays are those little black plastic things that go click-click.” I made sure to call them protective relays from then on. Things in the protective relaying …
Fall protection requirements and equipment varies depending upon where the work is being performed. The regulations can be confusing for some employees, so it is up to the manager or safety professional to understand the work, the environment the work is being performed in, and the equipment needed to mitigate the hazard of falling from height. When Is Protection Required? …
Relay personnel responsible for testing protective relays are often called upon to troubleshoot and gather system data such as settings and event recordings when a major event occurs (for this example, a large generator trip). If only electromechanical relays are installed and no digital fault recorder is available, it can be difficult to determine the root cause of the trip …
In this issue of NETA World, we begin to explain some of the major changes in the 2021 edition of NFPA 70E. So whether you love the 70E, or find it a challenge and don’t want to deal with it…because your life at work is mandated by it, and you know what that means: Do it or else! But that …
This edition of NETA World features articles on electrical power system protection. Protection schemes covering feeder, generation, transmission, and transformers may have many similarities, but they often contain specific functions or schemes unique to that type of equipment. Be sure you check out this edition’s four feature articles: “Challenges in Transformer Protection Testing,” by Scott Cooper of OMICRON electronics “Testing …
First, let’s look at some industry-accepted definitions to establish context. Low voltage is anything below 1 kV. The common building-wiring voltages are 120, 240, 480, and 600 V. To the uninitiated, this can seem confusing and even ridiculous. Get across 600 V, and it can fry you like bacon, but in industry parlance, it is still low voltage. Put into …
Cable testing is one of the oldest forms of testing in the industry. At first, cables were tested using DC voltages, but this was found to damage newer cable types, so additional cable testing methods were developed. This issue’s Tech Quiz takes a look at cable testing. 1. During the early years of cable testing, which two primary types of …
Many regulatory agencies direct which documents are required to perform a company’s tasks. In some cases, federal and state requirements must be adhered to for the same task or hazard. For example, the United States Environmental Protection Agency (US EPA) and state environmental agencies, such as the Massachusetts Department of Environmental Protection (MA DEP), regulate potential environmental impacts that may …
May 2020 was a difficult month for our nation, and 2020 is certainly shaping up to be a difficult year. As essential service providers, many in our industry were called upon to maintain or continue building the nation’s infrastructure. We all understand and appreciate that hospitals, emergency services, government facilities, manufacturing, and even residences could not function without power, and …
This article demonstrates how CT saturation can adversely affect transformer differential protection and how to easily mitigate its effects via inbuilt relay functions. The solution is to provide calculations and simulation for a three-phase fault on the low side of the transformer just external to the CTs. Application The application is for a three-phase delta-wye connected transformer serving station load …