1. Describe the function of polarity marks on current transformers. 2. Transformer differential relays protecting a 50 MVA, 138 kV – 13.09 Y/7.56 kV transformer have been operating normally during the construction phase of a project. When the transformer is being brought up to full load it trips. There is no indication of a fault, as all tests on the transformer and cable …
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 …
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 …
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 …
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 …
Everyone says they want to be safe, but when you get right down to it, some are more serious — or possibly they understand the consequences of incorrect decisions more accurately — than others. Whoever performed the repair in this photo did not have a clue what they were doing or the possible consequences of such shoddy work. Thankfully, we …
This issue of NETA World covers troubleshooting. A big part of that is being able to interpret a schematic, and some of the most difficult are those for circuit breakers (unless you work in the circuit breaker shop, I suppose). Give these questions a try. Here’s a big call-out to retired Instructor Craig Nelson, who got tired of my hand …
This edition of the NETA World is on communications — a very broad, but necessary subject. This Tech Quiz looks at three types of communication: digital substations, three-way communication, and hand signals for heavy lifting and cranes. Every NETA technician should have knowledge of these. 1. Digital substations are based on which IEC standard? IEC 61800 IEC 47855 IEC 60947 …
Wikipedia defines emerging technologies: “Emerging technologies are technologies that are perceived as capable of changing the status quo. These technologies are generally new but include older technologies that are still controversial and relatively undeveloped in potential.” In this issue, we look at some emerging technologies that are in use now or might be in the future. This Tech Quiz is …
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. …