Dynamic Testing of Numerical Protection Relays

Steve Turner Columns, Relay Column, Spring 2019 Columns

A numerical protection relay provides multiple functions and typically uses algorithms that do not work on the same principles as older electromechanical relays. Numerical relays are often still tested using old techniques developed long ago for electromechanical relays. One such common technique is referred to as a “static test.” Fault voltage and/or fault current are injected to see whether the …

Sulfur Hexafluoride Gas Hazards

Paul Chamberlain Columns, Safety Corner, Spring 2019 Columns

Sulfur hexafluoride, also known as SF6 gas, is a commonly used and excellent insulator found in many medium to large circuit breakers protecting transmission and distribution equipment. It has been argued that gas-filled breakers are superior to those filled with oil, air, or a vacuum. They operate cooler and with no noise or gas emissions and are considered relatively low …

Sulphur Hexafluoride Circuit Breakers

James R. White Columns, Spring 2019 Columns, Tech Quiz

Sulphur hexafluoride circuit breakers used to be the domain of utilities, but they are liable to be used now by any large- or medium-size industrial. This Tech Quiz will review some of the NETA standard requirements for these circuit breakers. 1. In ANSI/NETA ATS, which ANSI/IEEE standard is referred to if manufacturer’s data is not available? a. C57.04 b. C57.11 …

Computer-Based Technology for Ground Testing

Jeffrey R. Jowett Columns, Spring 2019 Columns, Tech Tips

Since its inception in the early 20th century, testing grounded electrodes has been grounded on one technique and technology only: Fall of Potential. The test instrument made contact with the earth through long leads and driven probes, injected a current between the electrode being tested and a remote probe, and measured the voltage drop caused by earth resistance to another …

Testing Battery Banks

Ron Widup and James (Jim) R. White Columns, NFPA 70E and NETA, Spring 2019 Columns

The 2021 NFPA 70E cycle started last year, and the Second Draft Meeting will convene July 14–19, 2019. One interesting benefit of being on the committee is the information that is shared with us. Some of it is obviously presented to serve one purpose or another, but some of it is put forward by well-known, independent laboratories that have no …