David T. Rollay

Arc resistant equipment for low voltage motor control center applications

Due to recent focus on arc flash hazards, arc resistant equipment is becoming increasingly common in industrial facilities throughout North America. This paper addresses arc resistant equipment as it applies to low voltage motor control centers (NEMA 600V LVMCC/IEC 690V LV controlgear). A brief overview and history of applicable internal arc fault testing guides (IEEE C37.20.7 and IEC/TR 61641) are included. Test procedures and their considerations are reviewed, as well as arc resistant assessment criteria. An examination of the various methods to achieve an arc resistant rating (device limited rating and duration rating) are addressed as well as considerations for implementing arc resistant equipment in pulp, paper, and forest product applications.

CT Saturation Calculations - Are they Applicable in the Modern World? - Part II, Proposed Responsibilities

Part I expressed concerns about using IEEE Standard C37.110-1996 (1+X/R) criteria for sizing current transformers (CTs) for feeder short-circuit conditions [1]. Part II introduces an overview of relay filter algorithms, and proposes responsibilities of the IEEE Power System Relay Committee (PSRC), operating company and engineering company electrical power engineers, CT manufacturers, switchgear manufacturers, and relay manufacturers to guarantee CT/relay system performance. International Electrotechnical Commission (IEC) responsibilities are also included.

Arc-Resistant Equipment

Because of the recent focus on arc flash hazards, arc-resistant equipment is becoming increasingly common in industrial facilities throughout North America. This article addresses arc-resistant equipment as it applies to low-voltage motor control centers (LVMCCs) [National Electric Manufacturing Association (NEMA) 600 V LVMCC/International Electrotechnical Commission (IEC) 690 V LV control gear}. A brief overview and history of applicable internal arc fault testing guides (IEEE C37.20.7 and IEC/TR 61641) are included. Test procedures and their considerations as well as arc-resistant assessment criteria are reviewed. An examination of various methods to achieve an arc resistant rating (device-limited rating and duration rating) as well as considerations for implementing arc-resistant equipment are addressed.