Glossary of Electric Utility Industry Terms
Mandrel – A cylindrical or cone-shaped device that is pulled through conduit (pipe) to remove debris.
MCM – An obsolete method of measuring conductor size that stands for thousand circular mils. M represents 1,000 (in roman numerals). C represents circular, and mil, M, is 1/1000 of an inch. A wire that is one mil in diameter has an area of one circular mil or 1 MCM. KCMil (see above) has replaced MCM for sizing conductors. (EUSO, IESO)
Microturbine – A tiny jet engine that uses the hot exhaust gas to spin an electric generator.
Mid-Span Tap - A connection from a secondary distribution line to customers that is made in between the poles. The connection in the middle of the span. (CAEDS, EDS)
Midwest Reliability Organization- MRO - See NERC. (EUSO, System operator classes)
MOAB – An acronym for a Motor-Operated Air-Break switch. The “Motor” is an electric motor that allows the switch to be remotely controlled by a system control center. The “Air Break” refers to a visible break in the air that allows crews to see that the switch is truly open.
MRO – Midwest Reliability Organization - See NERC. (EUSO, System operator classes)
MVAR – A unit of measure for reactive power representing megavolt amperes reactive. It is pronounced “mega-var.” (See reactive power)