Glossary of Terms - M

MagneX Interrupter - CPS's primary breaker/switch which takes the place of a weak link and secondary breaker in a CSP (completely self-protected) transformer.

Margin or Protection - The difference between arrester characteristics and equipment withstand level at any given instant of time. This is a factor of safety when considering equipment protection. The margin of protection accounts for various unknowns, such as unusually high magnitudes of lightning current, separations of transformer and equipment, and voltage withstand reduction caused by deterioration of old equipment.

Maximum Continuous Operating Voltage - The maximum designated root-square (rms) value of power frequency voltage that may be applied continuously between the terminals of the arrester.

Maximum Time Current Curve - A curve plotted on log-log paper that describes the time to complete interruption at a particular current for a specific device; a complete set of points (curve) containing the absolute maximum time to circuit interruption at a specific current for a particular device.

MCM - Thousand circular mils-conductor sizing above 4/0.

MCOV - Refer to Maximum Continuous Operating Voltage.

Metal Enclosed - Surrounded by a metal case of housing, usually grounded.

Metal Oxide Surge Arrester - A surge arrester utilizing valve elements fabricated from non-linear resistance metal oxide materials.

Metalclad - Devices in which the conducting parts are entirely enclosed in a metal casing.

Mini-ELSP - CPS's small amperage rated ELSP fuses, i.e., 30, 40, 50 A. The term "mini" comes from the reduction in size compared to the standard ratings.

Minimum Melt Time Current Curve - A curve plotted on log-log paper that describes the time to complete melting for a specific interrupter; a complete set of points (curve) containing the absolute minimum time to melt at a specific current for a particular device.

MOV - Metal Oxide Varistor arrester technology/design.

M.O.V.E. - CPS's Metal Oxide Varistor Elbow (Deadfront) Arrester.

M-Spot - A globule of metal attached to the main element of a fuse used to lower the melting temperature of the main element at that point through an amalgamation process (used in the NX fuse design).

Glossary Index