SPDC Terms beginning with M

Terms and definitions extracted from current SPDC published documents
Click one of the capital letters above to advance the page to terms beginning with that letter.
main overcurrent protective device

The first overcurrent device between the secondary terminals of the distribution or power class transformer and the load terminals of the service entrance equipment. Also identified as the service entrance main.
[C62.72-2007]

main terminal 1

The main terminal that is named 1 by the device manufacturer.
[62.37-1996]

main terminal 2

The main terminal that is named 2 by the device manufacturer.
[62.37-1996]

main terminals

The two terminals through which the principal current flows.
NOTE: The main terminals may be named by application usage. In telecommunications, terminals may be named after the line connections of R(ing), T(ip), and G(round) or A, B, and C(ommon).
[62.37-1996]

mains

The ac power source available at the point of use in a facility. It consists of the set of electrical conductors (referred to by terms including service entrance, feeder, or branch circuit) for delivering power to connected loads at the utilization voltage level.
[C62.41.1-2002]

mains

The ac power source available at the point of use in a facility. It consists of the set of electrical conductors (referred to by terms including service entrance, feeder, or branch circuit) for delivering power to connected loads at the utilization voltage level.
[C62.72-2007]

maximum continuous operating voltage (MCOV)

The maximum designated root-mean-square (rms) value of power-frequency voltage that may be applied continuously between the terminals of the arrester.
[C62.41.1-2002]

maximum continuous operating voltage (MCOV)

The maximum designated root-mean-square (rms) value of power-frequency voltage that may be applied continuously between the terminals of the arrester.
[C62.11-2005]

maximum continuous operating voltage (MCOV)

The maximum designed root-mean-square (rms) value of power frequency voltage that may be applied continuously between the terminals of the arrester.
[C62.72-2007]

maximum continuous operating voltage rating (MCOV)

The maximum designated root-mean-square (rms) value of power frequency voltage that may be applied continuously between the terminals of the arrester.
[C62.22-2009]

maximum design cantilever load-static (MDCL-static)

The maximum cantilever load the surge arrester is designed to continuously carry.
[C62.11-2005]

maximum discharge current

Ip
The maximum surge current that the SPD withstands without damage. The maximum discharge current is a peak impulse current, with a wave shape of 8/20.
[C62.34-1996]

maximum junction temperature

TJM
The maximum value of permissible junction temperature, due to self heating, which a device can withstand without degradation.
[C62.35-2010]

maximum junction temperature

TJM
The maximum value of permissible junction temperature, due to self heating, which a thyristor SPD can withstand without degradation.
[62.37-1996]

maximum rating (absolute maximum rating)

A rating that establishes either a limiting capability or a limiting condition beyond which damage to the device may occur.
NOTE: A limiting condition may be either a maximum or a minimum.
[62.37-1996]

maximum system voltage

Vm
The highest root-mean-square (rms) phase-to-phase voltage that occurs on the system under normal operating conditions, and the highest rms phase-to-phase voltage for which equipment and other system components are designed for satisfactory continuous operation without deterioration of any kind.
[C62.82.1-2010]

maximum system voltage

The highest voltage at which a system is operated.
NOTE: This is generally considered to be the maximum system voltage as prescribed in ANSI Std C84.1-1995 (Reaff 2001).
[C62.11-2005]

maximum-continuous operating voltage (MCOV)

Uc
The maximum rms value of power-frequency voltage that may be applied continuously between the terminals of the arrester without degradation or deleterious effects.
[C62.34-1996]

means of grounding

The physical devices by which various degrees of grounding are achieved; e.g., inductance grounding, resistance grounding, or resonant grounding.
[C62.92.1-2000]

measured limiting voltage

The maximum magnitude of voltage that is measured across the terminals of the surge protective device (SPD) during the application of a series of impulses of specified wave shape and amplitude.
[C62.41.1-2002]

measured limiting voltage

The maximum magnitude of voltage that is measured across the terminals of the SPD during the application of a series of impulses of specified wave shape and amplitude.
[C62.34-1996]

mechanical unit

Portion of an arrester in which the valve elements within the unit are mechanically restrained from moving in an axial direction.
[C62.11-2005]

metal-oxide surge arrester (MOSA)

A surge arrester utilizing valve elements fabricated from nonlinear resistance metal-oxide materials.
[C62.11-2005]

metal-oxide surge arrester (MOSA)

A surge arrester utilizing valve elements fabricated from nonlinear resistance metal-oxide materials.
[C62.22-2009]

Mode of Protection

An SPD's protective component(s) may be connected wherever protection is required against transient overvoltages. These may include Line to Neutral (L-N), Line to Ground (L-G), Line to Line (L-L) and Neutral to Ground (N-G).
[C62.62-2010]

multiport surge protector

A surge protector that provides surge protective function to two or more circuits, such as, but not limited to, paired conductors, coaxial cables, or mains, whereby all conductors connected to the protected circuits are routed through a common enclosure having a shared common terminal.
[C62.36-2000]