SPDC Terms beginning with N

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.
n-gate thyristor

A three-terminal thyristor in which the gate terminal is connected to the n-region adjacent to the region to which the anode is connected and that is normally switched to the on state by applying a negative signal between the gate and anode terminals.
[62.37-1996]

negative differential-resistance (region)

The region of the principal voltage-current characteristic in the switching quadrant where the differential resistance is negative and the thyristor is switching between the breakdown and on-state regions.
[62.37-1996]

negative-breakdown resistance thyristor surge protection device (SPD)

A thyristor SPD, whose static breakdown characteristic has a net negative-resistance slope prior to switching.
[62.37-1996]

nominal discharge current

In
The discharge current that can be applied to an SPD a specified number of times without causing damage to it. The nominal discharge current is a peak surge current, with a wave shape of 8/20.
[C62.34-1996]

nominal rate of rise (of an impulse wave front)

The slope of the line that determines the virtual zero. It is usually expressed in volts or amperes per microsecond.
[C62.11-2005]

nominal rate of rise(of an impulse)

For a wave front, the slope of the line that determines the virtual zero. It is usually expressed in volts or amperes per microsecond.

nominal system voltage

A nominal value assigned to designate a system of a given voltage class.
[C62.41.1-2002]

nominal system voltage

The rms phase-to-phase voltage by which the system is designated and to which certain operating characteristics of the system are related.
NOTE — The nominal system voltage is near the voltage level at which the system normally operates. To allow for operating contingencies, systems generally operate at voltage levels about 5%-10% below the maximum system voltage for which systems components are designed.
[C62.82.1-2010]

nominal system voltage

A nominal value assigned to designate a system of a given voltage class.
NOTE: See ANSI C84.1-1995.
[C62.34-1996]

nominal system voltage

A nominal value assigned to designate a system of a given voltage class.
NOTE: See ANSI Std C84.1-1995 (Reaff 2001).
[C62.11-2005]

nominal system voltage

A nominal value assigned to designate a system of a given voltage class.
[C62.22-2009]

nominal Varistor voltage

VN(dc)
Voltage across the varistor measured at a specified pulsed dc current, IN(dc), of specific duration. IN(dc) is specified by the varistor manufacturer.
[C62.33-1982]

non-repetitive current rating

A maximum rating that may be applied to the device for a minimum of 100 times over the life of the device without failure. During the rated condition, the device is permitted to exceed its maximum rated junction temperature for short periods of time. The device is not required to block voltage or retain any gate control during or immediately following this rated condition until the device returned to the original thermal equilibrium conditions. This rated condition may be repeated after the device has returned to the original thermal equilibrium conditions.
[62.37-1996]

non-repetitive peak forward current

IFSM
Rated maximum (peak) value of ac power frequency forward surge current of specified wave shape and frequency which may be applied for a specified time or number of ac cycles.
[62.37-1996]

non-repetitive peak on-state current

ITSM
Rated maximum (peak) value of ac power frequency on-state surge current of specified wave shape and frequency which may be applied for a specified time or number of ac cycles.
[62.37-1996]

non-repetitive peak pulse current

IPPS
Rated maximum value of peak impulse pulse current of specified amplitude and wave shape that may be applied.
[62.37-1996]

non-self-restoring insulation

An insulation that loses its insulating properties or does not recover them completely, after a disruptive discharge caused by the application of a test voltage; insulation of this kind is generally, but not necessarily, internal insulation.
[C62.82.1-2010]

nonlinear exponent

A measure of varistor nonlinearity between two given operating currents, I1 and I2, as described by I = kVα where k is a device constant, I1 < I < I2, and α
α12, =  log (I2 /I1) / (log(V2 /V1)
[C62.33-1982]

nonlinear load

An electrical load that draws current discontinuously or whose impedance varies during the cycle of the input ac voltage waveform.
[C62.48-2005]

nonlinear load current

Load current that is discontinuous or is not proportional to the ac voltage.
[C62.48-2005]

nonself-restoring insulation

An insulation that loses its insulating properties or does not recover them completely after a disruptive discharge caused by the application of a test voltage; insulation of this kind is generally, but not necessarily, internal insulation.
[C62.22-2009]

normal interruption (rotating electric machinery)

A machine circuit interruption by an interrupting device at a current zero of the fundamental frequency current.
[C62.21-2003]

normal lightning current

Lightning currents of 65 kA or less. See also: severe lightning current.
[C62.11-2005]

normal-mode

The voltage that appears differentially between two signal wires and that acts on the circuit in the same manner as the desired signal.
[C62.72-2007]