SPDC Terms beginning with I

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.
immunity (to a disturbance)

The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.
[C62.41.1-2002]

impedance grounded neutral system

A system whose neutral point(s) are grounded through an impedance (to limit ground-fault currents).
[C62.82.1-2010]

impulse

A surge of unidirectional polarity.
[C62.22-2009]

impulse

A surge of unidirectional polarity.
[C62.11-2005]

impulse

A surge of unidirectional polarity.
[62.37-1996]

impulse protective level

For a defined wave shape, the higher of the maximum sparkover value or the corresponding discharge-voltage value.
[C62.11-2005]

impulse protective volt-time characteristic

The discharge-voltage time response of the device to impulses of a designated wave shape and polarity, but of varying magnitudes.
[C62.11-2005]

impulse reset time

t(Reset)
The time taken for a device to switch back into the off-state, in the presence of a specified value of dc short-circuit current, after being switched into the on state by a specified impulse.
[62.37-1996]

impulse sparkover volt-time characteristic

The gap sparkover response of the device to impulses of a designated wave shape and polarity, but of varying magnitudes.
NOTE: For an arrester, this characteristic is shown by a graph of crest voltage values plotted against time to sparkover.
[C62.11-2005]

impulse sparkover voltage

The highest value of voltage attained by an impulse of a designated waveshape and polarity applied across the terminals of a gas tube prior to the flow of discharge current. Syn:surge or impulse breakdown voltage.
[C62.31-2006]

impulse sparkover voltage-time curve

A curve that relates the impulse sparkover voltage to the time to sparkover.
[C62.31-2006]

impulse wave

A unidirectional wave of current or voltage of very short duration containing no appreciable oscillatory components.
NOTE: In the case of the 8/20 wave an opposite polarity wave tail underswing of up to 30% is allowed.
[62.37-1996]

impulse withstand voltage

The crest value of an impulse that, under specified conditions, can be applied without causing a disruptive discharge.
[C62.11-2005]

In-Line SPD

A two-port device connected in series between the power supply and a load where the load current passes through the conductive terminals of the SPD such that the removal of the SPD opens the circuit.
[C62.62-2010]

indoor arrester

An arrester that, because of its construction, must be protected from the weather.
[C62.11-2005]

insertion loss

Loss resulting from the insertion of a device into a transmission system, expressed as the ratio of the power delivered to that part of the system following the device, before insertion of the device, to the power delivered to that same part after insertion of the device.
NOTE —The insertion loss is generally expressed in decibels.
[C62.35-2010]

insulation configuration

The complete geometric configuration of the insulation, including all elements (insulating and conducting) that influence its dielectric behavior.
Examples of insulation configurations are phase-to-ground, phase-to-phase, and longitudinal.
[C62.82.1-2010]

insulation coordination

The selection of insulation strength consistent with expected overvoltages to obtain an acceptable risk of failure.
[C62.82.1-2010]

insulation level

A combination of voltage values (both power frequency and impulse) that characterize the insulation of an equipment with regard to its capability of withstanding dielectric stresses.
[C62.22-2009]

insulation resistance

The equivalent insulation resistance of the device, computed by VD / ID
[62.37-1996]

internal insulation

Internal insulation comprises the internal solid, liquid, or gaseous elements of the insulation of equipment, which are protected from the effects of atmospheric and other external conditions such as contamination, humidity, and vermin.
[C62.82.1-2010]

ionization current

The electric current resulting from the movement of electric charges in an ionized medium, under the influence of an applied electric field.
[C62.11-2005]

ionization voltage

A high-frequency voltage appearing at the terminals of an arrester, generated by all sources, but particularly by ionization current within the arrester, when a power-frequency voltage is applied across the terminals.
[C62.11-2005]