IEC 60099-6:2002 pdf download
IEC 60099-6:2002 pdf download.Surge arresters – Part 6: Surge arresters containing both series and parallel gapped structures – Rated 52 kV and less.
2.9
continuous operating voltage of an arrester, U
continuous operating voltage is the designated permissible r.m.s. value of power frequency
voltage that may be applied continuously between the arrester terminals in accordance
with 7.5
2.10
rated frequency of an arrester
frequency of the power system on which the arrester is designed to be used
2.11
disruptive discharge
phenomena associated with the failure of insulation under electric stress, which include a collapse of voltage and the passage of current
NOTE I Th. term applies to electncal breakdowns in solid, liquid and gaseous dielectric, and combinations of [ties.
NOTE 2 A disruptIve discharge In a solid delectnc produces p.rman•nt 1051 of electric strengtti. In a liquid or gaseous dieleclric lb. gsa may be only temporary
2.12
puncture (breakdown)
disruptive discharge through a solid
2.13
flashover
disruptive discharge over a solid surface
2.14
Impulse
unidirectional wave of voltage or current which without appreciable oscillations rises rapidly to a maximum value and falls — usually less rapidly — to zero with small, if any, excursions of opposite polarity
NOTE Th, parameters which define a voltage or current impulse ar. polarity, peak value, front tim. and time to half value o,, the tail.
2.15
designation of an impulse shape
combination of two numbers, the first representing the virtual front time (T1) and the second the virtual time to half value on the tail (‘2)’ written as T11T2, both In is, the sign P having no mathematical meaning
2.16
steep current Impuls.
current Impulse with a virtual front time of 1 js with limits In the adjustment of equipment such that the measured values are from 0.9 us to 1,1 ps and the virtual time to half value on the tail not longer than 20
2.17
lightning current impulse
an 8120 current impulse with limits on the adjustment of equipment such that the measured values are from 7 s to 9 s for the virtual front time and from 18 us to 22 ps for the time to half value on the tail
NOTE The time to half value on the tat is not cflh,cal and may hae any tolerance during the, residual voltage type tsts, see 7.3.1.
2.18
long duration current impulse
rectangular impulse which rises rapidly to maximum value, remains substantially constant for
a specified period and then falls rapidly to zero. The parameters which define a rectangular
impulse are polarity, peak value, virtual duration of the peak and virtual total duration.
2.19
peak (crest) value of an impulse
maximum value of a voltage or current impulse
NOTE Superimposed oscillations may be disregarded, see 7.4.2 c) and 7.5.3.2 e).
2.20
front of an impulse
part of an impulse which occurs prior to the peak
2.21
tail of an impulse
part of an impulse which occurs after the peak
2.22
virtual origin of an impulse
point on a graph of voltage versus time or current versus time determined by the intersection between the time axis at zero voltage or zero current and the straight line drawn through two reference points on the front of the impulse
NOTE 1 For current impulses the reference points are 10 % and 90 % of the peak value.
NOTE 2 This definition applies only when scales of both ordinate and abscissa are linear.
NOTE 3 If oscillations are present on the front, the reference points at 10 % and 90 % should be taken on the
mean curve drawn through the oscillations.
2.23
virtual front time of a current impulse, T1
time in jis equal to 1,25 multiplied by the time in lis for the current to increase from 10 % to
90 % of its peak value
NOTE If oscillations are present on the front, the reference points at 10 % and 90 % should be taken on the mean curve drawn through the oscillations.
2.24
virtual steepness of the front of an impulse
quotient of the peak value and the virtual front time of an impulse
2.25
virtual time to half value on the tail of an impulse, T2
time interval between the virtual origin and the instant when the voltage or current has decreased to half its peak value, expressed in ps
2.26
virtual duration of the peak of a rectangular impulse
time during which the amplitude of the impulse is greater than 90 % of its peak value
2.27
virtual total duration of a rectangular impulse
time during which the amplitude of the impulse is greater than 10 % of its peak value
NOTE If small oscillations are present on the front, a mean curve should be drawn in order to determine the time at which the 10 % value is reached.
