Appendix 3 Event Detection Methods
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Appendix
Appendix 3 Event Detection Methods
Transient overvoltage
Measurement method:
• Detected when the waveform obtained by eliminating the fundamental component (50/60/400 Hz) from a waveform
sampled at 2 MHz exceeds a threshold specified as an absolute value.
• Detection occurs once for each fundamental voltage waveform, and voltages of up to 6,000 V can be measured.
Recorded data:
Transient voltage value : Peak value of waveform during 4 ms period after elimination of fundamental component
Transient width : Period during which threshold is exceeded (2 ms max.)
Max. transient voltage value: : Max. peak value of waveform obtained by eliminating the fundamental component during
the period from transient IN to transient OUT (leaving channel information)
Transient period : Period from transient IN to transient OUT
Transient count during period : Number of transients occurring during period from transient IN to transient OUT (tran-
sients occurring across all channels or simultaneously on multiple channels count as 1)
Transient waveforms : Event waveform and transient waveform
(Waveforms are saved for 2 ms before and after the position at which the transient over-
voltage waveform was detected for the first transient IN and 2 ms before and after the
point at which the transient maximum voltage waveform was detected between the IN
and OUT points.)
Event IN and OUT
Event IN : The event occurrence time when the first transient overvoltage is detected during an aggregation period of
approx. 200 ms. indicates the peak voltage value and transient width detected when the threshold was ex-
ceeded.
Event OUT : Indicates the first transient period (difference between the IN time and OUT time) for the approx. 200 ms
aggregation period during which no transient overvoltage was detected for any channel within the first ap-
prox. 200 ms aggregation period following the transient event IN state.
Threshold
Threshold
Transient voltage
Transient width
Event IN
2 ms 2 ms
Sampled
waveform
2 MHz
Elimination of fun-
damental compo-
nent (5 kHz) and
lower
Transient wave-
form after elimina-
tion of fundamental
component
Approx. 200 ms
aggregation
Event IN Event OUT
Event period
Transient waveform (including
fundament component)
The first detected transient wave-
form after event IN is saved.
Transient waveform (including
fundament component)
The waveform with the largest transient
voltage value from the IN to the OUT
point is saved at event OUT.
Event IN
2 ms 2 ms 2 ms 2 ms
Threshold
Approx. 200 ms
aggregation
Approx. 200 ms
aggregation
Approx. 200 ms
aggregation
Threshold
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