Technical Documentation
KSR-Z – Capacitor-Bank Protection Relay
Rev. 04
Page
35
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36
Section 9: Appendix
Appendix A
Explanations of the Current damping function for Ith. Ith is a exponentially damped current value to
simulate thermal measurement. The formula and the drawings below shall help to understand the
Ith function. The drawing below shows cold curve.
Formula:
t = -
ln(1-y)
t = time elapsing until Ie is arrived after applying current at current channel
=
adjusted thermic tau (see referring setting)
y
= Ie / I
Ie = adjusted threshold
I = applied current
t [s]
40
30
20
Ith
Multiple of alarmthreshold
The drawings stated above shows the relation between the ratio of exceeding the adjusted
threshold and the time before Ith has the same value as applied at the current channel. Also the
function of the adjustable value for thermic tau (
can be seen.
