IEC05000016-2-en.vsd
Voltage
IDMT Voltage
Time
UL1
UL2
UL3
IEC05000016 V2 EN
Figure 235:
Voltage used for the inverse time characteristic integration
Operation of the trip signal requires that the overvoltage condition continues for at
least the user set time delay. This time delay is set by the parameter
t1
and
t2
for
definite time mode (DT) and by selected voltage level dependent time curves for the
inverse time mode (IDMT). If the START condition, with respect to the measured
voltage ceases during the delay time, and is not fulfilled again within a user defined
reset time (
tReset1
and
tReset2
for the definite time and
tIReset1
and
tIReset2
for the
inverse time) the corresponding START output is reset, after that the defined reset
time has elapsed. Here it should be noted that after leaving the hysteresis area, the
START condition must be fulfilled again and it is not sufficient for the signal to only
return back to the hysteresis area. The hysteresis value for each step is settable
HystAbsn
(where
n
means either 1 or 2 respectively) to allow a high and accurate reset
of the function. For OV2PTOV the IDMT reset time is constant and does not depend
on the voltage fluctuations during the drop-off period. However, there are three ways
to reset the timer: either the timer is reset instantaneously, or the timer value is frozen
during the reset time, or the timer value is linearly decreased during the reset time.
Section 9
1MRK502052-UEN B
Voltage protection
498
Technical manual
Summary of Contents for Relion REG670
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