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14.7.2.2.1.1 Parameters
Fig. 59
Type:
Base current (Ieb):
Time multiplier (k):
The trip time is calculated according to British Standard (BS 142) when the time multiplier k is
used. When the time multiplier k is set to one (k=1) the IDMT curve is in accordance with IEC
60255-3.
Parameter
Type
Base Current (Ieb)
Time Multiplier (K)
The threshold setting range is expressed in primary current Ampere [A], up to 2.40 In where In is
the Nominal Primary Current value entered in the General Settings.
14.7.2.2.2 Operation criteria
If the measured RMS current exceeds the setting threshold value (Base current Ieb), by a factor of
1.2 for at least one phase, then the protection function is started.
The protection function will remain in START status until there is at least one phase started. It will
return to passive status and the start signal will be cleared if the current falls below 115% of the
setting threshold value for all the phases. When the protection enters the start status the operating
time is continuously recalculated according to the set parameters and measured current value. If
the calculated operating time is exceeded, the function goes into TRIP status and the trip signal
becomes active.
Tripping characteristic according to the IEC 60255-3 curve
definition.
Current threshold for start condition detection.
Time multiplier to vary time delay for Trip condition.
Values
Default
NI, VI, EI, LTI
NI
0.20 ... 2.40 p.u. di In
2.0 In
0.05 ... 1.50
1
Step
Unit
Explanation
–
–
Tripping curve.
1
A
Current threshold.
0.05
–
Time multiplier
(BS 142).
67
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