NOTE
If any of the timers T1, T2, and T3 is set to 0, the other 2 timers are disabled. For example, if T1=0, T2 and
T3 are disabled.
Trip Time DMT and IDMT
SICAM FCM supports both the DMT and IDMT function.
Definite Minimum Time (DMT)
DMT is applicable for both the phase fault and the ground fault.
The 3 DMT settings are I>, I>>, I
N
>. Each setting consists of the independent trip-time delays tI>, tI>>, and tI
N
>.
The user-defined DMT setting is used to configure various current thresholds for the entire dynamic primary
current range.
If the current in the system exceeds the set threshold and persists for the set time specified, the device indi-
cates a fault. The device provides an option to set for 2 current thresholds and 2 time delay thresholds.
The following table illustrates the parameter settings and the values.
Table 4-3 Reference
Parameter Attribute Value
I> Setting 50 A to 2500 A
tI> Delay setting 40 ms to 60 s
I>> Setting 50 A to 2500 A
tI>> Delay setting 40 ms to 60 s
I
N
> Setting 0.4 A to 2000 A
tI
N
> Delay setting 40 ms to 60 s
Table 4-4 Operate Level
Parameter Attribute Value
I> Operate level 110 % of I> ±5 %
I>> Operate level 110 % of I>> ±5 %
Table 4-5 Operate Time
Parameter Attribute Value
tI> Operate time 40 ms ±25 ms
tI>> Operate time 40 ms ±25 ms
Inverse Definite Minimum Time (IDMT)
IDMT characteristics are defined as Inverse because the trip time is inversely proportional to the fault current
being measured.
In SICAM FCM, the IDMT function supports the Normal Inverse (NI) characteristics. The ANSI codes supported
by the IDMT function are non-directional (51) and directional (67) for overcurrent indication.
IDMT function is applicable only for the phase currents I
1
, I
2
, and I
3
.
The following table illustrates the parameter settings and the values.
Table 4-6
Reference
Parameter Attribute Value
I> Setting 50 A to 2500 A
4.1.5
Device Functions
4.1 Description
36 SICAM, Feeder Condition Monitor, Manual
E50417-H8940-C580-A4, Edition 03.2019
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