Trip Time Dmt And Idmt - Siemens SICAM Manual

Device Functions
4.1 Description
NOTE
i
i
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

4.1.5
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
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
Parameter
I>
tI>
I>>
tI>>
I >
N
tI >
N
Table 4-4
Parameter
I>
I>>
Table 4-5
Parameter
tI>
tI>>
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
The following table illustrates the parameter settings and the values.
Table 4-6
Parameter
I>
36
>. Each setting consists of the independent trip-time delays tI>, tI>>, and tI
N
Reference
Attribute
Setting
Delay setting
Setting
Delay setting
Setting
Delay setting
Operate Level
Attribute
Operate level
Operate level
Operate Time
Attribute
Operate time
Operate time
Reference
Attribute
Setting
Value
50 A to 2500 A
40 ms to 60 s
50 A to 2500 A
40 ms to 60 s
0.4 A to 2000 A
40 ms to 60 s
Value
110 % of I> ±5 %
110 % of I>> ±5 %
Value
40 ms ±25 ms
40 ms ±25 ms
, I , and I .
1 2 3
Value
50 A to 2500 A
SICAM, Feeder Condition Monitor, Manual
E50417-H8940-C580-A4, Edition 03.2019
>.
N