Micom P631 - 3.23 Inverse-time Overcurrent Protection (Function Groups IDMT1 and IDMT2)

3.23 Inverse-time Overcurrent Protection (Function Groups
IDMT1 and IDMT2)
The P631 features an inverse-time overcurrent protection function (IDMT
protection). The measured variables to be monitored by the respective IDMT
function are selected by a setting parameter.
Phase current values as well as negative-sequence and residual current
measured values are monitored.
The function group IDMT1 will serve as an example to illustrate the operation of
the IDMT protection functions. The same will apply to function group IDMT2.
62Z5027A
IDMT1:
Select. meas. input
[ 019 106 ]
0
1
IA,y
IB,y
IC,y
IN,y
0: End a
1: End b
0 , 1
IA,a
IB,a
IC,a
IN,a
IA,b
IB,b
IC,b
IN,b
Fig. 3-97: Selection of measured variables for IDMT protection
3.23.1 Enabling or Disabling IDMT Protection
IDMT protection can be enabled or disabled via setting parameters. Moreover,
enabling can be carried out separately for each parameter subset.
3 Operation
P631
P631/EN M/R-11-C // P631-310-650 3-131