Micom P634 - Limit Value Monitoring (Function Groups LIM_1 to LIM_3); Monitoring Minimum and Maximum Phase Currents

3.33 Limit Value Monitoring (Function Groups LIM_1 to LIM_3)
Each of the limit value monitoring functions, LIM_1, LIM_2 and LIM_3, is designed
for the monitoring of the minimum and maximum phase currents for a user-
selected transformer end.
The limit value monitoring functions can be enabled or disabled using setting
parameters.
3.33.1 Monitoring Minimum and Maximum Phase Currents
Three limit value monitoring functions (LIM_1, LIM_2 and LIM_3) are
implemented. These can each be assigned to one of the transformer ends (a, b,
c, d) or to the virtual transformer end formed by current summation over two
user-selected transformer ends.
For each limit value monitoring function, a setting parameter is provided for this
assignment by the user. The function will then monitor the minimum and
maximum phase currents for the selection. If a maximum phase current exceeds
the relevant set threshold or if a minimum phase current falls below the relevant
set threshold, a signal is issued once a set time has elapsed.
Function group LIM_1 will serve as an example to illustrate the operation of the
limit value monitoring functions in the following figures.
64Z5080A
LIM_1:
Select. meas. input
[ 019 111 ]
0
1
2
4
0: End a
1: End b
2: End c
4: End d
3: Current summation
40
IA,a
IB,a
IC,a
IN,a
IA,b
IB,b
IC,b
IN,b
IA,c
IB,c
IC,c
IN,c
IA,d
IB,d
IC,d
IN,d
ΣIA
ΣIB
ΣIC
ΣIN
IA,y
IB,y
IC,y
IN,y
3
Fig. 3-171: Selection of measured values
P634
3 Operation
3-216 P634/EN M/R-42-A // P634‑311‑653