ABB REG670 - Page 595

Logic in figure 279 can be summarized as follows:
1. The selected currents and voltage are given to built-in protection elements. Each
protection element and step makes independent decision about status of its
START and TRIP output signals.
2. More detailed internal logic for every protection element is given in the following
four figures.
3. Common START and TRIP signals from all built-in protection elements & steps
(internal OR logic) are available from multipurpose function as well.
AND
Selected v oltage
X
StartCurr_OC1
a
b
a>b
Voltage
control or
restraint
feature
OC1=On
BLKOC1
Directionality
check
Current
Restraint
Feature
I
measured
> k I
restraint
DIR_OK
Inverse
DEF
DEF time
selected
Inverse
time
selected
OR
Enable
second
harmonic
IEC05000831-2-en.vsdx
STOC1
TROC1
AND
BLKTROC1
Selected r estrain current
AND
Second harm onic
check
a
b
a>b
BlkLevel2nd
IEC05000831 V2 EN
Figure 280: Simplified internal logic diagram for built-in first overcurrent step that is, OC1 (step OC2 has the
same internal logic)
1MRK502052-UEN B Section 11
Multipurpose protection
589
Technical manual