ABB Relion 670 Series Technical Reference Manual page 587

1MRK505222-UUS C
Selected current
PickupCurr_OC1
Voltage
control or
restraint
feature
Selected voltage
Selected restrain current
ANSI05000831 V1 EN
Figure 295: Simplified internal logic diagram for built-in first overcurrent step that is, OC1 (step OC2 has the
same internal logic)
Technical reference manual
ANSI05000170 V1 EN
Figure 294: CVGAPC function main logic diagram for built-in protection elements
Logic in figure 294 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
PICKUP and TRIP output signals.
2. More detailed internal logic for every protection element is given in the following
four figures
3. Common PICKUP and TRIP signals from all built-in protection elements & steps
(internal OR logic) are available from multipurpose function as well.
Enable
second
Second
harmonic
harmonic check
a
a>b
b
OC1=On
BLKOC1
X
DIR_OK
Directionality
check
Current
Restraint
Feature
I > k I
measured restraint
NOT
DEF time
0-DEF
selected
AND
Inverse
Inverse
time
selected
Multipurpose protection
BLKTROC1
0
OR
en05000831_ansi.vsd
Section 10
TROC1
AND
PU_OC1
581