GE C70, Instruction Manual

Page: 286 / 708

5-162 C70 Capacitor Bank Protection and Control System GE Multilin
5.6 GROUPED ELEMENTS 5 SETTINGS
5
T he phase directional element responds to the forward load current. In the case of a following reverse fault, the ele-
ment needs some time – in the order of 8 ms – to establish a blocking signal. Some protection elements such as
instantaneous overcurrent may respond to reverse faults before the blocking signal is established. Therefore, a
coordination time of at least 10 ms must be added to all the instantaneous protection elements under the supervi-
sion of the phase directional element. If current reversal is of a concern, a longer delay – in the order of 20 ms –
may be needed.
Figure 5–62: PHASE DIRECTIONAL SCHEME LOGIC
NOTE
FLEXLOGIC OPERAND
FLEXLOGIC OPERAND
FLEXLOGIC OPERAND
FLEXLOGIC OPERAND
SETTING
SETTING
SETTING
SETTING
SETTING
SETTING
PHASE DIR 1
FUNCTION:
PHASE DIR 1 SOURCE:
PHASE DIR 1 BLOCK OC
WHEN V MEM EXP:
PHASE DIR 1
BLOCK:
PHASE DIR 1 ECA:
PHASE DIR 1 POL V
THRESHOLD:
PH DIR1 BLK A
PH DIR1 BLK B
PH DIR1 BLK C
PH DIR1 BLK
IA
No
Seq=ABC Seq=ACB
Yes
VBC VCB
827078A7.CDR
Off=0
V MINIMUM
-Use V when V Min
-Use V memory when
V < Min
I 0.05 pu
Enabled=1
AND
AND
OR
MEMORY TIMER
1 cycle
1 sec
Vpol
0
I
1
RUN AND
PHASE B LOGIC SIMILAR TO PHASE A
PHASE C LOGIC SIMILAR TO PHASE A
OR
USE ACTUAL VOLTAGE
USE MEMORIZED VOLTAGE