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current (I
/I
). This will be affected to a lesser extent than the measurement of negative sequence
2
1
current alone, since the ratio is approximately constant with variations in load current. Hence, a
more sensitive setting may be achieved.
At the moment when the circuit breaker is closed, because the three poles of the circuit breaker
are discrepant for a very short time, and if the broken conductor protection is enabled, it is easy to
make the broken conductor protection pick up, and it will restore after the load current is stable.
The logic diagram is as shown below. The ratio of I
threshold and if the threshold is exceeded then the delay timer is initiated.
Figure 3.8-1 Logic diagram of the broken conductor protection
Where:
[50BC.I2/I1_Set] is the ratio setting of the broken conductor protection;
"t
" is the setting [50BC.t_Op], the time setting of the broken conductor protection;
BCP
[50BC.En] is the logic setting of the broken conductor protection;
[50BC.En1] is the binary signal for enabling the broken conductor protection;
[50BC.Blk] is the binary signal for blocking the broken conductor protection.
3.8.2 Broken Conductor Protection Settings
All the settings of the broken conductor protection are listed in the following table. For the
information about the common explanation of the settings, see Section 7.3.
No.
Menu text
1
50BC.I2/I1_Set
2
50BC.t_Op
3
50BC.En
4
50BC.OutMap
3.9 Breaker Failure Protection
3.9.1 Breaker Failure Protection Theory
The circuit breaker failure protection is specially applied for re-tripping the circuit breaker, when
PCS-9611 Feeder Relay
I
/I
> [50BC.I2/I1_Set]
2
1
[50BC.En]
[50BC.En1]
[50BC.Blk]
The ratio setting for the broken conductor
protection
The time setting for the broken conductor
protection
The logic setting for the broken conductor
protection
The output matrix setting of the broken conductor
protection
Date: 2014-04-08
/I
is calculated and is compared with the
2
1
t
0
&
BCP
Explanation
3 Operation Theory
[50BC.St]
[50BC.Op]
Range
0.10~1.00
0~200s
0~1
0x00000 ~
0xFFFFF
Step
0.001
0.001s
1
1
3-35
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