Alstom MiCOM P546 - 1.36 Broken conductor detection

Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546 (OP) 5-97
OP
INTSIG Current Prot SEF Trip
INTSIG ISEF < Fast Undercurrent
DDB Bfail 1Trip 3ph (623)
&
&
&
&
SET: CB Fail 1 Timer
0
0
1
Alarm Breaker
Fail
DDB Bfail 2Trip 3ph (624)
SET:
CB Fail 1 Status
SET:
CB Fail 2 Status
Enable
Enable
Disbale
Disbale
&
0
1
t
0
&
1
&
1
1
1
&
1
S
R
Q
S
R
Q
S
R
Q
S
R
Q
1
1
1
DDB External Trip A (479)
INTSIG Any Trip Phase A
INTSIG IA< Fast Undercurrent
DDB External Trip B (480)
INTSIG IB< Fast Undercurrent
DDB External Trip C (481)
INTSIG IC< Fast Undercurrent
INTSIG Any Trip Phase B
INTSIG Any Trip Phase C
DDB External Trip A (479)
DDB Pole Dead A Dead (674)
Setting
Ext Tip Reset
0 I< Only
1 CB Open & I<
2 Prot Reset & I<
S
R
Q
DDB External Trip B (480)
DDB Pole Dead B Dead (675)
Setting
Ext Tip Reset
0 I< Only
1 CB Open & I<
2 Prot Reset & I<
S
R
Q
DDB External Trip C (481)
DDB Pole Dead C Dead (476)
Setting
Ext Tip Reset
0 I< Only
1 CB Open & I<
2 Prot Reset & I<
1
S
R
Q
S
R
Q
DDB External Trip3ph (478)
DDB All Poles Dead (672)
Setting
Ext Tip Reset
0 I< Only
1 CB Open & I<
2 Prot Reset & I<
SET: CB Fail 1 Timer
SET: CB Fail 1 Timer
SET: CB Fail 2 Timer - SET CB Fail 1 Timer
t
t
t
P1108ENi
Figure 67 CB2 failure logic for P544 and P546 models
1.36 Broken conductor detection
The relay
incorporates an element which measures the ratio of negative to positive phase
sequence current (2/1). This will be affected to a lesser extent than the measurement of
negative sequence current alone, since the ratio is approximately constant with variations in
load current. Hence, a more sensitive setting may be achieved.
The logic diagram is as shown below. The ratio of 2/1 is calculated and is compared with
the threshold and if the threshold is exceeded then the delay timer is initiated. The CTS
block signal is used to block the operation of the delay timer.
I2/I1 Above
Threshold
P1639ENa
I1
&
I2
CTS Block
Delay Timer
Broken
Conductor Trip
Figure 68 Broken conductor logic