Siemens 7SR12 Argus - Broken Conductor (46 BC)

7SR11 & 7SR12 Commissioning and Maintenance Guide
©2017 Siemens Protection Devices Limited Chapter 6 Page 66 of 72
3.4 Broken Conductor (46BC)
7SR
12
46
BC
46
NPS
(x
2
)
37
(
x2
)
49
50
BF
51
V
V
L
1
(V
A
)
V
L
2
(
V
B
)
V
L
3
(V
C
)
I
L
1
(
I
A
)
81
HBL
2
37
(x
2)
49
50
BF
51
V
I
L
2
(
I
B
)
81
HBL
2
37
(
x2
)
49
50
BF
51
V
I
L
3
(
I
C
)
81
HBL
2
I
4
(
I
G
)
74
T
/
CCS
NOTE
:
The use of some
functions are mutually exclusive
67
/
50
(
x
4)
67
/
51
(x
4)
67
/
50
N
(x
4
)
67/
50
(x
4)
67
/
50
(x
4
)
67
/
51
(
x
4)
67/
51
(x
4)
67
/
51
N
(x
4)
67
/
50
SEF
67
/
51
SEF
27
59
(
x
4)
27
59
(
x4
)
27
59
(x
4)
79
Optional
Note
:
Example shows
Voltage Config =
Van,
Vbn,
Vcn
60
CTS
60
VTS
50
BF
51
c
51
c
51
c
64
H
47
(
x
2)
59
N
(x
2)
81
(
x4
)
Figure 2-26 Broken Conductor
Voltage Inputs: n/a
Current Inputs: I
L1
(I
A
), I
L2
(I
B
), I
L3
(I
C
)
Disable: 51N, 46IT, 46DT
Map Pickup LED: 46BC - Self Reset
Broken Conductor uses the ratio of NPS current to PPS current to detect an open circuit conductor . These
quantities can be produced directly from many advanced test sets but with limited equipment the following
approach can be applied.
Apply 3P balanced current with normal phase rotation direction. This current will consist of PPS alone, no NPS or
ZPS.
Increase 1 phase current magnitude in isolation to produce NPS. The single phase unbalance current will contain
equal quantities of ZPS, NPS and PPS. The NPS component will be 1/3 of the unbalance current and the total
PPS component will be value of the original balanced 3P current plus 1/3 of the additional unbalance current. i.e.
as the single phase unbalance current increases, the ratio of NPS to PPS will also increase. The levels of each
sequence component current can be monitored in the Current Meters in Instruments Mode.
Inject 1A of balanced current. Gradually increase imbalance current, operating level should be as follows: