Siemens 7SR224 - Broken Conductor (46 BC)

7SR224 Argus Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 60 of 73
3.5 Broken Conductor (46BC)
7SR224
46
BC
46
NPS
(x2)
37
(x2)
49
50
BF
51V
V
L1
(V
A
)
V
L2
(V
B
)
V
L3
(V
C
)
V
4
(V
X
)
I
L1
(I
A
)
81
HBL
2
37
(x2)
49
50
BF
51V
I
L2
(I
B
)
81
HBL
2
37
(x2)
49
50
BF
51V
I
L3
(I
C
)
81
HBL
2
60
CTS
60
VTS
I
4
(I
G
/I
SEF
)
74
TCS
(x3)
NOTE: The use of some
functions are mutually exclusive
67/
50
(x4)
67/
51
(x4)
67/
50
(x4)
67/
50
(x4)
67/
51
(x4)
67/
51
(x4)
64
H
27
59
27
59
(x4)
27
59
(x4)
27
59
(x4)
47
(x2)
79
59N
(x2)
Note:
Example shows
Voltage Config =
Van, Vbn, Vcn
81
(x4)
67/
50G
(x4)
67/
51G
(x4)
67/
50S
(x4)
67/
51S
(x4)
27S
59S
27S
59S
27S
59S
Batt
Test
Cap.
Test
Figure 3-5 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.
Note that if the relay is applied on a non-standard A-C-B networks, the positive and negative sequences are
reversed and the 3 phase test supply must be arranged to suit.