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2.9
Sensitive Earth fault (67/50S,67/51S)
I
L1
I
L2
I
L3
Voltage Inputs:
Current Inputs:
Disable:
Map Pickup LED:
Other protection functions may overlap with these functions during testing, it may be useful to disable some
functions to avoid ambiguity. Derived EF, Sensitive EF & Restricted EF protections can be Enabled/Disabled
individually or as groups in the 'Function Config' menu.
Sensitive EF elements can be separated from Derived EF by secondary injection of current through the I
circuit only.
If any of these elements are defined as directional the correct voltage phase direction will be required to produce
an operation of those elements.
The 67SEF elements will normally operate on the residual current through the I
on only the real (wattmetric) component of this current by setting 67SEF Ires Select to Ires Real. If this option is
selected, the residual current and voltage should be set in anti-phase during testing to so that the applied current
is purely real and can be measured directly.
If 67SEF Wattmetric is set to Enabled, the residual real power must also exceed the 67SEF Wattmetric Power
setting to permit SEF operation
2.9.1
Directional Polarity
See section Directional Earth Fault Polarity Check above for testing details.
If 67SEF Wattmetric is set to Enabled, the residual real power must also exceed the 67SEF Wattmetric Power
setting to permit SEF operation. As the directional boundary is approached, the Wattmetric current, will by
©2017 Siemens Protection Devices Limited
37
(x2)
(I
)
A
37
(x2)
(I
)
B
37
(x2)
(I
)
C
46
BC
I
(I
)
4
G
27
V
(V
)
59
L1
A
(x4)
27
V
(V
)
59
L2
B
(x4)
27
V
(V
)
59
L3
C
(x4)
Figure 2-10
V
(V
), V
(V
L1
A
L2
B
I
(I
)
4
SEF
64H, 50CBF, 79
51SEF-n/50SEF-n - Self Reset
7SR11 & 7SR12 Commissioning and Maintenance Guide
67/
67/
50
49
51V
50
51
BF
(x4)
(x4)
67/
67/
50
49
51V
50
51
BF
(x4)
(x4)
67/
67/
50
49
51V
50
51
BF
(x4)
(x4)
46
67/
67/
60
60
NPS
50N
51N
CTS
VTS
(x2)
(x4)
(x4)
67/
67/
50BF
50
51
SEF
SEF
NOTE: The use of some
functions are mutually exclusive
47
81
59N
(x2)
(x4)
(x2)
Optional
79
Sensitive Earth Fault
), V
(V
) for directional elements
L3
C
7SR12
81
HBL
51c
2
81
HBL
51c
2
81
HBL
51c
2
64H
Note:
Example shows
Voltage Config =
Van, Vbn, Vcn
74
T/
CCS
input but can be set to operate
4
Chapter 6 Page 33 of 72
input
4
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