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7SR11 & 7SR12 Commissioning and Maintenance Guide
2.14.2 Undervoltage Guard (27/59UVG)
If any 27 Undervoltage element is set to be inhibited by the 27 Undervoltage Guard element, this function should
be tested.
Connect the test voltage inputs to suit the installation wiring diagram utilising any test socket facilities available. It
may be useful to temporarily map an LED as 'General Pickup' to assist during testing. 27UVG operation will reset
the General Pickup if no other element is operated. This LED should not be set as 'Hand Reset' in the Output
matrix.
Starting from nominal voltage, apply a step decrease to the applied voltage to a level below the 27 Undervoltage
setting but above the 27UVG setting such that an Undervoltage element operation occurs. Slowly reduce the
applied voltage until the 27 Undervoltage element resets, this can be detected by the General Pickup LED reset if
no other element is operated (this includes any Undervoltage element which is not UV Guarded).
Phase
Setting
(Volts)
UVG
2.14.3 NPS Overvoltage (47)
I
L1
I
L2
I
L3
Voltage Inputs:
Current Inputs:
Disable:
Map Pickup LED:
©2017 Siemens Protection Devices Limited
Tolerance
V element
Used for test
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 2-16
V
(V
), V
(V
L1
A
L2
B
n/a apply zero current to stabilize other functions
27/59, 59N, 60VTS
47-n - Self Reset
Blocked
Volts
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)
67/
67/
46
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
NPS Overvoltage
), V
(V
)
L3
C
NOTES
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
Chapter 6 Page 48 of 72
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