Siemens Argus 7SR21 - Page 556

7SR210 & 7SR220 Commissioning & Maintenance Guide
Page 44 of 82 © 2013 Siemens Protection Devices Limited
2.8 Undercurrent. (37)
7SR22
46
BC
46
NPS
(x2)
37
(x2)
49
50
BF
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
I
L2
(I
B
)
81
HBL
2
37
(x2)
49
50
BF
I
L3
(I
C
)
81
HBL
2
60
CTS
I
4
(I
G
)
I
5
(I
SEF
)
74
TCS
NOTE: The use of some
functions are mutually exclusive
67/
50
(x4)
67/
51
(x4)
67/
50N
(x4)
67/
50
(x4)
67/
50
(x4)
67/
51
(x4)
67/
51
(x4)
67/
51N
(x4)
67/
50G
(x4)
67/
51G
(x4)
67/
50S
(x4)
67/
51S
(x4)
64
H
27
59
27
59
(x4)
27
59
(x4)
27
59
(x4)
47
(x2)
81
(x6)
79
Optional
59N
(x2)
81
HBL
2N
60
VTS
51V
51V
51V
37G
(x2)
37S
(x2)
51c
60
CTS-
I
60
CTS-
I
60
CTS-
I
37
50
BF
37
50
BF
25
50
AFD
50
AFD
50
AFD
51c
51c
51c
Figure 2.8-1 Undercurrent
Voltage Inputs: n/a
Current Inputs: I
L1
(I
A
), I
L2
(I
B
), I
L3
(I
C
),
Disable: 51N, 51G, 46, 60CTS, 46BC
Map Pickup LED: 37-n - Self Reset
If two Undercurrent 37 elements are used with different settings, it is convenient to test the element with the
lowest setting first. The higher setting element can then be tested without interference from the other element.
Apply 3P balanced current at a level above the Undercurrent 37-n setting until the element resets.
If DTL setting is small, gradually reduce any each phase current in turn until element operates.
If DTL is large apply 1.1x setting, check for no operation, apply 0.9x setting, and check operation
Testing of this element phase by phase may cause inadvertent operation of the 46 NPS Overcurrent elements.
Apply 0.5x setting current and record operating time.