Undercurrent (37) - Siemens 7SR224 Technical Manual

2.10 Undercurrent (37)

I
(I /I
G
V
(V
V
(V
V
(V
(V
Figure 2-11 Undercurrent
Voltage Inputs:
Current Inputs:
Disable: 51N, 51G, 46, 60CTS, 46BC
Map Pickup LED:
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, 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
©2010 Siemens Protection Devices Limited
37 50
49
(x2) BF
I
L1
(I )
A
37 50
49
(x2) BF
I
L2
(I )
B
37 50
49
(x2) BF
I
L3
(I )
C
46
46 60
NPS
BC CTS
(x2)
67/
64
50G
H
4 (x4)
)
SEF
NOTE: The use of some
functions are mutually exclusive
27
27S
L1
59
) 59S
A
(x4)
27
27S
L2
59
) 59S
B
(x4)
27
27S
L3
59
) 59S
C
(x4)
V 27
4
) 59
X
n/a
I (I ), I (I ), I (I ),
L1 A L2 B L3 C
37-n - Self Reset
7SR224 Argus Commissioning & Maintenance Guide
7SR224
67/ 67/ 81
51V 50 51 HBL
(x4) (x4) 2
67/ 67/ 81
51V 50 51 HBL
(x4) (x4) 2
67/ 67/ 81
51V 50 51 HBL
(x4) (x4) 2
60
VTS
67/ 67/ 67/
51G 50S 51S
(x4) (x4) (x4)
Note:
Example shows
Voltage Config =
47
81 Van, Vbn, Vcn
(x2) (x4)
74
59N Batt
TCS
Test
(x2)
(x3)
Cap.
79
Test
Chapter 6 Page 38 of 73