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Chapter 6) 7SR17 Commissioning and Maintenance Guide
2.5
Undercurrent (37)
Voltage Inputs:
Current Inputs:
Disable:
Map Pickup LED:
Undercurrent Guard:
Undercurrent start:
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 3Phase balanced current at a level above the Undercurrent 37-n setting until the element resets. Check
operation with start option set to ANY phase and repeat with it set to operate for ALL phases.
If DTL setting is small, gradually reduce any 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
Apply 0.5x setting current and record operating time
Phase
Is
(Amps)
I
A
I
B
I
C
2.5.1.1
Element Blocking
The Undercurrent elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Page 22 of 62
n/a
I
, I
, I
,
A
B
C
14, 46, 48/66, 49, 50BF, 50, 50N, 51, 51N, 60CTS
37-n - Self Reset
As required
Any or ALL
DTL
P.U. Current
(sec)
Amps
Element
37-1
37-2
Tolerance
Operate Time
0.5 x Is
©2014 Siemens Protection Devices Limited
Tolerance
BI Inhibits
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