Ansi Reset; Element Blocking - Siemens 7SR18 Solkor Manual

3.7.3
ANSI R
ESET
If the element is configured as an ANSI characteristic, it may have a reset delay applied. If ANSI reset is selected
for an IEC characteristic element, the reset will be instantaneous.
ANSI reset times from operated condition to fully reset are as follows for zero applied current and TM = 1.0. The
reset curve characteristic type and TM is defined by the operating characteristic.
Curve
ANSI-MI
ANSI-VI
ANSI-EI
Apply current in the following sequence, a) 2x setting for a time to ensure element operation, b) Zero current for
the reset time above (xTM), c) 2x setting for a time to ensure element operation. Check that the second operation
(c) is similar to the first (a) and in line with the expected operate time for the element at this current level.
Repeat the test with the reset time (b) reduced to 50 % of the previous value. Ensure that the second operate
time (c) is 50 % of the first (a) operate time.
Operate time Reset time
(expected) (calculated)
3.7.4
E B
LEMENT LOCKING
The NPS Overcurrent elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Element
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
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Fully operated to reset with Zero current applied & TM=1 (seconds)
Operate time
(measured)
First test (c)
46IT
46DT
7SR18 Commissioning & Maintenance Guide
4.85
21.6
29.1
50 % Reset 50 % Operate
Time time
(calculated) (calculated)
BI Inhibits
50 % Operate
time
(measured)
Second Test (c)
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