7SR210 & 7SR220 Commissioning & Maintenance Guide
© 2013 Siemens Protection Devices Limited Page 19 of 82
1.1.1.1 Element Blocking
The Phase Overcurrent elements can be blocked by Binary Input Inhibit, VT Supervision and Inrush Detector
operation, as well as 79 Autoreclose settings for Inst/Delayed. The Characteristic can be modified by Cold Load
(51-n only) and Voltage Controlled Overcurrent and can be made non-directional by VT Supervision. This
functionality should be checked.
Element BI Inhibits VTS action Inrush Detector 79 Autoreclose
51-1
51-2
51-3
51-4
50-1
50-2
50-3
50-4
.
2.1.1.1 ANSI Reset
If the element is configured as an ANSI characteristic, it may have an ANSI (decaying) 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 Time multiplier
(TM) = 1.0. The reset curve characteristic type and TM is defined by the operating characteristic.
Curve Fully operated to reset with Zero current applied & TM=1 (secs)
ANSI-MI 4.85
ANSI-VI 21.6
ANSI-EI 29.1
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.
Check correct indication, trip output, alarm contacts, waveform record.
Operate time
(expected)
Reset time
(calculated)
Operate time
(measured)
50% Reset
Time
(calculated)
50% operate
time
(calculated)
50% operate
time
(measured)
First test (c) Second Test (c)
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