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Curve
IEC-LTI
ANSI-MI
ANSI-VI
ANSI-EI
Note that the operate time may be subject to the Minimum Op Time setting for the element and/or may
have a Follower DTL applied.
Element Blocking
The phase overcurrent elements can be blocked by Binary Input Inhibit, VT Supervision and
Inrush Detector operation, as well as 79 Delayed Inhibit setting. 79 inst elements are often config-
ured to be blocked by the autoreclose Out state using logic. If applicable this functionality should be checked.
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
51-1
51-2
51-3
51-4
50-1
50-2
50-3
50-4
ANSI Reset
If the element is configured as an ANSI characteristic, it may have an ANSI decaying reset delay applied.
ANSI reset times from operated condition to fully reset are as follows for zero applied current and Time multi-
plier (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) 2 times setting for a time to ensure element operation, b) Zero
current for the reset time above (xTm), c) 2 times 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
(expected)
Check correct indication, trip output, alarm contacts, waveform record.
IEC Reset
If the element is configured as an IEC characteristic, it may have an IEC decaying reset delay applied.
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
2 ⋅ I
set
120
3.8
7.03
9.52
BI Inhibits
VTS Action
Reset Time
Operate Time
(calculated)
(measured)
First test (c)
5 ⋅ I
set
30
1.69
1.31
1.3
81HBL2 Inhibit
Fully Operated to Reset with Zero Current Applied
& Tm = 1 (s)
4.85
21.6
29.1
50 % Reset Time
50 % Operate
(calculated)
Time (calcu-
lated)
Functional Tests
9.9 Protection Functional Tests
79 Delayed Inhibit
50 % Operate
Time (meas-
ured)
Second Test (c)
475
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