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Functional Tests
9.9 Protection Functional Tests
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.
If VTS action is set to Block, this option should be tested. Apply balanced voltage and current. Reduce a-
phase voltage to cause a VTS condition. Increase a-phase current and check that the element does not
operate.
If VTS action is set to Non-Directional, this option should be tested. Apply balanced voltage and current.
Reduce a-phase voltage to cause a VTS condition. Increase a-phase current and check that the element oper-
ates at its normal setting. Reverse the voltage phase direction whilst checking that the element does not reset.
Element Blocking
The Measured Earth Fault elements can be blocked by Binary Input Inhibit, VT Supervision
and Inrush Detector operation. The characteristic can be made non-directional by VT Supervision.
This functionality should be checked.
Element
51G-1
51G-2
51G-3
51G-4
50G-1
50G-2
50G-3
50G-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 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.
IEC 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.
478
BI Inhibits
Reset Time
Operate Time
(calculated)
(measured)
First test (c)
VTS Action
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)
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
81HBL2 Inhibit
50 % Operate
Time (meas-
ured)
Second Test (c)
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