Table of Contents
Advertisement
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)
Element Blocking
The NPS overcurrent elements can be blocked by Binary Input Inhibit. This functionality should be
checked.
Element
46IT
46DT
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
9.9.8
46BC Broken Conductor Detection
Broken conductor uses the ratio of NPS current to PPS current to detect an open circuit conductor . These
quantities can be produced directly from many advanced test sets but with limited equipment the following
approach can be applied.
Apply 3P balanced current with normal phase rotation direction. This current will consist of PPS alone, no NPS
or ZPS. Increase 1 phase current magnitude in isolation to produce NPS. The single phase unbalance current
will contain equal quantities of ZPS, NPS and PPS. The NPS component will be 1/3 of the unbalance current
and the total PPS component will be value of the original balanced 3P current plus 1/3 of the additional unbal-
ance current. i.e. as the single phase unbalance current increases, the ratio of NPS to PPS will also increase.
The levels of each sequence component current can be monitored in the Current Meters in Instruments
mode.
Inject 1 A of balanced current. Gradually increase imbalance current, operating level should be as follows:
46BC Setting
20 %
25 %
30 %
35 %
40 %
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
Reset Time
Operate Time
(calculated)
(measured)
First test (c)
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)
BI Inhibits
1P Unbalance Current (% of 3P current)
75 %
100 %
129 %
161 %
200 %
Functional Tests
9.9 Protection Functional Tests
50 % Operate
Time (meas-
ured)
Second test (c)
471
Advertisement
Table of Contents
