MTA Forward Reverse
Lag (point C) Lead (point A) Lead (point B) Lag (point D)
Pick-up Drop-off Pick-up Drop-off Pick-up Drop-off Pick-up Drop-off
MTA -85 MTA +85 MTA -85 MTA -85
Calculated
EF
Definite Time Overcurrent (50N)
If DTL setting is small, gradually increase current until element operates.
If DTL is large apply 0.9 times setting, check for no operation, apply 1.1 times setting, check operation.
Apply 2 times setting current if possible and record operating time.
Check correct indication, trip output, alarm contacts, waveform record.
Note that these elements can be set to directional.
Phase Dir. I
set
(Amps) DTL (sec) P.U. Current
Amps
Op. Time 2 ⋅
I
set
Notes
N
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 3P 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.
Inverse Time Overcurrent (51N)
It will be advantageous to map the function being tested to temporarily drive the relevant pickup output in the
Pickup Config sub-menu in the Output Config menu as this will allow the Pickup LED to operate for
the function.
Gradually increase current until Pickup LED operates.
Apply 2 times setting current and record operating time.
Apply 5 times setting current and record operating time.
Compare to calculated values for operating times.
Table 9-8
P.U. D.O. & Timing Tests
Ph. Dir Char.
(NI EI VI
LTI,
DTL)
I
set
(A) Tm Operate Current Operate Time
P.U.
(Amps)
D.O.
(Amps)
Tol 2 ⋅ I
set
(sec)
5 ⋅ I
set
(sec)
Tol
N
Calculated timing values in seconds for Tm = 1.0
Curve
2 ⋅ I
set
5 ⋅ I
set
IEC-NI 10.03 4.28
IEC-VI 13.5 3.38
IEC-EI 26.67 3.33
IEC-LTI 120 30
ANSI-MI 3.8 1.69
ANSI-VI 7.03 1.31
ANSI-EI 9.52 1.3
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.
Functional Tests
9.9 Protection Functional Tests
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 483
C53000-G7040-C014-1, Edition 11.2019
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