Siemens 7SR51 - 46 Negative Sequence Overcurrent Protection

Check correct phase indication, trip output, alarm contacts, waveform record.
46 Negative Sequence Overcurrent Protection
Where 2 NPS elements are being used with different settings, it is convenient to test the elements with the
highest settings first. The elements with lower settings can then be tested without disabling the lower
settings. The thermal withstand limitations of the current inputs, stated in the Technical Data should
always be observed during testing.
NPS overcurrent can be tested using a normal 3P balanced source. 2 phase current connections should be
reversed so that the applied balanced 3P current is negative phase sequence.
If Phase Rotation ACB is selected in the CT/VT menu, the expected PPS and NPS are exchanged and the
output from a standard positive sequence test set will be considered as NPS.
Definite Time NPS Overcurrent (46DT)
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.
Phase I
set
(Amps) DTL (sec) P.U. Current
Amps
Tolerance Operate Time
2 ⋅ I
set
Tolerance
NPS
Check correct indication, trip output, alarm contacts, waveform record.
Inverse Time NPS Overcurrent (46IT)
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.
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
NPS
Calculated timing values in seconds for Tm = 1.0
Curve
2 ⋅ I
set
5 ⋅ I
set
IEC-NI 10.03 4.28
IEC-VI 13.50 3.38
IEC-EI 26.67 3.33
IEC-LTI 120.00 30.00
ANSI-MI 3.80 1.69
ANSI-VI 7.03 1.31
ANSI-EI 9.52 1.30
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.
9.9.7
Functional Tests
9.9 Protection Functional Tests
470 Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019