The programming of the autorecloser function SMBRREC determines if three-phase or single-phase
trip is initiated as result of the test.
Keep the current constant when measuring operating characteristics. Keep the current as close as
possible to its rated value or lower. But make sure it is higher than the set minimum operating
current.
Ensure that the maximum continuous current in an IED does not exceed four times its rated value, if
the measurement of the operating characteristics runs under constant voltage conditions.
To verify the mho characteristic, at least two points should be tested.
In the following, three test points are proposed. The mho characteristic always goes through the
origin, which automatically gives a fourth point for the characteristic.
11.4.3.1 Phase-to-phase faults
M14944-292 v8
ZAngPP
ZPP
1
23
Ohm/phase
R
X
IEC07000009-4-en.vsd
50%
IEC07000009 V4 EN-US
Figure 27: Proposed test points for phase-to-phase fault
Table 25: Test points for phase-to-phase (ohms / phase)
Test
points
reach Value Comments
1 X ZPP · sin(ZAngPP)
R ZPP · sin(ZAngPP)
2 X 0,5· (ZPP· sin(ZAngPP)
R 0,5·ZPP + ΔR = 0,5·ZPP·(1+cos(ZAngPP))
3 X 0,5·ZPP·sin(ZAngPP)
R 0,5·ZPP - ΔR = 0,5·ZPP(1-cos(ZAngPP))
Change the magnitude and angle of phase-to-phase voltage to achieve impedances at test points 1,
2 and 3. For each test point, observe that the output signals, START, STLx and STPP are activated
where x refers to the actual phase to be tested. After the timer tPP for the actual zone has elapsed,
also the signals TRIP, TRPP and TRx shall be activated.
Section 11 1MRK 505 378-UEN Rev. K
Testing functionality by secondary injection
106 Line differential protection RED670
Commissioning manual
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