7SR18 Commissioning & Maintenance Guide
Unrestricted ©2018 Siemens Protection Devices Limited Page 19
P/F Differential Setting (Secondary A)
Restraint Current (Secondary A)
Phase Reversal – Disabled No trip – Yes/No
Phase Reversal – Enabled Relay Trip – Yes/No
Phase Reversal – Disabled Relay Reset – Yes/No
Waveform record obtained Yes/No
Directional test results with feeder load current > P/f Bias Setting /2
*Note, for correct operation, when the Phase Reversal is activated both relays operate.
Often this test is conducted to operate the trip relay only, without tripping the feeder, by removal of the CB Trip -
Fuse and Link. For this test, the relay will be in permanent trip state. The relay does not accept setting changes
when in the tripped state, as the relay trip operation takes priority over implementing setting changes. To revert
the relay to its normal state, change the Phase Reversal setting(s) to normal and select “Update Changed
Setting” in the Relay Menu of Reydisp Evolution. Then remove the relay supply by extracting either its supply fuse
or link, to power the relay down. Immediately after the LCD powers down, power the relay up by re-inserting the
fuse or link. The setting change will then be implemented to and the Phase Reversal removed (set to Disabled) to
allow the relay to reset.
Test 2 – Where Load Current is Low
This test applies when the restraint current is below the P/F differential settings /2.
The connections are correct if the relay indicates an increase in differential current when the Phase Reversal
applied to one relay only. The Phase Reversal Setting is found in the CT/VT Config Menu. In this state, the
differential current should be approximately double the restraint current. The differential current should increase
significantly when Phase Reversal is implemented. Check the differential and restraint currents for all three
phases.
The Phase Reversal is implemented as described in Test No 1 above. The Phase Reversal should then be de-
selected.
P/F Differential Setting (Secondary A)
Restraint Current (Secondary A)
Phase Reversal – Disabled No trip – Yes/No
*Phase Reversal – Enabled Relay Trip – Yes/No
Phase Reversal – Disabled Relay Reset – Yes/No
Waveform record obtained (e.g. from status input
initiation)
Yes/No
Comparator tests with feeder load current< P/F Bias Setting/2.
If load current levels measured by the relay are very low then settings may have to be altered to allow the
increase in differential currents to be registered, when the Phase Reversal is applied.
P/F Differential Setting Selected
Secondary Current Required to activate Phase Reversal
Relay 1 Ampere Rated Inputs
used (mA)
used (mA)
0.10 x In
0.15 x In
0.20 x In
0.25 x In
0.30 x In
0.35 x In
0.40 x In
0.45 x In
0.50 x In
To Next Page
Loading...
