104
Current protection Chapter 11
Verifying settings by secondary
injection
If 2 of 3 currents for operation is chosen: Connect the injection current
into terminal L1 and out from terminal L2.
If 3 of 3 currents for operation is chosen: Connect the symmetrical 3
phase injection current into terminals L1, L2 and L3.
2. Connect the test set for the appropriate three-phase voltage injec-
tion to the IED terminals L1, L2 and L3. The protection shall be fed
with a symmetrical three phase voltage.
3. Set the injected polarizing voltage slightly larger than the set mini-
mum polarizing voltage (default is 5% of
Ur) and set the injection cur-
rent to lag the appropriate voltage by an angle of about 80
° if forward
directional function is selected.
If 1 of 3 currents for operation is chosen: The voltage angle of phase L1
is the reference.
If 2 of 3 currents for operation is chosen: The voltage angle of phase L1
– the voltage angle of L2 is the reference.
If 3 of 3 currents for operation is chosen: The voltage angle of phase L1
is the reference.
If reverse directional function is selected, set the injection current to lag
the polarizing voltage by an angle equal to 80
° + 180°.
4. Increase the injected current and note the operated value of the stud-
ied step of the function.
5. Decrease the current slowly and note the reset value.
6. If the test has been performed by injection of current in phase L1, re-
peat the test when injecting current into terminals L2 and L3 with po-
larizing voltage connected to terminals L2 respectively L3. (1 of 3
currents for operation)
7. If the test has been performed by injection of current in phases L1 –
L2, repeat the test when injecting current into terminals L2 – L3 and
L3 – L1 with appropriate phase angle of injected currents.
8. Block higher set stages when testing lower set stages according to
below.
9. Connect a trip output contact to a timer.
10. Set the injected current to 200% of the operate level of the tested
stage, switch on the current and check the time delay.
For inverse time curves, check the operate time at a current equal to 110%
of the operate current for tmin.
11. Check that all trip and start contacts operate according to the con-
figuration (signal matrixes)
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