Operation Of Slow Open Ct Detection Algorithm - ABB REB670 Commissioning Manual

Section 10
Testing functionality by secondary injection
10.3.1.5
88
1. Connect the currents I1 and I2 from the three-phase test set test set to the
current terminals of CT1 and CTx inputs of the IED as shown in Figure 13.
2. Make sure that the current measurement from CT1 and CTx inputs are
included into the same differential zone (see the previous test instructions for
more details).
3. Set the current I1 (that is, current connected to input CT1) to the nominal
secondary value (normally 1A or 5A) at 0° see the formula (Equation 1) from
the previous section.
4. Set the current I2 (that is, connected to current input CTx) to the value
calculated by the formula (Equation 2) from the previous section.
5. Make sure there is enough current for fast open CT algorithm to operate,
when the current is disconnected later during testing, by checking that the
value of the product I2 × CTprimx is bigger than the value of the product 1.1
× OCTOperLev
6. Set the phase angle of the current I2 as explained in the previous section.
7. Inject these two currents into the IED for approximately 5s. Observe that the
differential function shall be stable. Write down the service values for
incoming and differential currents for phase L1. Observe that the differential
current should be very small.
8. Switch off the current I1 only (that is, set its magnitude back to 0A).
9. Check that open CT condition shall be detected by the IED, and the
differential function behavior shall be in accordance with the value of the
parameter FastOCTOper.
10. Check that open CT alarm contacts operate accordingly to the scheme wiring.
11. Check that open CT information is stored in the event list (if connected).
12. Switch off the currents.
13. Reset the open CT blocking in the reset menu of the local HMI.
14. Check that open CT reset information is stored in the event list (if connected).
15. Repeat the same test procedure for the phases L2 and L3.

Operation of slow open CT detection algorithm

For open CT test two current inputs shall be always used. Similar to the previous
section, the test will be explained for CT1 and CTx (2 ≤ x ≤ Nmax).
The connections are shown for phase L1 only. Similar connection shall be used for
testing phase L2 and L3 also. The typical connection between the three-phase
current test set and the IED for this type of tests is shown in Figure 13.
Follow the following test instructions to perform the test on the operation of slow
open CT detection:
1MRK 505 372-UEN A
SEMOD65871-3 v4
Busbar protection REB670 2.2 IEC
Commissioning manual