Operation Of Slow Open Ct Detection Algorithm - ABB Relion 670 Series Commissioning Manual

1MRK 505 372-UUS Rev. K
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 A.
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 B and C.
10.3.1.5

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 A only. Similar connection shall be used for testing phase B and C
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:
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).
4. Set the current I2(that is, connected to current input CTx) to the value calculate as follows:
I 2 0.85 CTsecx
IECEQUATION16067 V1 EN-US
Where
secondary current of the current input CTk, while the configuration parameter CTprimk represents
the rated primary current.
Busbar protection REB670
Commissioning manual
CTx
  
CT
CTprimk ,

CTk k
ratio
CTseck
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  
ratio
0.85 CTsec1
1
ratio
 or x
1
. The configuration parameter CTseck represents the rated
Testing functionality by secondary injection
CTprimx
,
CTprim1
Section 10
SEMOD65871-3 v4
(Equation 3)
75