ABB Relion 670 Series Commissioning Manual page 155

1MRK 505 372-UUS Rev. K
Section 11
A test with primary current through the protected zone is usually a final check that the current circuits are
correctly connected to the IED protection scheme. It is important to have an appropriate source, which is
able to inject sufficient current in the primary circuit in order to distinguish between noise and real
injected current. Therefore it is recommended that the injection current should be at least 10% of rated
CT primary current.
11.1 Operation of the busbar differential protection
The primary injection tests of a differential IED consist of applying a suitable current source across the
primary winding of the CT connected to the current input of the IED. The testing is normally carried out
on one phase at a time. If the primary current is bigger than the set value of the DiffOperLevel
parameter, the IED shall issue the trip command as well. The primary current injection test should be
repeated for every CT until all current circuits in all phases are checked. The typical connection for the
primary injection test is shown in figure 23.
Primary Injection
Test Set
ANSI05000470 V2 EN-US
Figure 23:
Testing will be explained from one general current input CTx (that is, x = 1, 2,..., Nmax; where Nmax is
equal to the maximum number of used CT inputs).
Follow the following test instructions for all used current inputs in an IED.
Procedure
1. Connect the test set for injection primary current to the main CT connected to the current terminals
of CTx input of the IED as shown in figure 23.
2. Make sure that current measurement from the CTx input are included in one of the differential
zones.
3. Inject the primary current in phase A and note the incoming and differential currents on the local
HMI of the IED. The values of the incoming and the differential currents shall correspond to the
injected primary current.
Busbar protection REB670
Commissioning manual
Primary injection testing
Whenever it becomes necessary to work on primary equipment, it is essential that all the
necessary switching, locking, grounding and safety procedures are observed and
obeyed in a rigid and formalized manner. Operating and testing procedures should be
strictly followed in order to avoid exposure to live equipment.
52
1200/5
Optional equipment
(i.e,Test Switch,CB
Fail relay,other relays)
Typical test connection for primary injection testing
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IED
CT Input
ANSI05000470-2-en.vsd
Section 11
Primary injection testing
IP10812-1 v1
SEMOD65857-3 v3
SEMOD65857-8 v2
M12203-3 v5
149