Hitachi Relion REB670 Commissioning Manual page 150

Section 11
Primary injection testing
6. Check that trip information is stored in the disturbance recorder and event list (if connected).
7. Switch off the current.
8. Check the function in the same way by injecting current in phases L2 and L3.
It is recommended that each primary CB is tripped directly from the protection scheme at least once
during these tests. This will confirm the trip-circuit connection between the protection scheme and the
CB.
11.2 Stability of the busbar differential protection
For stability testing, one current circuit shall always be used as a reference input. The reference
current circuit shall then be tested for stability against all other current circuits connected to a busbar
protection scheme on a one-by-one basis. Use the current circuit connected to the CT1 current input
as the reference current circuit. A typical connection for the primary current test set for this type of
tests is shown in figure 24.
Primary Injection
Test Set
IEC05000307 V2 EN-US
Figure 24:
For this type of primary injection tests a suitable current source should be applied across the primary
windings of two CTs connected in series as shown in figure 24. The testing is normally done on one
phase at the time. The currents in the secondary winding of these CTs are then opposite in phase.
The differential current displayed by the IED should be negligible while the incoming current
displayed should be equal to the value of the injected primary current. The IED must not issue the
trip command during these tests. If it trips or the differential current has a high value it usually means
that there is a wiring problem in the CT circuits connected to the current input CTx (that is, a
differential current equal to twice the injection current probably indicates wrong polarity of the main
CT connected to the CTx current input). This problem must be solved before the protection scheme
is put in service.
Procedure
1. Connect the test set for primary current injection to the main CTs as shown in figure 24.
2. Make sure that current measurement from two used CT inputs are included in the same
differential zone.
3. Inject the primary current in phase L1 and note the incoming and differential currents on the
local HMI of the IED.
144
Typical test connection for primary injection, which should confirm the stability of
the main CT connected to current inputs of the IED
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1MRK 505 372-UEN Rev. K
REB 670
CT1 Current Input
CT2 Current Input
CT3 Current Input
CT4 Current Input
CT5 Current Input
IEC13000228-1-en.vsd
Busbar protection REB670
Commissioning manual
M12210-2 v5