Stability Of The Busbar Differential Protection - ABB REB670 Commissioning Manual

Section 11
Primary injection testing
11.2
162
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 L1 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.
4. Check that the current is present only in the phase being tested.
5. If the injected current is high enough, check that trip contacts operate
accordingly to the scheme wiring.
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.

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.
1MRK 505 372-UEN A
M12210-2 v5
Busbar protection REB670 2.2 IEC
Commissioning manual