ABB RELION REX640 Technical Manual page 587

1MRS759142 C
REX640
Technical Manual
When injecting current to one phase in the local end protection relay, the current is
seen as a differential current at both ends. If a current I
L1, the differential and stabilizing currents for phase L1 are:
ID A I
_
=
injected
GUID-516856A6-6D5B-41E2-BC85-E422B44749BA V1 EN
I
injected
IB A _
=
2
GUID-26FC00E0-F291-47FA-8273-C59AD1FB375A V1 EN
The operation is equal for phases L2 and L3.
Verifying the settings
1. Block the unwanted trip signals from the protection relay units involved.
2. Inject a current in phase L1 and increase the current until the function operates
for phase L1.
The injected operate current corresponds to the set Low operate value. The
monitored values for ID_A should be equal to the injected current.
3. Repeat point 2 by current injection in phases L2 and L3.
4. Measure the operating time by injecting the single-phase current in phase L1.
The injected current should be four times the operating current. The time
measurement is stopped by the trip output from the protection relay unit.
5. Disconnect the test equipment and reconnect the current transformers and all
other circuits including the trip circuit.
Phasor echoing method
The line differential function in one protection relay can be set to special test mode,
that is, the Operation setting is set to "test/blocked". When this mode is in use, the
remote end protection relay echoes locally injected current phasors back with the
shifted phase and settable amplitude. Therefore, the local end line differential function
is also automatically blocked and the remote end line differential function discards the
phasors it receives from the protection relay in the test mode.
When the test mode is active, the CT connection type is still used by the line
differential protection function as in the normal operation mode. The setting can be
used for shifting the phase (0 or 180 degrees).
Section 4
Protection functions
is injected, L1 in phase
injected
(Equation 101)
(Equation 102)
581