ABB RELION REX640 Technical Manual page 581

1MRS759142 C
REX640
Technical Manual
output is updated according to the BLOCK input status, as described in the Fail safe
function chapter.
The BLOCK and BLOCK_LS input statuses affect only the behavior of the local
protection instance. When a line differential protection stage (stabilized low or
instantaneous high) is blocked, also the received remote signals related to the
corresponding stage are ignored (received direct inter-trip signals from the remote
end). The binary signal transfer functionality should therefore be used for transferring
the possible additional blocking information between the local and remote terminals
whenever the blocking logic behavior needs to be the same on both line ends.
Test mode
The line differential function in one protection relay can be set to test mode, that is, the
Operation setting is set to "test/blocked". This blocks the line differential protection
outputs in the protection relay and sets the remote protection relay to a remote test
mode, such that the injected currents are echoed back with the shifted phase. It is also
possible that both protection relays are simultaneously in the test mode. When the line
differential protection function is in the test mode:
• The remote end protection relay echoes locally injected current samples back
with the shifted phase. The current samples that are sent to the remote protection
relay are scaled with the CT ratio correction setting.
• The operation of both stages (stabilized low or instantaneous high) are blocked,
and also the direct inter-trip functionality is blocked (both receive and send) in the
protection relay where the test mode is active.
• The remote end line differential protection function that is in the normal mode
(On) is not affected by the local end being in the test mode. This means that the
remote end function is operative but, at the same time, it ignores the received
current samples from the other end protection relay which is in the test mode.
• The PRO_ACTIVE output is false only in the protection relay that is currently in
the test mode.
GUID-95B82A23-B6DB-440F-9789-7E58E8266AB1 V1 EN
Figure 316: Operation during the normal operation of the line differential
protection
Section 4
Protection functions
575