ABB RED615 Technical Manual page 372

Section 4
Protection functions
366
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 IED 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 IED and sets the remote IED to a remote test mode, such
that the injected currents are echoed back with the shifted phase. It is also possible
that both IEDs are simultaneously in the test mode. When the line differential
protection function is in the test mode:
• The remote end IED echoes locally injected current samples back with the
shifted phase. The current samples that are sent to the remote IED 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 IED 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 IED which is in the test mode.
• The PROT_ACTIVE output is false only in the IED that is currently in the test
mode.
GUID-8E76712C-5DA3-46DA-AC6A-3C05CDBAB5AF V3 EN
Figure 192: Operation during the normal operation of the line differential
protection
1YHT530004D05 D
615 series
Technical Manual