P.3.315
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Protection Application Examples
designed to distinguish channel issues from relay issues. In particular, 87LSP
asserts when the 87L elements (including 87DTT) assert without the
disturbance detector also picking up. Relay Word bit 87LSP remains asserted
for three cycles, to coordinate with the 40 ms of post-trigger data from the
channel recorder files.
To enable write protection of the channel recording files, set 87CHWP = Y.
Setting 87CHWP = Y prevents any new 87L channel recorder files from being
generated once the relay used up all the memory allocated for the 150 channel
recorder files. Please note that testing the relay's 87L function without placing
the relay into test mode (see Test Mode on page P.11.4) can result in assertions
of the 87LSP Relay Word bit which then triggers the recording of 87L channel
recorder files. It is therefore good practice to clear the channel recorder files
when commissioning testing is complete and before putting the relay in
service. Channel recorder files are deleted by executing the COM 87L
FILES C (or COM 87L FILES R) command (see Table 15.31).
Protection Application Examples
This section provides detailed instructions for setting the SEL-411L Relay
protection functions. Use these application examples to help familiarize
yourself with the relay, and to assist you with your own protection settings
calculations. The settings that are not mentioned in these examples do not
apply.
Detailed setting calculation guidelines are provided for the following
applications:
➤ Two-Terminal 500 kV Line Differential Example
➤ Three-Terminal 345 kV Line Differential Example
Two-Terminal 500 kV
Line Differential
Example
Figure 3.218 shows a two-ended overhead 500 kV line with SEL-411L Relays
at each end. This example explains how to select settings for each relay.
Table 3.165 87L Channel Recorder Settings
Setting Description Range Default
87CHTRG 87L channel recorder trigger SELOGIC control
equation
87LSP
87CHWP Write protect for channel
recording files
Y, N N
NOTE: To ensure proper
communication and protection,
please refer to the firmware
compatibility in Table A.2.
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