Sel 411L - 87 L Standby Channel Switchover Logic; Table 3.156 87 L Channel Monitoring Analog Quantities

P.3.297
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
87L Standby Channel Switchover Logic
87L Standby Channel Switchover Logic
This section applies only to two-terminal applications over a redundant serial
channel (E87CH = 2SD).
In the 2SD configuration, the relay uses the remote currents from the channel
indicated by the 87PCH setting as long as this channel is working, provides
high quality data synchronization, and switches over upon problems with the
primary channel to the other channel if the other channel is working and has
better synchronization quality. The 87HSB Relay Word bit controls
switchover (if 87HSB is deasserted, the relay uses the 87PCH channel.
Otherwise, the relay uses the other channel) as Figure 3.208 shows.
Note that the switchover occurs for the raw current samples, potentially
causing a disturbance in such scheme components as filtered currents,
magnitudes, and sequence components. As a result, the relay applies proper
security to the 87L function for a brief period following the switchover.
87CH2OK 87L Channel 2 is receiving valid data
87CH3OK 87L Channel 3 is receiving valid data (Ethernet only)
87CH1AL Alarm asserted for the 87L Channel 1
87CH2AL Alarm asserted for the 87L Channel 2
87CH3AL Alarm asserted for the 87L Channel 3 (Ethernet only)
a
Available if both relays are connected to a valid time source and are configured to operate in
time-based data synchronization mode (87CHpSN = T).
Table 3.156 87L Channel Monitoring Analog Quantities
Name Description Units
87CH1RT Round-trip delay for the 87L serial Channel 1 ms
87CH2RT Round-trip delay for the 87L serial Channel 2 ms
87CH1AX Asymmetry in the 87L serial Channel 1
a
a
Available if both relays are connected to a valid time source and are configured to operate in
time-based data synchronization mode (87CHpSN = T).
ms
87CH2AX Asymmetry in the 87L serial Channel 2
a
ms
87CH1LX Lost packet count among the scheduled 10,000 packets for
the 87L Channel 1
–
87CH2LX Lost packet count among the scheduled 10,000 packets for
the 87L Channel 2
–
87CH3LX Lost packet count among the scheduled 10,000 packets for
the 87L Channel 3 (Ethernet only)
–
87CH1LD Lost packet count in the last 24h for the 87L Channel 1 –
87CH2LD Lost packet count in the last 24h for the 87L Channel 2 –
87CH3LD Lost packet count in the last 24h for the 87L Channel 3
(Ethernet only)
–
Table 3.155 87L Channel Alarm Relay Word Bits (Sheet 2 of 2)
Name Description