ABB RER620 - Troubleshooting; Event Overflow Handling; Overflow Mode; Overflow Indication Addresses

1MAC306892-MB C Section 3
Vendor-specific implementation
RER620 15
Communication Protocol Manual
•COT Length 
Should be set to 2. The standard requires COT Length set to 2 in both the master and
the slave devices.
• IOA Length

Usually, set to 3. This setting must have the same value in the master and slave
devices.
• Link Address Length

Usually set to 2. This setting must have the same value in the master and slave
devices.
• ASDU Address Length

Usually set to 2. This setting must have the same value in the master and slave
devices.
3.2.3 Troubleshooting
After setting the communication parameters correctly, check the communication.
• Use the communication card LED's to diagnose if the messages are properly
transmitted and received. There are diagnostic counters available in the protective
relay's Monitoring section.
• Check also that the other settings for the protocol instance match the master
configuration, as they affect the data interpretation.
3.3 Event overflow handling
3.3.1 Overflow mode
The protocol instance can be configured to keep either the newest or the oldest events in
case of buffer overflow. The event buffer overflows typically in a situation, where a lot of
signals change at the same time and the client is not able to fetch all the event reports
quickly enough. In these cases, the events that occurred in that critical moment are the
most important. It is recommended to use the keep oldest events mode. In addition, in this
mode the protective relay can be configured to generate an event buffer overflow
indication. After receiving overflow indication, the client can interrogate the protective
relay to ensure data integrity.
3.3.2 Overflow indication addresses
If the keep oldest events mode is enabled, the protective relay sends an event buffer
overflow indication. If the lost event is included in the interrogation list, the protective
relay sends the indication event with the address configured as "OvInd IOA". If the data is
not available for interrogation, the protective relay uses address configured as "OvInd
NoGI IOA". Both indications are sent if there are multiple events lost fulfilling both of the
criteria.