Rockwell Automation 865 Differential Protection Relay - Manual (Page 93)

Chapter
4
865-UM001A-EN-P – July 2009
Supporting Functions
Event Log Event log is a buffer of event codes and time stamps including date
and time. For example each start-on, start-off, trip-on or trip-off of
any protection stage has a unique event number code. Such a code
and the corresponding time stamp are called an event.
As an example of information included with a typical event an
overvoltage trip event of the first 59 stage U> is shown in the
following table.
Table 4.1 – Typical Overvoltage Trip Event
Event Description Local Panel
Communication
Protocols
Code: 30E2 Channel 30, event 2 Yes Yes
U> trip on Event text Yes No
112.0 %Ugn Fault value Yes No
2007-01-31 Date Yes Yes
08:35:13.413 Time Yes Yes
Type: U12,23,31 Fault type Yes No
Events are the major data for a control system. Control systems are
reading events using any of the available communication protocols.
Event log can also be scanned using the front panel or using
SetPointPS. With SetPointPS, the events can be stored to a file
especially in case the relay is not connected to any control system.
Only the latest event can be read when using communication
protocols or SetPointPS. Every reading increments the internal read
pointer to the event buffer. (In case of communication error, the
latest event can be reread any number of times using another
parameter.) On the local panel scanning the event buffer back and
forth is possible.
Event enabling/masking
There is room for 50 latest events in the event buffer. The oldest one
will be overwritten, when a new event does occur. The shown resolution
of a time stamp is one millisecond, but the actual resolution depends of
the particular function creating the event. For example most protection
stages create events with 10 ms or 20 ms resolution. The absolute
accuracy of all time stamps depends on the time synchronizing of the
relay. See page 4-11 for system clock synchronizing.
Events can be masked, which prevents their inclusion in the event
buffer.