Application - ABB RELION REX640 Technical Manual

1MRS759142 C
10.2.6
REX640
Technical Manual
The time stamp for the ready 10-minute mean value calculation can be seen in
monitored data L time stamp.
The window type used for the 10-minute mean value calculation is always non-
sliding. The 10-minute value calculation begins based on the protection relay's
internal clock 10 minutes time (for example, 11:00, 11:10, 11:20, 11:30, 11:40, 11:50,
12:00...). This is called 10 min tick.
GUID-C467A4C0-7748-47CC-B168-E0AF0325FC3C V1 EN
Figure 834: The 10-minute interval with time synchronization and free running 3
seconds
The 10-minute mean value is shown in monitored data until the next 10-minute mean
value has been cumulated. Another 10-minute calculation can be started when time
synchronization is used to change the protection relay's internal clock. The first
calculation continues for 10 minutes and is then seen in the monitored data with a time
stamp. An event is sent every time a 10-minute value calculation is ready in the
monitored data.
See also the Time synchronization chapter in this document.
When the protection relay is powered on, the shown value is zero until the first 10-
minute mean value has been cumulated. During this time, the 10-minute output
quality is marked as bad in the IEC 61850 data.
Changing setting Sliding interval has influence on the seen mean values. Sliding
values change slowly towards the input value during the time interval. When mean
values have not been calculated for a full interval, quality is marked as bad in the IEC
61850 data. Bad quality is also indicated after the protection relay has been reset.

Application

Typically, the measured short-time 3-second mean values are used with a suitable
logic to give alarms. If a more stabilized value is needed, a 1-minute or 5-minute mean
value should be selected.
One example of using short-time mean values can be to compare the level of THD and
some harmonics, for example, 5
can be combined with MAX3R, and MAPGAPC can be used to test if the settable limit
Power quality measurement functions
th th
and 7 . The values to be compared to the same limit
Section 10
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