20
TB MRU3-2 12.00 E
<SELECT>
<SELECT>
<SELECT>
<ENTER>
|SEG
TRIP
<SELECT>
<SELECT>
<ENTER>
<SELECT>
Display after tripping
Display in normal operation
Tripping
<RESET>
Measuring data
Parameter
Parameter
Failure data
Figure 1.1: Switching over of the display in dependence of the operating mode.
5.7.5
Indication of the phase sequence
The indication refers to the designation of the voltage
input terminals. The sequence can be "123" or "321".
Which phase sequence is the correct one depends
upon the given case of application. But in any case
the assignment has to be met which phase sequence
shall correspond to the positive sequence system.
Display "123" means that the connected rotating field
has the positive sequence system of unit
MRU3-2
and
thus is considered as correct. If these voltages are ad-
ditionally symmetrical, there will be no negative se-
quence system and the positive sequence system has
the same rms value as the phase voltages.
If the phase sequence "321" is indicated the assign-
ment could be wrong. This has to be checked whether
the applied voltages show a wrong phase sequence
or whether there is a fault in the connection. When
"???" is indicated the unit signalizes that no clear
measurement of the phase sequence is possible.
