P341/EN AD/F43 Update Documentation
(AD) -28
MiCOM P341
Menu Text Default Setting Available Settings Function
Control Inputs Visible Invisible or Visible
Makes settings visible
in the relay menu
CLIO Inputs Enabled Enabled or Disabled
Enables protection
element in the relay
CLIO Outputs Enabled Enabled or Disabled “
Ctrl I/P Config Visible Invisible or Visible
Makes settings visible
in the relay menu
Ctrl I/P Labels Visible Invisible or Visible
Makes settings visible
in the relay menu
Direct Access Enabled Enabled or Disabled
Enables direct access
keys in the relay
LCD Contrast 11 0-31 LCD contrast setting
2.3 Phase rotation
2.3.1 Description
A facility is provided in the P341 to maintain correct operation of all the protection functions
even when the generator is running in a reverse phase sequence. This is achieved through
user configurable settings available for the four setting groups.
The default phase sequence for P341 is the clockwise rotation ABC. However, some power
systems may have a permanent anti-clockwise phase rotation of ACB.
In pump storage applications there is also a common practice to reverse two phases to
facilitate the pumping operation, using phase reversal switches. However, depending on the
position of the switches with respect to the VTs and CTs, the phase rotation may not affect
all the voltage and current inputs to the relay. The following sections describe some
common scenarios and their effects.
For pump storage applications the correct phase rotation settings can be applied for a
specific operating mode and phase configuration in different setting groups. The phase
configuration can then be set by selecting the appropriate setting group, see section 3.10 for
more information of changing setting groups. This method of selecting the phase
configuration removes the need for external switching of CT circuits or the duplication of
relays with connections to different CT phases. The phase rotation settings should only be
changed when the machine is off-line so that transient differences in the phase rotation
between the relay and power system due to the switching of phases don’t cause operation of
any of the protection functions. To ensure that setting groups are only changed when the
machine is off-line the changing of the setting groups could be interlocked with the IA/IB/IC
undercurrent start signals and an undervoltage start signal in the PSL.
2.3.1.1 Phase reversal switches affecting all CTs and VTs
The phase reversal affects all the voltage and current measurements in the same way,
irrespective of which two phases are being swapped. This is also equivalent to a power
system that is permanently reverse phase reversed.
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