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2.33
Phase Rotation Reversal
A phase rotation feature via binary input and parameter is implemented in the 7UM61
device. This permits all protection and monitoring functions to operate correctly even
with phase rotation reversal, without the need for two phases to be reversed.
If an anti-clockwise rotating phase sequence permanently exists, this should be
entered in the power system data (see Section 2.3).
If phase rotation reverses during operation (e.g. in a pumped storage power station
transition from generator to pumping operation is done by changing the phase rota-
tion), then a reversal signal at the input allocated is sufficient to inform the protection
device of phase-sequence reversal.
2.33.1 Functional Description
Phase rotation is continually set by a Power System Data parameter at address 271
Logic
PHASE SEQ.. Binary input ">Reverse Rot." sets the phase rotation to the opposite
of the parameter setting.
Figure 2-76
For safety reasons, the device accepts phase rotation reversal only when no usable
measured quantities are current. The binary input is scanned only if operational con-
dition 1 is not current. If a reverse command is present for at least 200 ms, the mea-
sured quantities of phases L2 and L3 are exchanged.
If operational condition 1 is reached before the minimum control time of 200 ms has
expired, phase rotation reversal does not become effective.
As no phase rotation reversal is possible in operational condition 1, the control signal
could be retracted in operational condition 1 without a phase rotation occurring. For
safety reasons, the control signal should be permanently present in order to avoid mal-
functions also on device reset (e.g. due to configuration change).
7UM61 Manual
C53000-G1176-C127-3
Message logic of the phase-sequence reversal
2.33 Phase Rotation Reversal
201
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