SEFRAM 52 Manuel D'utilisation page 27

 Left rotary field
Firmly →
Testing of phase-sequence direction
is possible from 100V AC voltage (phase
to phase) provided the neutral is earthed.
On making contact with both test electrodes
(probe tips) to two phases of the three-phase
power supply which are connected in clock-
wise rotation, a "B" symbol appears in the
LCD Display.
If the rotation is anticlockwise, then a "C"
symbol is displayed. In this case both phases
of the unit should be switched around.
Testing the phase rotation always requires a
negative phase rotation test!
To ensure a connect test, it is better to test
on a known source.
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