DOC. MIE91093 Rev. 1.34 Page 44 of 145
1.5.3. MTA and angle sector
The first tests serve to measure the MTA and angle sector. We
will perform a threshold test by moving the test point on a
circle in the V-I plane.
TAKE CARE: φ1 is the angle at which you enter the operating area,
with the positive direction of angles; φ2 is the angle at which you leave
the operating area.
In the following are shown two cases: in the first one φ1 = 0°;
φ2 = 120°; MTA = 60°. In the second one φ1 = 240°; φ2 = 30°;
MTA = 315°.
. Set the “Automatic save at trip” function, as follows.
Test control > Save > Confirm at trip > ESC
. Select ON.
. Set: I = IN; V = VN; = MTA + 180°: the relay does not
trip.
. Slowly reduce the phase shift, until the relay trips: 1 trip is
found. As the relay trips, pressing the multi-function knob
tripping values can be saved. The TRIP LED (43) turns on for 5
seconds; during 5 seconds, parameters at trip are displayed;
then, the standard measurement is restored. Confirm save
results pressing the multi-function knob, and proceed: the
display shows the corresponding single-phase power.
. From this phase angle, slowly increase the phase shift, until
the relay resets: 1 drop-off is found. As the relay resets,
pressing the multi-function knob drop-off values can be
saved.
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