6.1 Alarm Displays
6.1.2 Troubleshooting Alarms
6-25
A.C50:
Polarity Detec-
tion Failure
The parameter set-
tings are not correct.
Check the linear
encoder specifications
and feedback signal
status.
The settings of Pn282
(Linear Encoder Scale
Pitch) and Pn080 =
n.X (Motor Phase
Sequence Selection) may
not match the installa-
tion. Set the parameters
to correct values.
*1
There is noise on the
scale signal.
Check to make sure
that the frame grounds
of the Serial Converter
Unit and Servomotor
are connected to the
FG terminal on the SER-
VOPACK and that the
FG terminal on the SER-
VOPACK is connected
to the frame ground on
the power supply.
And, confirm that the
shield is properly pro-
cessed on the Linear
Encoder Cable. Check
to see if the detection
reference is repeatedly
output in one direction.
Implement appropriate
countermeasures against
noise for the Linear
Encoder Cable.
–
An external force was
applied to the Moving
Coil of the motor.
–
The polarity cannot be
properly detected if the
detection reference is 0
and the speed feedback
is not 0 because of an
external force, such as
cable tension, applied to
the Moving Coil. Imple-
ment measures to reduce
the external force so that
the speed feedback goes
to 0. If the external force
cannot be reduced,
increase the setting of
Pn481 (Polarity Detection
Speed Loop Gain).
–
The linear encoder
resolution is too low.
Check the linear
encoder scale pitch to
see if it is within 100
μm.
If the linear encoder scale
pitch is 100 μm or higher,
the SERVOPACK cannot
detect the correct speed
feedback. Use a linear
encoder scale pitch with
higher resolution. (We rec-
ommend a pitch of 40 μm
or less.) Or, increase the
setting of Pn485 (Polarity
Detection Reference
Speed). However,
increasing the setting of
Pn485 will increase the
Servomotor movement
range that is required for
polarity detection.
–
Continued on next page.
Continued from previous page.
Alarm Number:
Alarm Name
Possible Cause Confirmation Correction Reference
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