YASKAWA SGD7S series Product Manual page 180

Alarm Number:
Possible Cause
Alarm Name
The parameter set-
tings are not correct.
There is noise on the
scale signal.
A.C50:
Polarity Detec-
tion Failure
An external force was
applied to the Moving
Coil of the motor.
The linear encoder
resolution is too low.
Confirmation
The settings of Pn282
(Linear Encoder Scale
Check the linear Pitch) and Pn080 =
encoder specifications n.X (Motor Phase
and feedback signal Sequence Selection) may
status. not match the installa-
tion. Set the parameters
to correct values.
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- Implement appropriate
VOPACK is connected countermeasures against
to the frame ground on noise for the Linear
the power supply. Encoder Cable.
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.
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).
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-
Check the linear
ommend a pitch of 40 μm
encoder scale pitch to
or less.) Or, increase the
see if it is within 100
setting of Pn485 (Polarity
μm.
Detection Reference
Speed). However,
increasing the setting of
Pn485 will increase the
Servomotor movement
range that is required for
polarity detection.
9.1 Alarm Displays
9.1.2 Troubleshooting Alarms
Continued from previous page.
Correction Reference
*1
–
–
–
Continued on next page.
9
9-27