YASKAWA SGD7S Product Manual page 438

12.2 Alarm Displays
12.2.2 Troubleshooting Alarms
Alarm Number:
Alarm Name
A.C90:
Encoder Commu-
nications Error
A.C91:
Encoder Commu-
nications Posi-
tion Data
Acceleration Rate
Error
12-32
Possible Cause
There is a faulty con-
tact in the connector
Check the condition of
or the connector is
the encoder connector.
not wired correctly for
the encoder.
There is a cable dis-
connection or short-
circuit in the encoder. Check the condition of
Or, the cable imped- the Encoder Cable.
ance is outside the
specified values.
One of the following
has occurred: corro-
sion caused by
improper tempera-
ture, humidity, or gas,
Check the operating
a short-circuit caused
environment.
by entry of water
drops or cutting oil, or
faulty contact in con-
nector caused by
vibration.
A malfunction was
–
caused by noise.
A failure occurred in
–
the SERVOPACK.
Noise entered on the
signal lines because Check the condition of
the Encoder Cable is the Encoder Cable and
bent or the sheath is connectors.
damaged.
The Encoder Cable is
bundled with a high- Check the installation
current line or condition of the
installed near a high- Encoder Cable.
current line.
There is variation in
the FG potential
Check the installation
because of the influ-
condition of the
ence of machines on
Encoder Cable.
the Servomotor side,
such as a welder.
Confirmation
Reconnect the encoder
connector and check the
encoder wiring.
Use the Encoder Cable
within the specified speci-
fications.
Improve the operating
environmental, and
replace the cable. If the
alarm still occurs, replace
the SERVOPACK.
Correct the wiring around
the encoder by separating
the Encoder Cable from
the Servomotor Main Cir-
cuit Cable or by ground-
ing the encoder.
Connect the Servomotor
to another SERVOPACK,
and turn ON the control
power supply. If no alarm
occurs, the SERVOPACK
may be faulty. Replace the
SERVOPACK.
Check the Encoder Cable
to see if it is installed cor-
rectly.
Confirm that there is no
surge voltage on the
Encoder Cable.
Properly ground the
machine to separate it
from the FG of the
encoder.
Continued from previous page.
Correction Reference
page 4-26
–
page 3-2
page 4-6
–
page 4-9
–
–
Continued on next page.