5.9 Polarity Detection
5.9.1 Restrictions
5-24
5.9
Polarity Detection
If you use a Linear Servomotor that does not have a polarity sensor, then you must detect the
polarity.
Detecting the polarity means that the position of the electrical phase angle on the electrical
angle coordinates of the Servomotor is detected. The SERVOPACK cannot control the Servo-
motor correctly unless it accurately knows the position of the electrical angle coordinate of the
Servomotor.
The execution timing and execution method for polarity detection depend on the encoder
specification as described in the following table.
5.9.1
Restrictions
Assumed Conditions
The Servomotor will move when you execute polarity detection. The following conditions must
be met before you start.
•
It must be OK to move the Moving Coil about 10 mm.
(If polarity detection fails, the Moving Coil may move approximately 5 cm. The amount of
movement depends on conditions.)
•
The linear encoder pitch must be 100
μ
m or less. (We recommend a pitch of 40
μ
m or less
for an incremental encoder.)
•
As much as possible, the motor must not be subjected to an imbalanced external force. (We
recommend 5% or less of the rated force.)
•
The mass ratio must be 50x or less.
•
The axis must be horizontal.
•
There must be friction equivalent to a few percent of the rated force applied to the guides. (Air
sliders cannot be used.)
Preparations
Always check the following before you execute polarity detection.
•
Not using a polarity sensor must be specified (Pn080 = n.
1).
•
The servo must be OFF.
•
The main circuit power supply must be ON.
•
There must be no hard wire base block (HWBB).
•
There must be no alarms except for an A.C22 alarm (Phase Information Disagreement).
Encoder Specification
Polarity Detection Execution Timing
Polarity Detection Execution Method
Incremental encoder
Each time the control power supply to
the SERVOPACK is turned ON
(Even after you execute polarity detec-
tion, the position of the polarity will be
lost the next time the control power
supply to the SERVOPACK is turned
OFF.)
•
Use the /S-ON (Servo ON) signal.
•
Use the polarity detection function of
the S.
•
Execute the Fn080 (Polarity Detection)
utility function from the Digital Opera-
tor.
Absolute encoder
Only for initial setup, or after the
SERVOPACK, linear encoder, or
Servomotor has been replaced
(The results of polarity detection is
stored in the absolute encoder, so the
polarity position is not lost when the
control power supply is turned OFF.)
•
Use the polarity detection function of
the S.
•
Execute the Fn080 (Polarity Detection)
utility function from the Digital Opera-
tor.
If you use a Linear Servomotor that does not have a polarity sensor, you will not be able to
turn ON the servo until polarity detection has been completed.
Information
