3.1 Main Circuit Wiring
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3.1.4
General Precautions for Wiring
To ensure safe, stable application of the servo system, observe the following precautions when wiring.
• Use the cables specified in the multi-winding drive unit catalog. Design and arrange the system so that each
cable will be as short as possible.
• Use shielded twisted-pair cables or screened unshielded twisted-pair cables for I/O signal cables and
encoder cables.
• Use the busbars that are included with the converter and connect the P and N terminals on the SERVOPACK
and converter securely.
• The maximum wiring length is 3 m for I/O signal cables, 50 m for servomotor main circuit cables and
encoder cables, and 10 m for the control power supply cables (+24 V and 0 V).
• Observe the following precautions when wiring the ground.
• Use a cable as thick as possible (at least 2.0 mm
2
).
• Ground the SERVOPACKs and converters to a resistance of 10
Ω
or less.
• Be sure to ground at only one point.
• Ground the servomotor directly if the servomotor is insulated from the machine.
• The signal cable conductors are as thin as 0.2 mm
2
or 0.3 mm
2
. Do not impose excessive bending force or
tension.
• Use a molded-case circuit breaker (1QF) or fuse to protect the main circuit.
The SERVOPACKs and converters connect directly to a commercial power supply;
They are not isolated through a transformer or other device.
Always use a molded-case circuit breaker (1QF) or fuse to protect the servo system
from accidents involving different power system voltages or other accidents.
• Install a ground fault detector.
The multi-winding drive unit, SERVOPACKs, and converters do not have a built-in
protective circuit for grounding.
To configure a safer system, install a ground fault detector against overloads and
short-circuiting, or install a ground fault detector combined with a molded-case circuit
breaker.
• Do not turn the power ON and OFF more than necessary.
• Do not use a multi-winding drive unit, SERVOPACK, or converter for applications
that require the power to turn ON and OFF frequently. Such applications will cause
elements in the multi-winding drive unit, SERVOPACK, or converter to deteriorate.
• As a guideline, at least one hour should be allowed between the power being
turned ON and OFF once actual operation has been started.