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Allen-Bradley PLCs
Connecting Your 1394 SERCOS Interface System
System Module Wire Sizes
All wire sizes in this manual are recommended minimums. Assume
that wires are type MTW copper wire (machine tool wire, 75° C,
minimum) per NFPA 79 unless otherwise noted. Consult the National
(or local) Electrical Code for factors related to ambient conditions,
length, etc. See your Allen-Bradley Sales Representative for more
information.
Shielding
To minimize radiated and induced noise problems or ground loops,
separate feedback, command, and other shields from each other and
connect them at a common machine or system earth ground. Connect
all shields to a single earth ground point. Refer to Grounding Your
1394 SERCOS interface System in this chapter and Appendix B for
additional information.
EMI/RFI Shielding
The 1394 has an inverter carrier frequency of 5000 Hz. The drive's
output inverter switching sequence produces a carrier frequency of
10,000 Hz when measured at the motor. This can induce noise into
sensitive equipment lines adjacent to it.
This system can produce electromagnetic radiation
ATTENTION
that can cause industrial or radio-controlled
equipment to operate erratically and cause possible
!
injury to personnel. The 1394 system is designed to
be interconnected with Allen-Bradley EMI shielded
motor cables only. Do not substitute cables. The EMI
shield of the motor power cable must be grounded at
both ends to function properly.
EMI/RFI Bonding
The metal chassis of electrical components should be bonded to the
subpanel in an electrical cabinet with metal to metal contact. The
purpose of a high frequency (HF) bond is to provide HF noise
currents a path of least impedance to return to their source.
2-3
Publication 1394-5.20 — July 2001
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