Parker Hannifin
Appendix C Regulatory Compliance–UL and CE - 105 -
All braid termination connections must remain secure. For small
diameter cables, it may be necessary to fold back the braid or add
additional conductive material, such as conductive, adhesive, copper
tape to increase the effective diameter of the cable so that R-clamps are
secure.
Figure 43 360° Bonding Techniques
• Within the cabinet itself, all the motor cables should lie in the same
trunking as far as possible. Keep the cables separate from any low-level
control signal cables. This applies particularly where the control cables
are unscreened and run close to the drive/controller.
• A steel equipment cabinet will screen radiated emissions provided all
panels are bonded to a central earth point. Separate earth circuits are
commonly used within equipment cabinets to minimize the interaction
between independent circuits. A circuit switching large currents and
sharing a common earth return with another low-level signal circuit
could conduct electrical noise into the low level circuit, thereby possibly
interfering with its operation. For this reason, so called ‘dirty earth’ and
‘clean earth’ circuits may be formed within the same cabinet, but all
such circuits will eventually need to be returned to the cabinet’s main
star earth point.
• Mount the individual units and EMC filter on a metal earth plane. The
earth plane will have its own individual star point earth that should be
hard wired (using an insulated copper conductor) back to the cabinet’s
‘clean earth’ connection point.
• Panel mounting can provide a similar measure of EMC performance if
strict attention is paid to cable screen termination and cable layout.
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