128 - 23/May/97
It is not necessary to shield the input power wires, the bus bars, the flat cables between the
modules.
REMARKs:
- the shields of cables inside the cabinet
must be 360
°
clamped to the cabinet wall
(see Fig. 6.6).
- "noisy" cables must be kept away from
"sensitive" cables by at least 30 cm (12 in).
Noisy cables include input-power wires,
motor power and brake wiring. Sensitive
cables include analog or digital signal
cables: resolver cable; reference, enable
and OK cable; RS485 serial link; simulated
encoder wiring.
- where noisy cables must cross power
cables, this must be done with angles as
near to 90
°
as possible.
FIG. 6.7 - PARTITION PENETRATION
- the crossing of the cabinet should be
accomplished with a low impedance
connection between cable shield and
enclosure. If a connector is not involved,
the shortest practical lengths of connecting
strap should be used (see Fig.6.7).
6.4 RECOVERY RESISTOR / MOTOR CHOKE
To meet the Machinery Directive "the ventilated enclosures containing dynamic braking
resistors shall provide a degree of protection of at least IP22" (EN 60204-1, par. 13.3).
To meet the EMC Directive, these enclosures must be conductive. The cable of recovery
resistor must be shielded and the shield must be 360
°
clamped at both sides.
In some applications (e.g. some size 3 FAS T motors) a choke in series for each motor
phase has to be added. This choke must be shielded.
REMARK: when mounting the enclosure of recovery resistor or motor choke to the panel, it
is essential that any paint or other covering material be removed before mounting the
enclosure of recovery resistor or motor choke.
FIG. 6.6 - CLAMPING TO CABINET
Backpanel
(earth)
Screen is effectively
earthed 360
°
of its
radius
Cable Shield
Strap
Enclosure
Hex Head
Bolt
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