Decentral Solutions
Decentralized cabling
The figure illustrates how the three-phase power
cable can be distributed with power looping from one
motor (drive) to the next. The cable saving potential is
illustrated in figure 4. Given a distance of 33 ft (10m)
between each motor and 66ft (20m) between each line,
the potential cable savings as a function of the number
of motors and number of lines shows of the figure.
Cable saving potential in an illustrative installation
The saving potential in power cable length alone
is substantial. The figure only illustrates the
potential concerning power cables. Issues like
unshielded/shielded cables and cable dimensions also
adds to the benefits of decentralized installations.
Real case
Calculations on a specific, typical bottling line with 91
pieces of 1.5 HP (1.5 kW) motors, taking the cable
dimensioning into account, showed the following
saving potential in cables and terminations:
•
Cable terminations are reduced from 455 to 352
•
EMC cable terminations are reduced from
364 to 182 by using motor controls with
integrated service switches
•
Power cable length reduced from 21,220 ft
(6468m) to 3870ft (1180m), a reduction of 17,350ft
(5288m), and it is converted from shielded cables
to standard installation cables
For details consult the following chapter on
Good installation practice
.
■
Minimal need for additional fieldbus cables
Power cable savings are not offset by the additional
cost for expensive fieldbus cables. Fieldbus cables
will be extended in a decentralized installation, but
since fieldbus cables will be distributed in the plant
anyway to connect sensors or remote I/O-stations,
the extension will be limited. Decentralized products
from Danfoss can even be used as remote I/O
MG.90.F2.22 - VLT is a registered Danfoss trademark
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