The Illustration 1.4 shows how the three-phase mains cable can be dis-
tributed with power looping from one motor (drive) to the next. The cable
saving potential is illustrated in Illustration xx. Given a distance of 10 m
between each motor and 20 m between each line, the potential cable
savings as a function of the number of motors and number of lines shows
of the figure.
Illustration 1.4: Cable saving potential in an illustrative in-
stallation
The saving potential in power cable length alone is substantial. The figure only illustrates the potential concerning power cables. Issues like unscreened/
screened cables and cable dimensions also ads to the benefits of decentralised installations.
Real case
Calculations on a specific, typical bottling line with 91 pieces of 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 6468m to 1180m, a reduction of 5288m, and it is converted from screened cables to standard installation
cables
For details consult the following chapter on
Good installation practice
.
1.2.2 Design Savings
End users want to postpone the final decision for new equipment - and to start production as fast as possible once a decision has been made. Payback
time and time to market must be reduced. This squeezes both the design phase and the commissioning phase.
Modularisation can minimise lead-time. Even manufacturers of large production equipment or lines use modularisation to reduce lead-time. Up to 40-50
% on the total time from design to running production can be saved.
The concept of modularisation is known from equipment like PC’s and cars. Modules with well-described functionalities and interfaces are used in these
products. The same concept can be applied to manufacturing, even though specific physical constraints play a role.
1 The Decentral Concept
VLT
®
Decentral FCD 300 Design Guide
8
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
1
