Eaton XC-CPU101 Series, Instruction Leaflet

Page: 35 / 96

12/14 MN05003004Z-EN
17
2 Engineering
Control panel layout
The layout of the components inside the control panel is a major
factor for achieving interference-free functioning of the plant or
machinery. During the project planning and design phase, as well
as its implementation, care must be taken that the power and
control sections are separated. The power section includes:
• Contactors,
• Coupling/interfacing components,
• Transformers,
• Frequency inverters,
• Converters.
In order to effectively exclude any electromagnetic contamination,
it is a good idea to divide the system into sections, according to
their power and interference levels. In small switchgear cabinets it
is often enough to provide a sheet steel dividing wall, to reduce
interference factors.
Ventilation
In order to ensure sufficient ventilation a minimum clearance of
50 mm to passive components must be observed. If the
neighbouring components are active elements, such as power
supplies or transformers, then the minimum spacing should be
75 mm. The values that are given in the technical data must be
observed.
Layout of units
Build the module racks and the controls into the switchgear
cabinet in a horizontal position:
Preventing interference
Cable routing and wiring
Cables are divided into the following categories:
• Electric power lines (e.g. power lines carrying high currents, or
lines to converters, contactors, solenoid valves)
• Control and signal cables: (e.g. digital input lines)
• Measurement and signal cables (e.g. fieldbus connections)
Take care to implement proper cable routing both inside and
outside the control panel, to keep interference as low as possible:
X
Avoid parallel routing of sections of cable in different power
categories.
X
As a basis rule, keep AC cable separated from DC cables.
X
Keep to the following minimum spacing:
– at least 10 cm between power cables and signal cables;
– at least 30 cm between power cables and data or analog
cables.
– When routing cables, make sure that the outgoing and return
leads of a circuit pair are routed together: The currents
flowing in opposite directions thus cancel each other out as
a summation. The generated electromagnetic fields cancel
each other out.
Suppressor circuitry for interference sources
X
All suppressor circuitry should be wired in as close to the source
of interference (contactors, relays, solenoids) as possible.
Shielding
X
Use shielded cables for the connections to the data interfaces.
The general rule is: the lower the coupling impedance, the
better the shielding effect.
Figure 17: Control panel layout
a Spacing > 50 mm
b
Spacing > 75 mm to active elements
c Cable duct
c
b a
b a
b
a
b
a
h Always route power cables and control cables as far apart
as possible. This avoids capacitive and inductive coupling.
If separate routing is not possible, then the first priority
must be to shield the cable responsible for the
interference.
h Switched inductors should always have suppressor
circuitry fitted.