Impulse no. 1 – 2010 (PDF) - Leine & Linde

TECHNICAL INFORMATION
Handling pulse encoder cables
When a pulse encoder is installed, attention must be paid to the fact that the
connection cables can only tolerate a certain level of stress. The cable specifications
must always match the requirements of the application. Cheap cables
often reduce system function and are seldom a good investment in the long run.
If cables are pulled, coiled, bent or subjected
to pressure they can be damaged.
Cables subjected to this kind of impact
should always be replaced.
Leine & Linde recommends that connection
cables for pulse encoders always
be laid in a separate cable duct. In combination
with other measures, this improves
the EMC properties for the entire
installation. If there is only one combined
cable duct available for signal and power
cables, the signal cables should be bundled
together and positioned as far away
as possible from power cables. There are
several advantages to separation:
Better EMC properties
Better protection from damage, for
example if bigger power cables are laid
in the same duct at a later point
Simpler fault tracing during maintenance.
If despite everything there is disturbance
from surrounding equipment, Leine &
Linde’s Optolink solution can always be
used. Transmitting pulse encoder signals
via an optical fibre cable eliminates the
risk of disturbance.
Unused cables in multiconductor
Cable conductors should always be
regarded as live, during installation as
well as when the system is operational.
Unused cables must therefore always be
insulated to prevent short circuits.
Mechanical damage to cabling
Pulse encoder cables should always be
laid in an earthed aluminium or steel
pipe when they are placed near to moving
machine parts. When the cable is laid,
particular care must always be taken to
ensure the cable is not subjected to mechanical
impact.
Storage and transport
During storage, transport and installation,
pulse encoder cables should be kept
sealed at both ends or be kept in their
protective packaging. This is to prevent
oxidation of the individual cables, their
shields and protective sheaths. It is also
important to prevent moisture collecting
in the cable.
Surrounding environment
If the pulse encoder’s stated maximum or
minimum temperature is exceeded, this
can damage the electrical or mechanical
properties of the cables. The temperature
readings for installed cables should
always match the temperature readings
for the pulse encoder at the installation
point. In flexible installations, where the
cable moves, the temperature readings
for the cable and the encoder may differ.
In such cases, always contact Leine &
Linde for more information about your
cable variant.
Elasticity
Cables should not be subjected to more
stretching than they can cope with during
handling and installation.
Pressure on cables
Always avoid pressure on the cable. This
can arise in connection with incorrect
installation.
Twisting / rotation of cable
Twisting or excessive rotation of the cable
can lead to destruction of the wires
or insulation of the cable. Cables should
therefore not be twisted unless they have
been specially designed for that purpose.
Bending radius
The cable’s permitted bending radius
must be maintained. Failing to do this
can lead to damage or to a reduction in
the transmission capabilities of the cable.
Please note that the permitted bending
radius is often higher when the cable
moves in its application than when it is
installed in a fixed position.
Loops
Try to ensure that the cable does not
form loops when it is installed in an application.
This can lead to poorer EMC
resistance and mechanical damage. The
cables must be installed without being
twisted. When you install the cables,
make sure that they cannot be subjected
to any unpermitted impact at a later
point once they
are installed.
Dirt, grease, oil and vibrations… An environment
that Leine & Linde’s encoders
are well able to cope with. The picture
shows the assembled product at one of
SSAB’s plants.
SSAB, a wor
Hans Bondegård, electrical engineer on
the format line, meets us at the gates to
the huge SSAB Borlänge plant in Sweden.
After we have been issued with visitors’
passes and protective clothing we drive
into the area. Here you don’t walk from
door to door; you have to drive around
this enormous area.
Hans has worked at
SSAB for 32 years,
and during our
visit it becomes
clear that he is
extremely knowledgeable
about
his field.
Hans shows us the
way in to the production line belonging to
the format line production section.
”Here thin plate is shaped according
to the customer’s request with regard to
thickness, width and length. The thinnest
plate is just 3 mm thick and the thickest
is around 16 mm. The raw material is
supplied in large coils in pre-determined
thicknesses, direct from SSAB’s rolling
mill,” explains Hans.
The format line produces around
350,000 tons a year and the staff work in
five shifts. Production never stops. The
whole process operates as a single line
and the department is therefore called
simply the format line. There’s hardly
anyone along the production line. Hans
laughs and points to a cabin. The staff sit
in there, controlling the whole work process
via monitors and control systems,
which explains the lack of people in the
area.
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