Project Planning; Important Information; Drive Train Design; Energy Management - Beckhoff AX8000 System Manual

11

Project planning

11.1

Important information

The more thoroughly a machine or plant project is thought through in advance, the less risk there is of having
to carry out expensive modifications during or after commissioning. This applies to both the mechanical and
electrical design. This section can only give a rough overview of electrical design.
11.2

Drive train design

Application, servo drive, motors and gear mechanism must be adapted to each other so that there is an
adequate safety margin for all components as a degree of sluggishness appears over time due to high
temperatures or wear. Make sure that the components in the working area of the system have adequate
reserves so that the working life is not impaired and the necessary control quality can be maintained.
The Beckhoff software "TCMotionDesigner" is available for configuration of the drivetrain and selection of
suitable components.
11.3

Energy management

If the quality of the mains supply is impaired due to wide fluctuations in voltage, then both the servo drive
specification and the speed range of the motor will need to be considered. With a positive tolerance for
voltage fluctuation the upper limit value of the wide voltage input of the AX8000 needs to be taken into
account. With a negative tolerance of the voltage fluctuation it must be checked whether the decrease in
speed caused by the low voltage is permissible. With these motors what is known as field weakening
operation (check availability) of the servo drive may provide a solution. If the mains supply does not meet the
specifications for operation of the AX8000, then isolating transformers, mains chokes, mains filters or other
measures may be required. An energy efficient drive system operates in a drive system with a shared DC
link and shared internal and possibly also external brake resistors. If you are already using similar drive
systems, the AX8000 offers a convenient diagnostic system for determining the load on the brake resistors
and for transferring the values. Previous experience with drive systems shows that in such a system much
smaller or even no external brake resistors need to be used.
The Beckhoff software "TCMotionDesigner" is available for energy management purposes.
11.4

EMC, earthing, screen connection and potential

The AX8000 corresponds to EMC category "C3" (industrial sector) in terms of conducted interference
emissions. If you wish to use components which comply with a higher category you can limit the AX8000
conducted interference emissions with the aid of additional filters to such a degree that this complies with the
EMC category "C2" (residential and industrial environment) or "C1" (residential environments). Ensure that
there is adequate earthing (large-area low-impedance connection) of all relevant components (incl. control
cabinet). The AX8000 incl. periphery, control cabinet, machine bed and motors must be at the same
potential, as the AX8000 control quality will suffer under differing potentials and operational malfunction may
result. Using the screen connection for potential equalisation is not permitted. If you are unable to provide a
uniform reference potential you need to lay potential equalisation cables of adequate dimensions. Smooth
operation is only guaranteed by faultless screen connections of the cables. The screens must be applied
generously at both ends and must on no account be disconnected. Use pre-assembled Beckhoff motor and
feedback cables as these are optimally adapted to the drive system and reduce interference to a minimum.
Ensure that the connectors are properly connected.
AX8000 - system manual
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Project planning
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