BECKHOFF Drive Technology 7 Project planning – important information
AX5000 Version 6.2 47
7 Project planning – 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.
7.1 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.
7.1.1 Control quality, mass inertia ratio and load connection
Control quality is dependent on the parameters "mass inertia ratio" and "load connection":
Control quality / Dynamics
The "Control quality / dynamics" is primarily affected by the mass moment of inertia: a poor
"Control quality / dynamic" due to an unfavourable mass moment of inertia cannot be
improved even with a very good load connection. Likewise, however, a good "Control quality
/ dynamic" due to a favourable mass moment of inertia can be reduced through a poor load
connection.
7.2 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 AX5000 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 AX5000, 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 or brake modules. If you are already using similar drive systems, the AX5000 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 / brake modules need to be used.
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