Lenze DSD - Manual (Page 396)

15 Results: comparing, optimising, logging
15.6 Reserves with regard to the drive dimensioning
396
Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
15.6 Reserves with regard to the drive dimensioning
In order to avoid a multiple consideration of reserves, no reserves whatsoever are allowed for in the
DSD (exception: DC bus power in the multi-axis grouping).
• The DSD supports the decision-making with regard to the reserves by displaying all utilisation
degrees. However, you have to decide for yourself whether a smaller component (inverter, mo-
tor, or gearbox) still suffices.
• In order to avoid a selection of reserves that are too big, it usually is assumed that the system
planner has also already provided for reserves without explicitly mentioning this.
15.6.1 Dynamic reserves
These are reserves of the inverter-motor combination with regard to the torque.
• The dynamic reserves should at least be 15 ... 25 %, so that the drive can always be controlled in
a safe manner.
15.6.2 Stationary reserves
These are reserves for the rated point of the drive component, i. e. usually thermal reserves.
• The stationary reserves can turn out slightly smaller than the dynamic reserves. There are appli-
cations which can be operated with a thermal reserve of the motor of 0 %.
• Recommended values: 5 ... 15 %, depending on the application and safety relevance.

Note!
Generally, sufficient reserves are to be provided for with regard to drive dimensionings,
so that:
• the application is always under control (inverter may not run in current limitation),
and the drive does not become uncontrollable if there are slight changes with regard
to the load or to sluggishness.
• the drive is not operated above its rated data thermally and with regard to its service
life (this particularly applies to gearboxes).
Of course, on the other hand, the reserves should not be too big, because after all this is
a competitive factor possibly resulting in unacceptable price/performance ratios.
With regard to the amount of the reserves, note the comments in the following
subchapters!