Lenze DSD - Manual (Page 114)

7 Applications
7.8 Hoist drive without counterweight
114
Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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7.8.1 Calculations
For a hoist without counterweight according to the drawing the following applies:
When a cable drum is wound up and unwound, the effective radius changes, which is required for
the calculation of the torque acting on the cable drum. Since, depending on the operating mode
(constant speed or constant lifting speed), the speed or velocity changes, the dimensioning process
is carried out according to the base process power, and the most unfavourable case is assumed:
[7-75] Equation 1: Base process power
[7-76] Operating modes
1. Operating mode with a constant speed
• In the case of this operating mode which is the most frequently used, the input speed – irre-
spective of the respective layer – is kept constant on the winding drum.
• During a layer change, the lifting speed increases abruptly with every additional layer.
• The torque required changes abruptly during a layer change (layer 1, 2, … n).
2. Operating mode with a constant lifting speed
• In this operating mode, the input speed is altered depending on the current layer on the cable
drum, so that always a constant lifting speed (v = d
Cor
* n * π/60) is reached. For this, the in-
verter or an external control has to update the speed depending on the layer.
• The required torque also changes abruptly during a layer change. The difference with regard
to the operating mode with a constant speed is that the highest speed and the highest torque
do not occur simultaneously.
The DSD carries out the dimensioning process identically for both operating modes according to the
base process power (product from max. torque and max. speed). During all calculation routines and
graphic representations only the maximum values are ascertained and displayed.
P
cto
M
sds,max
n
max
2 π ⋅
60
----------- ⋅ ⋅ =
 Operating mode with a constant speed
 Operating mode with a constant lifting speed
n
Œ 
M
M
0,max
n
max
Layer 5 (d )
max
Layer 4
Layer 3
Layer 2
Layer 1 (d
)
min