Siemens MASTERDRIVES MC 1FK7 - Dimensioning for S1 Duty for Naturally Cooled Systems

Gearboxes
Selecting/dimensioning gearboxes and important parameters/quantities
1FK7 Synchronous Motors
5-2 Configuration Manual (PFK7), 10/2005 Edition, 6SN1197-0AD06-0BP1
Fig. 5-1 Dimensioning the gearbox
The load torque and the required traversing velocity define the gearbox output torque, the
output speed and therefore the output power.
The required drive power is calculated from this:
P
out
[W] = P
mot
• η
G
= (π/30) • M
mot
[Nm] • n
mot
[rpm] • η
G
5.1.3 Dimensioning for S1 duty for naturally cooled systems
The gearbox itself generates heat due to friction and acts as a thermal barrier preventing heat
from being dissipated through the motor flange. This is the reason that the torque must be
reduced for S1 duty.
The required motor torque is calculated as follows:
Notice
Switching cycles can also be superimposed vibration! The supplementary factor (f2) is then
not sufficient when dimensioning the gearbox and gearboxes may fail.
The complete system should be optimized so that the higher-level vibration is minimized.
6\QFKURQRXV
PRWRU
*HDUER[
Q
PRW
Q
$
L 
Q
PRW
Q
$
M
V
Calculated "torque loss"
a π/2 for 1FT5 motors fed with square-wave current
π/3 for 1FT6/1FK motors supplied with sinusoidal current
b 0.5 weighting factor for gearbox losses
(without dimensions)
n
mot
Motor speed [rpm]
k
T
Torque constant [Nm/A]
R
ph.
Motor phase resistance when warm
[Ω] = 1.4 R
ph.
(Catalog)
M
out
Gearbox output torque [Nm]
i Gearbox ratio (i>1)
η
G
Gearbox efficiency
P
mot
Motor power [W]
P
out
Gearbox output power [W]
M
mot
Motor torque [Nm]
SK
PRW
9
*
RXW
PRW
ZLWK
99
( )
2
7
*
2 2
•
1
6 0
• b • a = ) +
• i
( =
R
k n
M M M
M
M -
-