Siemens SIMODRIVE 611A Installation And Planning Manual page 210

2.2 Mounted/integrated components
General information on AC servomotors
AL S
AL S/2-12
2. Selecting the motor size
The load torque and the required traversing velocity define the gearbox
drive–out torque and the drive speed and therefore also the drive output.
The required drive output can then be calculated from this data:
η
P [W] = P = (π/30) M
from mot
G
The gearbox prevents heat from being dissipated through the motor flange,
and the gearbox itself generates friction heat.
The torque must be reduced for S1 duty.
Dimensioning for S1 duty
The required motor torque is calculated as follows:
M
out
M =
( + M
mot
i *
G
n
mot
with MV = a * b *
60
M calculated "torque loss"
V
π/2 for 1FT5 motors fed with squarewave current 1FT5
a
π/3 for 1FT6 motors fed with sinusoidal current
b 0.5 weighting factor for gearbox losses
(no dimensions)
n Motor speed [RPM]
mot
K Torque constant [
T
R Thermal resistance of the motor phase [Ω] = 1.4 R
ph.
M Gearbox drive–out torque [Nm]
out
i Gearbox ratio (i>1)
η
Gearbox efficiency
G
P Motor output [W]
mot
P Gearbox drive–out power [W]
out
M Motor torque [Nm]
mot
Typical efficiency:
Planetary gearbox
Spur gearing
Cyclo gearbox
Harmonic drive
Worm gear
Dimensioning for S3 duty
The torque does not have to be reduced.
/ (i η
M = M
mot red
G
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[RPM] η
[Nm] n
mot mot
2 2
) – M
V V
2
K
T
(1 –
) *
G
R
ph.
Nm
]
A
η 0.94
Single–stage
η 0.95
η 0.92
Single–stage
η 0.7
η 0.45...0.9
)
08.95
G
(list)
ph.
6SN1197–0AA20
SIMODRIVE 611 (PJ)