Siemens SIMOTICS S-1FT7 User Manual

Configuration
5.3 Dimensioning the gearbox
S-1FT7 synchronous motors
118 Configuration Manual, 09/2018, A5E45099423B AA
NOTICE
Gearbox failures as a result of superimposed oscillations
Switching cycles can also be superimposed oscillations. The safety factor (f
2
) is then not
adequately dimensioned. This can result in gearbox failures.
• Optimize the overall system so that the superimposed oscillations are minimized.
1
Motor
2
Gearbox
Figure 5-7 Configuring the gearbox
The load torque and required starting speed define the gearbox output torque and the output
speed - and in turn, the output power.
The required drive power is calculated from this:
P
Out
/W = P
Mot
/W ∙ η
G
= ( π/ 30) ∙ M
Mot
/Nm ∙ n
Mot
/rpm ∙ η
G
Dimensioning for S1 duty
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 you must reduce
the torque for S1 duty.
The required motor torque is calculated as follows:
M
Mot
/ Nm
Motor torque
M
V
/ Nm
Theoretical "Torque loss"
a
π/3 for 1FT7/1FK7 motors supplied with sinusoidal current
b
Weighting factor for gearbox losses (without dimensions); b = 0.5
η
G
Gearbox efficiency
i
Gearbox ratio (i > 1)
k
T
/ Nm/A
Torque constant
M
Out
/ Nm
Gearbox output torque
n
Out
/ rpm
Gearbox output speed
n
Mot
/ rpm
Motor speed
R
Phw
/ Ω
Motor phase resistance when warm; R
Phw
= 1.4 • R
Ph
(see Chapter "Technical
data and characteristics")
P
Out
/ W
Gearbox output power
P
Mot
/ W
Motor power
π
pi = 3.1416

Siemens SIMOTICS S-1FT7 Specifications

General

Brand	Siemens
Model	SIMOTICS S-1FT7
Category	Engine
Language	English