Siemens SIMOTICS S-1FT7 - Page 403

Appendix
A.1 Glossary
S-1FT7 synchronous motors
Configuration Manual, 09/2018, A5E45099423B AA
401
Maximum permissible speed at converter n
max conv
The maximum permissible operating speed for operation at a converter is n
max conv
(e.g.
limited by withstand voltage, maximum frequency).
Mechanical time constant T
mech
The mechanical time constant is obtained from the tangent at a theoretical ramp-up function
through the origin.
T
mech
= 3 ∙ R
Str
∙ J
Mot
/ k
T
2
, T
mech
/ s
J
mot
=
Moment of inertia of the servomotor / kgm
2
R
Str
=
Resistance of one phase of the stator winding / ohm
k
T
=
Torque constant / Nm/A
NDE
Non-drive end of the motor
Optimum operating point
Operating point at which the maximum continuous output of the motor is normally provided
at high efficiency (see figure below).
A
Torque
1
Optimum operating point
B
Efficiency
2
Optimum speed
C
Output power
3
Optimum power