Siemens 1FT7 - Page 242

Appendix
A.1 Description of terms
1FT7 Synchronous Motors
242 Configuration Manual, (PFT7S) 01/2009, 6SN1197-0AD13-0BP2
Maximum permissible speed (mechanical) n
max
.
The maximum mechanically permissible speed is n
max mech
. It is defined by the centrifugal
forces and frictional forces in the bearing.
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).
Maximum speed n
max
The maximum mechanically permissible operating speed n
max
is the lesser of the maximum
mechanically permissible speed and the maximum permissible speed at the converter.
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
ph
∙ J
mot
/k
T
2
[s]
J
mot
= Servomotor moment of inertia [kgm
2
]
R
ph.
= Phase resistance of the stator winding [Ohm]
k
T
= Torque constant [Nm/A]
Maximum torque M
max
Torque that is generated at the maximum permissible current. The maximum torque is briefly
available for high-speed operations (dynamic response to quickly changing loads).
The maximum torque is limited by the closed-loop control parameters. If the current is
increased, then the rotor will be de-magnetized.
Maximum torque (limited by converter) M
max conv
The maximum torque that can be applied (temporarily) for operation on the recommended
motor module.
NDE
Non-drive end = Non-drive end of the motor
Number of poles 2p
Number of magnetic north and south poles on the rotor. p is the number of pole pairs.