Appendix
A.1 Description of terms
1FT7 Synchronous Motors
244 Configuration Manual, (PFT7S) 01/2009, 6SN1197-0AD13-0BP2
Rated current I
N
RMS motor phase current for generating the particular rated torque. Specification of the
RMS value of a sinusoidal current.
Rated speed n
N
The characteristic speed range for the motor is defined in the speed-torque diagram by the
rated speed.
Rated torque M
N
Thermally permissible continuous torque in S1 duty at the rated motor speed.
Shaft torsional stiffness c
T
This specifies the shaft torsional stiffness from the center of the rotor laminated core to the
center of the shaft end.
Stall current I
0
Motor phase current for generating the particular static torque. Specification of the RMS
value of a sinusoidal current.
Static torque M
0
Thermal limit torque at motor standstill corresponding to a utilization according to 100 K or
60 K. This can be output for an unlimited time when n = 0. M
0
is always greater than the
rated torque M
N
.
Thermal time constant T
th
Defines the increase in the motor frame temperature when the motor load is suddenly
increased (step function) to the permissible S1 torque. The motor has reached 63% of its
final temperature after T
th
.
Torque constant k
T
(value for a 100 K average winding temperature rise)
Quotient obtained from the static torque and stall current.
Calculation: k
T
= M
0, 100 K
/ I
0, 100 K
The constant applies up to approx. 2 ∙ M
0, 60 K
in the case of self-
cooled motors
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