Servomotor series JHN, JHQ, and JL – User Manual
Introduction
Jetter AG
14
1.7 Definitions of terms and calculation formulas
Definitions of terms
1.7.1
Continuous stall torque
M
o
[Nm]
Thermal limit torque that can be output for any length of time at standstill of the
motor and under rated ambient conditions.
Rated torque M
n
[Nm]
When the motor is drawing its rated current at its rated speed of n
n
, the rated
torque can be delivered for an unlimited period of time in S1 operating mode.
Continuous stall current I
o
[A]
Required rms current for the development of the standstill torque M
o
. The value
refers to the sinusoidal rms current.
Continuous rated current
I
n
[A]
At a rated speed n
n
and at output of the rated torque, the motor will draw the
continuous rated current. This parameter refers to the sine-effective current
value.
Peak current I
max
[A]
Permitted peak current for 5 s max.! The peak current should not exceed 3.5
times the value of the continuous rated current.
Torque constant K
T
[Nm/A]
This constant specifies the amount of torque [Nm] that is output by the motor at
an RMS current of 1 A (M = I * K
T
).
Back EMF constant
K
E
[V/1000 RPM]
This constant specifies the induced electro-magnetic force of the motor related
to 1000 RPM as an RMS value between two motor phases.
Mass moment of inertia
J
M
[kgcm
2
]
The mass moment of inertia is given only for the rotor with standard equipment,
i.e. resolver feedback. Internal or external accessories (holding brake, encoder,
clutch) or a load may affect the values specified in this manual. Therefore, for
calculating the dynamic motor situation the mass moment of inertia has to be
taken into account in its entirety.
Axial load F
A
[N]
Rated axial load of the bare shaft end at the given speed and a ball bearing
service life of 20,000 hours.
Radial load F
R
[N]
Rated radial load of the bare shaft end at the given mean speed and a ball
bearing service life of 20,000 hours. The point where the radial load acts is in
the center of the shaft end.
