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Magtrol TM Series In-Line Torque Transducers
Chapter 2 – Installation / Configuration
Note:
The natural torsional frequency of the drive train is lower due to the
presence of the TM Torque Transducer. The system's own natural
frequency must then be recalculated to determine the influence of
the TM Transducer.
The torsional spring consists only of the deformation zone of the measuring shaft. The torsional
stiffness values (C
t
) are indicated in the technical data sheets (see
Section 1.3
). J
1
and J
2
are the two
moments of inertia acting on each side of the deformation zone. They can be calculated by adding
the moments of inertia of each individual element. The moment of inertia of the measuring shaft is
also indicated in the data sheet. Consult with the suppliers of the couplings, driving element(s) and
driven element(s) in order to obtain the inertia ratings of these drive train components.
The natural torsional frequency (f
0
) determines the following:
• the frequency response of the torque measuring system
• whether or not rapid variations in torque can be accurately sensed
• whether or not the torque signal is amplified or attenuated by the dynamics of the drive
train
The transfer response is plotted in
Figure 2–8
for various quality factor values (q), which are
dependent upon the amount of damping in the torsional system. The graph charts the factor by which
the torque will be amplified, depending on the frequency of the torsional oscillations.
A(f)
A
0
f
f
0
0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0
22
20
18
16
14
12
10
8
6
4
2
0
Q = 30
Q = 10
Q = 3
Q = 1
Figure 2–8 Frequency Response Graph
Note:
The system should be configured and operated in a manner so that
the natural frequency is avoided in everyday operation. The transfer
function should be as close to 1 as possible. Consequentially, the
frequency of the drive train torsional oscillations should be less
than ~0.5 f
0
.
