
Noise and Vibrations of Electrical Rotating Machines 9-11
9.4.1 Amplitudes of Static Distortions
9.4.1.1 Static Distortions
For given
f
mM
, the relationships that dene Y
ms
depend on the m values. ey are given by (9.10), (9.11),
and (9.12), respectively for m = 0, 1, and m ≥ 2. e following notations are used (Figure 9.13):
• R, internal radius of the stator
• R
y
, yoke average radius
• T
y
, yoke radial thickness
• L, iron length
• L
s
, distance between rotor sha supports
• d, sha diameter
• E, elasticity coecient or Young’s modulus: E = 2.1 × 10
11
N/m
2
for iron
Y
RR f
ET
s
y mM
y
0
=
ˆ
(9.10)
Y
RL L
f
Ed
s
s
mM
1
=
4
3
3
4
ˆ
(9.11)
Y
RR f
ET m
ms
y mM
y
=
−
12
1
3
3 2