Manual for Induction Motors and Generators
30 -
Installation and Alignment
3BFP 000 050 R0101 REV E
Figure 3-6 Markings on shaft and running center pointer
3.6.4 Correction for thermal expansion
3.6.4.1 General
Running temperatures have a considerable influence on the alignment, and should therefore be
considered during the alignment. The machine temperature is lower during erection than under
operating conditions. For this reason, the shaft center will be higher, i.e. further away from the
feet during operation than standstill.
It may therefore be necessary to use heat compensated alignment depending on the operating
temperature of the driven machine, coupling type, distance between machines, etc.
3.6.4.2 Thermal expansion upwards
The thermal expansion of the distance between the feet and the shaft center of the electrical
machine can be approximately calculated according to the formula:
∆
H =
α
×
∆
T × Hwhere
∆
H=thermal expansion[mm]
α
=10 × 10
-6
K
-1
∆
T=40 K
H=shaft height [mm]
NOTE: Consider the thermal expansion of the driven machine in respect to the electrical
machine in order to define the total thermal expansion.
POINTER
OUTER SEAL
RUNNING CENTER
ROTOR END FLOAT LIMITS
