Correction For Thermal Expansion; General; Thermal Expansion Upwards - ABB AMA Series Manual

Manual for Induction Motors and Generators
RUNNING CENTER

3.6.4 Correction for thermal expansion

3.6.4.1 General

3.6.4.2 Thermal expansion upwards

30 - Installation and Alignment
POINTER
OUTER SEAL
Figure 3-6 Markings on shaft and running center pointer
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.
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 -1
K
∆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.
ROTOR END FLOAT LIMITS
3BFP 000 050 R0101 REV E