Calculation of temperature in directly cooled electrical machines

There has been a big effort over a number of years to provide the analysis tools to allow an accurate assessment of the temperature rise in turbogenerator stator cores. The method adopted by the author uses an equivalent network model. The circuit equations contain highly nonlinear fluid resistances and fan characteristics and the various constants and indices required are highly empirical. It is the case however that long experience of similar topologies coupled with extensive rig work has allowed a measure of reliability to be ensured in the fluid flow solution. Given the flows and using further empirically based equations it is possible to derive heat transfer coefficients to describe the temperature drop between the bulk fluid and the surface of the conducting body