Abstract
The hot-spot factor (H) is a crucial component of the thermal diagram in IEC 60076-2 to derive the hot-spot temperature from the test data. In this paper, H is expressed as the sum of two separable components, one relating to convection in the fluid domain and the other relating to conduction in the solid domain. Dimensional analyses on fluid flow and heat transfer show that both components are functions of dimensionless winding geometry, loss distribution, Re and Pr. The relationship between H and Re and Pr for a fixed winding geometry with uniform loss distribution is obtained by conducting computational fluid dynamics (CFD) parametric sweeps and multilayer least-square based correlation. The correlation obtained is verified by the consistency between H from new CFD simulations and those from the correlation. For nonuniform loss distribution, H is a function of Re, Pr and the Q factor. When the hot-spot is at the location of the highest power loss, H is in a linear relationship with Q and this linear relationship is coupled with a nonlinear relationship between H and Re and Pr.
| Original language | English |
|---|---|
| Journal | IEEE Transactions on Power Delivery |
| Volume | PP |
| Issue number | 99 |
| DOIs | |
| Publication status | Published - 29 Jun 2017 |
Keywords
- CFD
- Dimensional analysis
- disc winding
- fluid flow
- Fluids
- Heat transfer
- heat transfer
- hot-spot factor
- OD cooling mode
- Oils
- Temperature distribution
- Temperature measurement
- Temperature sensors
- transformer
- Windings