This thesis concerns design, manufacturing, modelling and test of a water cooling system for a transformer. The cooling system is invented by Johnson Controls, and is intended to be implemented in a permanent magnet synchronous motor (PMSM), used to drive an axial compressor for a water vapour chiller. The cooling system is named "Enhanced Core Cooling".
The cooling system appears to be highly effective, thereby permitting higher power densities in electrical machines.

A well-functioning waterproof prototype of the transformer is build, and several DC and AC test are performed to clarify the cooling systems ability to handle copper and iron losses.

The temperature distribution in the transformer is modelled by four different models: an analytic model, a lumped parameter model, a FEM analysis and a CFD analysis. The analytic model show the right tendencies but are too simplified to be accurate compared to the temperature measurement. The lumped parameter model and the FEM analysis are generally consistent with the temperature measurement, and may be used as simple and effective design tools the further development of the Enhanced Core cooling system in electrical machines.
The CFD model behaves non conservative as the heat transfer for forced water convection is overestimated.

It is finally discussed how the Enhanced Core Cooling can be implemented in a PMSM. It is estimated that the Enhanced Core Cooling can sink up to 6 kW from the PMSM. With an estimated loss of 1 kW, the Enhanced Core Cooling is concluded to be an effective solution to cool the PMSM.