Heat dissipation in the rail engines

My question is about the heat dissipation in the rail engines. Engines being a mechanical device gets heatedup on continuous working and heat dissipation must be done and nowadays we are using electric engines, so my point is that how much amount of heat is generated and dissipated from an electric rail engines. Can any one of please help me out in the matter?? And some model calculations related to it would me more useful.