A 500MVA transformer is delivering full-load at a power factor of 0.8 lagging. At this load point the transformer is 98.5% efficient. The transformer can be modelled in thermal steady-state by a “hot-spot”, or worst case thermal resistance to ambient of Rth = 1x10-5 [K/W]. Assume the ambient temperature, Ta = 25oC, calculate the hot-spot temperature for this load condition.
