HoST Calculus is the software for thermal design of oil immersed power transformers.

Starting from detailed transformer constructive data, it generates and solves equations corresponding to the detailed hydraulic and thermal networks describing oil flow distribution and heat transfer.

The calculations for the windings are based on two-dimensional networks. The level of details is oil duct or one geometrical turn of the winding.

The software is deeply physically based. It includes equations for the pressure drop and convection heat transfer which are state of the art and the results of own experimental and CFD calculation research.

The software covers comprehensive transformer construction solutions, i.e. takes into account the pressure drop and heat transfer on all elements participating in the oil loops.

One of the outputs of the software is the location of the insulation hot spot, the hot spot temperature and the hot spot factor.

Also, detailed results can be observed in output GUI: o il flow distribution (global, through the cooling system, through the windings, the core and oil by-pass and local - for example inside the winding), oil temperature (global, at the inlet and outlet of the cooling system, the windings, the core and oil by-pass and local - for example inside the winding) and conductor temperature distribution.

There are options to use input GUI, but also to couple HoST calculus with data base via xml files.

The software is a result of the expertise of Professor Radakovic, many years of his devoted and hard work. Also, few brilliant younger engineers contributed the current state of HoST Calculus.