Abstract: A method and system is provided for electronically simulating, indicating and controlling the temperature of liquid cooled multi-phase electric power transformers. The temperatures of transformer windings are electronically computed from the actual top oil temperature and the computed incremental additional temperatures resulting from the transformer winding currents to determine the hottest spot temperature. The signals representative of the winding current for each phase of the multi-phase transformer are time processed to simulate the rate of rise of winding temperature resulting from those currents. A square-law function is generated to make a winding bias parameter for each winding. The signals representative of the actual and incremental additional temperature are added for each transformer phase and the largest signal, representative of the hottest winding is used to indicate and control the transformer temperature.

Abstract: A thermometer unit for monitoring the temperature of a fluid cooled electric transformer, the thermometer unit having a ceramic body insertable between the coils of the transformer winding immersed in cooling fluid in the transformer case. A nylon rod responsive to heat changes is confined in the interior of the body and is adapted to expand and contract according to the heat changes to vary volume flow of a gas circulated by a pump in a closed circuit connected with the body. Variations in the gas pressure are indicated on a sight gage externally of the transformer.