Abstract

A method and system for indicating and controlling the temperature of liquid cooled multi-phase power transformers. The winding temperatures of a transformer are electronically computed from the actual top oil temperature and the incremental additional temperatures resulting from the highest transformer load current to determine the hottest spot temperature. One curve from a family of curves representing the incremental temperature for various transformers may be selected or programmed by adjustments made which simulate the incremental additional temperature which results from transformer winding current. In this way the input current range, winding bias setpoint, winding bias curve, and time-constant can be chosen independently so that any electric power transformer may be simulated. The total temperature value resulting from the addition of both the top oil temperature and the highest load current induced incremental temperature are used to control indicators, cooling fans, circuit trips and retain an indication of the hottest spot temperature reached during the time period of interest.