Oil / Winding Temperature Indicator

Winding Temperature Indicator : The Winding is the component with highest temperature within the transformer and, above all, the one subject to the fastest temperature increase as the load increases. Thus to have total control of the temperature parameter within transformer, the temperature of the winding as well as top oil, must be measured. An indirect system is used to measure winding temperature, since it is dangerous to place a sensor close to winding due to the high voltage. The indirect measurement is done by means of a Built-in Thermal Image.

Winding Temperature Indicator is equipped with a specially designed Heater which is placed around the operating bellows through which passes a current proportional to the current passing through the transformer winding subject to a given load. Winding Temperature is measured by connecting the CT Secondary of the Transformer through a shunt resistor inside the Winding Temperature Indicator to the Heater Coil around the operating Bellows. It is possible to adjust gradient by means of Shunt Resistor.

In this way the value of the winding temperature indicated by the instrument will be equal to the one planned by the transformer manufacturer for a given transformer load.