Method for measuring degradation level of transformer insulating oil in use, and apparatus for carrying out the method

A method for measuring a degradation level of transformer oil in use, comprising the steps of:

• placing a degradation sensor into a volume of transformer insulating oil for measuring a degradation level of the transformer insulating oil, said degradation sensor including a base ring pierced by a supporting hole in the central part, a porous ceramic material provided with pores and disposed in the supporting hole, and two circular electrodes on both ring sides, the electrodes being held on the base ring by insulating bolts engaging threaded holes in the base ring, the porous ceramic material being adapted to allow impurity conductive particles to pass into the pores, with a lead wire on one of the electrodes being connected to and extending between a terminal on a terminal box of a transformer;
• placing a temperature sensor near the degradation sensor and measuring the temperature of the transformer oil near the degradation sensor, said temperature sensor including a lead wire connected to and extending between a further terminal on the terminal box of the transformer;
• applying a constant DC voltage from a DC high voltage producing unit to the circular electrodes and utilizing a detecting unit for detecting the existence of current conversion values;
• and
• providing circuits which output current signals to the detecting unit of the DC high voltage producing unit, said current signals being amplified and inputted to an A/D converter and thence to a CPU of a microprocessor unit whereat the signals and a current temperature signal from the temperature sensor are compared with existing data stored in the microprocessor unit, stored in the memory of the microprocessor unit, displayed on a display unit and transmitted to a personal computer through a serial port on the microprocessor unit.