Patent ID: 8738301

Claim:
In a method of quantitatively analyzing gases for on-load tap changers, the method comprising the following steps: selecting characteristic arc gases including H 2 or C 2 H 2 , thermal gases including CH 4 , C 2 H 6 or C 2 H 4 , and oil-ageing gases including CO or CO 2 produced during the operation of the tap changer and that indirectly allow subsequent association and quantification of ageing effects, excessive discharge, or heating of the tap changer, measuring the concentration of the characteristic arc, thermal, and oil ageing gases in the oil at particular time intervals, forming indicative quotients from the measured concentrations of the characteristic arc, thermal, and oil-ageing gases that allow direct conclusions to be drawn about ageing effects, excessive discharge, or heating, displaying a trend by comparison of the currently derived value of each quotient with one or more of the most recently derived values of the same quotient, and deriving a warning for ageing effects, excessive discharge, and or heating if the corresponding quotients change significantly, the improvement wherein the thermal gases also include C 3 H 8 or C 3 H 6 , the indicative quotient for the occurrence of discharges is the ratio C 2 H 2 /C 2 H 6 ; and the indicative quotient for the occurrence of heating is (C 2 H 4 +C 3 H 6 )/(C 2 H 6 +C 3 H 8 ).