This paper introduces a fault diagnosis of rosin joint in a 110 kV power transformer based on the multi-parameters from dissolved gas analysis

electrical test and operation records.The internal fault diagnosis process is concluded as follows: judging character and development trend of the fault with analysis data of dissolved gas in oil;trying to reduce power load on transformer before power-off in order to control development speed of the fault;narrowing troubleshooting scope through electrical test to locate the fault.The result shows that the multi-parameter comprehensive analysis can effectively judge the characteristic and position of the fault.