Aiming at the repeated tripping accidents caused by buchholz relay protection actions

the history of repeatedly tripping accidents of the main transformer in a 35 kV substation over the past few years is analyzed

and it is found out that the through current generated by the fault outside the main transformer area may be the important cause of main transformer tripping. A large number of electrical power protection tests and non-electrical power protection tests are carried out on the main protection device of transformer by setting up a test platform. The reasons why the heavy gas protection action of main transformer tripped but there is no action message are found out

and it is proposed that the setting value of heavy gas protection is set as the highest upper limit within the standard range to prevent the through current generated by the fault outside the main transformer area from causing the malfunction of heavy gas protection.