The two abnormal temperature rising of connection fittings in UHVDC ±800 kV Fufeng line are monitored and tracked

and base on infrared thermometry and software simulation

the simulation analysis show that the cause of the abnormal temperature rising of No.1564 and No.1250 is the current in the bundled conductors are unbalanced

the current in the bundled conductors need balanced by the connection fittings before re-transmission

the large current in the connection fittings of No.5 bundled conductor caused the abnormal temperature rising. The maintenance results show that the joint of the No.5 bundled conductor and the tubular busbar is loose contacted to No.1564 and No.1250

the maintenance results meet the reason analysis of the authors. The suggestion of carefully reviewed on the joint of the bundled conductors and the tubular busbar is proposed. And to this abnormal temperature rising problem

if the safety factor of the connection fittings is within safe levels

the defect could keep operation until the next maintenance time.