Abstract: Abstract:The automatic bus transfer equipment for 110kV input line is almost used in terminal load substations. The bus differential protection is not configured in these substations. The bus faults are permanent faults commonly. Under this condition, the automatic bus transfer equipment did not be locked out and acted to switch the standby power on the failed bus, which caused impact on the transformer repeatedly. Taking the automatic bus transfer equipment for single bus segmentation input line as example, it was proposed to investigate the input side line current and to judge the bus fault according to the variation of the input line current, and the judge result can be used as decision condition to lock out the automatic bus transfer equipment.

Key words: Keywords:input line, automatic bus transfer equipment, bus fault, input line current, lockout of automatic bus transfer equipment