A new phase selector based on zero sequence and the sum of positive sequence and negative sequence is put forward. According to the relative relation of zero sequence with the sum of positive sequence and negative sequence， it selects the grounded fault phase combined with the phase selector using zero sequence and negative sequence. The phase selector has overcome the disadvantage of previous phase selectors influenced by the transition resistance， and the principle of the fault selector is simple. Principle analysis and examination of lots of digital recorder data show that it can correctly select the fault phase and is an ideal phase selector to achieve automatic re-closure in electric power transmission line protection.