The discharge characteristics of typical partial discharge source are analyzed for commercial switchgear.Transient Earth Voltage（TEV）and ultra-high frequency（UHF）detection technology are used to detect and analysison the typical partial discharge source. Experimental results show that as the applied voltage increases

partial dis-charge quantity increases gradually

and the phase of discharge becomes wider. An approximate linear formulationcan be used to describe the relationship between the relative amplitude and the applied voltages

the relative ampli-tude can show the severity of partial discharge. Partial discharge signals with different typical defects are different indischarge pulse phase spectrum. When two typical defects coexist the Phase Resolved Partial Discharge（PRPD）aresuperimposed

and the PRPD shape will be complicated

it can be distinguished according to the typical map of typical partial discharge.