Since the procedure of preventive test for bushings is complex and easily interfered by the grounding net

it is difficult to find out earlier defects effectively. Some scholars put forward a novel PD location method for bushings based on TDOA of UHF signals. It is vital that it must access the TDOA automatically and accurately regardless of the features of different signals. This paper makes investigation on measurement of TDOA of UHF signals radiated by different partial discharges occurred in bushings. Firstly

the classical method in time domain are introduced;Secondly

methods of TDOA according to the features of UHF signals propagated through various paths are raised;Finally

the accuracy of measurement is proved by the experiment results. Test results show that:1)for the signals propagated through unitary path which have higher correlation degree

the correlation method has high stability and good accuracy;2)for the signals propagated through a complex path which show longer duration

especially PDs in the oil barrel

the minimum energy method is more stable and accurate. The research is valuable and meaningful to PD location for bushings.