The Electroacoustic Pulse (PEA) method used in the space charge measurement of AC electric field in existing research has low phase resolution. The measured space charge is mainly the interface charge of the peak phase at the electrode. In this paper, the distribution of space charges in cross-linked polyethylene(XLPE) and the threshold electric field for bulk charge accumulation at different frequencies are investigated. The space charge test adopts the PEA test method improved by automatic equalization phase shift(AEPS) to achieve a high phase resolution of 1.8°. Three typical frequency points of high-frequency 10kHz, power frequency 50Hz, and low-frequency 0.01Hz were selected. Heteropolar charges are accumulated at the interface of XLPE samples in the range of 1~50kV/mm at different frequencies; During the complete AC cycle, the amount of charge accumulated inside the AC field at different frequencies is Q_0.01Hz>Q_50Hz>Q_10kHz. The heteropolar charge at the interface mainly comes from the dissociation of internal impurities, which reduces the charge injection barrier and promotes the charge injection under the AC electric field; The threshold electric field of XLPE in the sinusoidal frequency range of 10kHz~0.01Hz has no obvious change with frequency.
 

polyethylene material,sinusoidal electric field,space charge,threshold electric field