Elektrical power sistem protection in substation is use to protect the power system equipment from over voltage due to lightning strike. Arrester are a device use to protect elektric power sistem equipment in substation from lightning strakes and short circuit. The purpose of this reaserch is to obtain the ideal distance in teh placement of arrester and trasformator for lightning sreakes using ATP (Alterntive Transient Program) software simulation at the substation 150 kV Kentungan. The method used is by determine the placement of the arrester to the transtormator using ATP software simulation and to the comparison with the calculation Alterntive of a arrester placement based on standari of IEC 1958 and SPLN 1978. The result of the comparison of the overvoltages value in the pimery side trasformator as the current of lightning srakes 10 kA is 3,79 MV, the current of lightning srakes 20 kA is 7,38 MV and as the current of lightning srakes 40 kA is 13,93 MV for the unistalled system of arrester. 164,68 kV for the installed system of the arrester with the distance of 5 meters and 312,93 kV for the installed system of the arrester with the distance of 28,5 meters as a current of lightning arrester 10 kA, 244,17 kV for the installed system of the arrester with the distance of 5 meters and 357,39 kV for the installed system of the arrester with the distance of 28,5 meters as a current of lightning arrester20 kA and 268,70 kV for the installed system of the arrester with the distance of 5 meters and 414,22 kV for the installed system of the arrester with the distance of 28,5 meters as a current of lightning arrester 10 kA. The voltages value of lightning stikes when the duration time of stike is a 5E-5 and the duration time of wave 1,2E-6 is greater than the value of the lightning strike voltage at the the duration time of stike is a 11E-5 and the duration time of wave 2,4E-6. Because the smaller time of duration strak and duration wave of the lightning strike then the time required to reach the peak voltage faster.