Electrical power system protection is used to protect the power system equipment from over voltage due to lightning strike. Lightning arrester or commonly known as arrester are a device used to protect electric power system equipment from abnormal conditions due to lightning strikes (surge impulse) and short circuit (switching). The purpose of this reaserch is to obtain the ideal distance in the placement of arrester and power transformer against over voltage protection using ATP (Analysis Transient Programme) simulation software in Bantul Substation 150 kV. The method used is by determine the placement of the arrester to the transformer using ATP Draw software simulation and to do comparison with the calculation analysis of arresters placement based on the standard of IEC (1958) and SPLN (1978:4). The comparison of the overvoltage value in the primary side transformer while the lightning advance time of 1.2454 x 10-3 ms is 861.06 kV for the uninstalled system of arrester, 215.43 kV for the installed system of arrester with a distance of 3.15 meters from the transformer and 215.48 kV for the system installed arrester with distance of 15 meters from transformer. The value of the lightning strike voltage at 0.012401 ms is greater than the value of the lightning strike voltage at 0.03410 ms. This is because the smaller the face time of the lightning strike then the time required to reach the peak voltage faster.