Abstract: This paper simulated a generator circuit breaker model using ATP-EMTP simulation package. The frequency of oscillations produced at current zero is reduced as the short circuit current increased. At 80 kA short circuit a resignation is happened at first current zero, while the success interruption is happened at the second current zero, at a capacitance of 8.3nF. As the short circuit current increases, more than 80 kA, the circuit breaker fails to interrupt with the small terminal capacitor, i.e. 8.3nF, 10nF and 20nF. The TRV is decreased as the value of the terminal capacitor increased. At a certain value of the terminal capacitor, the TRV is increased with increasing the short circuit current. The RRRV decreases as the value of the terminal capacitor increased. Also, at a certain value of the terminal capacitance, the RRRV decreases with decreasing the short circuit current.