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Islanding is undesirable because it may poses safety hazard to utility service personnel and also it can lead to asynchronous reclosure which will damage the equipments. Grid connected PV inverters are required to have passive islanding detection and protection methods that cause the PV inverter to stop supplying power to the utility grid. The active and reactive power equations and Non-Detection Zone of Over/Under Voltage Protection and Over/Under Frequency Protection methods for grid connected PV system under constant power mode inverter are derived and analyzed in this paper. Analyses indicate that the behavior of the PV system at the time of disconnection are depend on the mismatch power, these results also indicate the Non-Detection Zone of Over/Under Voltage Protection and Over/Under Frequency Protection methods are considerable large and include balanced islands which reduces the dependability of these passive methods.