In this paper, a comparative study of the available important passive islanding techniques used for distributed generation is carried out. The following passive methods are compared and analyzed: under/over voltage, under/over frequency, rate of change of frequency, voltage unbalance and total harmonic distortion, rate of change of active and reactive power, rate of change of phase angle difference, and rate of change of negative- and positive-sequence current methods. The above methods are tested and compared for numerous islanding and non-islanding cases by generating data on the IEEE 399-1997 system through PSCAD/EMTDC software.