These methods have two problems. One with both discrete of them is miscoordination and the other is not having the solution for relays and continuous time setting multipliers (TSMs). In [7] the mentioned problems have been solved. In the cases that the distance relay is considered to be main and the over current one is the backup relay, it is necessary to find the critical fault locations. The critical fault locations are the locations at which, the discrimination time (Δt) between the backup and main relays is at its minimum. The coordination is made based on the constraints derived from the values of Δt for critical fault locations.