1. A training simulator for training an operator in the operation of an electric power system comprising: trainer input-output means having a plurality of pushbuttons respectively corresponding to a plurality of training items regarding training simulation for manually selecting one of said items to be subsequently executed; trainee input-output means to enter proper data in response to simulated conditions provided through the execution of the selected training item; and a first central processing unit connected to said trainer input-output means; a second central processing unit connected to said trainee input-output means; a third central processing unit for simulating various modes of operation of the electric power system; a first external memory accessible by each of said central processing units; a second external memory accessible by said second central processing unit; said central processing units providing means for executing a training review from the beginning of the training when a first command to restart the training is issued from the trainer input-output means and for executing another training item in response to a second command issued from the trainer input-output means designating conversion from the training review into another training item, during the execution of the training review.