This paper provides a description of a new approach for steady state securi
ty evaluation, using fuzzy nearest prototype classifiers, The basic method
has an off-line training phase, used to design the fast classifiers for on-
line purposes, allowing more than the two traditional security classes. A b
attery of these fuzzy classifiers, valid for a specific configuration of th
e network, is adopted to produce a global evaluation for all relevant singl
e Contingencies. An important feature of this approach is that it selects a
utomatically the most appropriate number of security clusters for each sele
cted contingency. Natural language-labeling is also used to produce standar
dized sentences about the security level of the system, improving in this w
ay the communication process between the system and the operator. The paper
is completed by an example on a realistic model of the Hellenic interconne
cted power system, where seven contingencies were simulated.