  We review in a systematic way how anomaly free $SU(3)_c\otimes SU(3)_L\otimes
U(1)_x$ models without exotic electric charges can be constructed, using as
basis closed sets of fermions which includes each one the particles and
antiparticles of all the electrically charged fields. Our analysis reproduce
not only the known models in the literature, but also shows the existence of
several more independent models for one and three families not considered so
far. A phenomenological analysis of the new models is done, where the lowest
limits at a 95\% CL on the gauge boson masses are presented.
