Conclusions about the study of the special connections at the three-phase transformers

This paper presents the conclusions about the study of the special connections at the three-phase transformers, ie: fan connection, which is obtained from star connection through a phase inversion, which results in an asymmetric system voltages; the V connection, which can be obtained from the delta connection, through the suppression an phase - V_D and from the star connection, through the suppression an phase - V_y, connections that have been studied and used in the Research Center for Devices Machines and Drives at the University “Stefan cel Mare”, by realization and experimentation of a phase sequence indicator, which is used mainly to check the phases sequence of the three-phase power supply, for load switches, used for control voltage regulation in power transformers; and star connection with unequal arms, (the ψ scheme) which was created to enable to power supply from the same source, both at the single-phase portable power tools, and also at the three-phase portable power tools.