SCOTT TRANSFORMER –ANALISYS, DESIGN AND EXPERIMENTATION

Abstract

The following paper reports methods of analysis
and development for Scott connection, which comprises two
single-phase transformers connected so that phase
conversions are possible. The possibilities of three-phase-totwo-
phase conversion and vice-versa (Reversibility
Principle) are proved using vectorial analysis, digital
simulations and experimental results. No load and full load
tests were carried out with a 500 VA prototype to examine
the main waveforms, windings’ turn ratios and efficiency
curve. Effects of harmonic distortion from power supply on
the voltage shapes, are commented. Considering 90º shifting
between voltages in the two-phase side, a split phase
induction motor was driven without starting capacitors. This
feature shows that the Scott connection can be used to
provide initial torque, increasing machine’s performance
since the reverse magnetic field of the motor is completely
eliminated during all operation range.

Index Terms ⎯ split phase induction motor, three-phase to two-phase conversion, Scott connection, transformer.