Design of a steinmetz symmetrizer and application in unbalanced network

Abstract

The design of delta and star Steinmetz Symmetrizers and applications in unbalanced three phase 4-wire networks supplied from asymmetrical voltages are studied in this paper. Unbalanced current and harmonics shorten motor life spans. An unbalance factor (mi) is defined and harmonics are studied using Superharm (4-wire) models. Two case studies, 1 & 2 are conducted. Case 1 has 1A and 1B and Case 2 has 2A, 2B & 2C. Study 1A is a laboratory set-up used for measurements and in 1B a delta symmetrizer is applied and compared to hand and simulation results. A second network that includes a delta motor and a 4-wire star load (2A) is analyzed (mi, P, Q, PF and IN) and compared to when a star symmetrizer (2B) is applied. The impact of a VSD (2C) on the motor and neutral when the symmetrizer is applied is also analyzed. Findings on Symmetrizers are made.