atmasphere-
Your point about non-sinusoid output waveform and generated secondary harmonics are well taken.
However, Sola mitigated this by adding an additional “neutralizer” winding in the secondary. The following document contains a description of how it works. Refer to the PDF page 4 under the heading “Ferroresonant power conditioners and harmonics”.
https://www.emerson.com/documents/automation/product-guide-solahd-power-conditioners-en-us-99748.pdf
Your point about non-sinusoid output waveform and generated secondary harmonics are well taken.
However, Sola mitigated this by adding an additional “neutralizer” winding in the secondary. The following document contains a description of how it works. Refer to the PDF page 4 under the heading “Ferroresonant power conditioners and harmonics”.
https://www.emerson.com/documents/automation/product-guide-solahd-power-conditioners-en-us-99748.pdf