As always, you can find out more about AC and DC electrification by downloading my book from https://ocs4rail.com/downloads. Sections 8 and 11 refer.
You can also buy the physical book here: https://www.thepwi.org/product/overhead-line-electrification-for-railways
Finally, you can read my other #RailwaysExplained threads here: https://mas.to/@25kV/110644720069392183
/thread ends