Thyristor traction rectifiers engineering and hype

When the American transit industry discovered "thyristor rectifiers" (typically known as controlled rectifiers or SCR rectifiers), at least in the press, traction power engineering changed completely. Claims of fewer energy costs, lower capital costs increased spacing, lower maintenance costs, and even elimination of the need for DC circuit breakers ushered in this "discovery". The facts are the cost is higher, the maintenance is higher, the spacing is primarily driven by other factors, there are many reasons that DC breakers are necessary, and controllable rectifiers introduce a host of problems which have had to be addressed (usually successfully) in industry. One transit authority in the United States made the decision to build a system based on controllable rectifiers. Some of the claims and compromises involved in that system are used in evaluating the thyristor rectifiers in regulation, energy savings, and regeneration.