Exactly, some of us in this thread have very good (professional) understanding of traction electric system performance and efficiency and some others just don't!!! The person you are reply to has a massive misunderstanding of some or all of data, maths and/or engineering English.
In many recent traction systems there has been a trend to high voltages for IGBT which has also reduced the apparent SiC advantage has that often had a higher motor voltage assumption included hence they often weren't often apple vs apples comparisons.
350s have 20.Xm vehicles and 730s have 24.Xm vehicles hence a 10car 730 is equivalent to a 12car 350; however the 350s are known for being heavy so a 12 car Cl350 tare is 538 tonnes, 8car 359 tonnes and a 10car 730 is 396 tonnes. The main differences in 12car 350 vs 10 730 has come from mass reduction (142 tonnes) : lighter body shells despite being 4m longer, 4 fewer bogies, 2 fewer cabs, 20 inside frame bogies compared to outside frame and better electrical system design and integration also saving some weight, totalling 142 tonnes. Yes the electrical system is better but saving 26.3% on weight is a huge factor. Better HVAC and auxiliary efficiency has also helped
I cannot claim myself an expert on this matter. In fact, what bother me the most is the lack of information.
The comparison between 350s and 730s you post, such as reduction in weight while maintaining the same capacity, and improvement to other electrical equipment, are excellent context. I highly appreciate this as electricity saving can then be estimated.
I think, there should be case studies on electricity consumption upon new rolling stock introduction. National Rail is running tight on electricity supply all the place. Introducing more electricity efficient EMUs and actively talk about it is an important advertisement for the railway, not only justifying the update, but also promoting future investment.
In fact, analyses are done extensively outside National Rail. The comparison between Chopper, GTO, IGBT and SiC stock are from Japan Railway (mostly JR East). There is also comparison on energy consumption for China high speed trains [1] and the paper was published to Journal of Advanced Transportation, a British publication. Even for London, TfL/Siemens estimated the 2024 stock will have 20% energy efficiency improvement (after adding HVAC) over the stock it is replacing before it is introduced. Unlike UK, electricity supply isn't a bottleneck for both China and Japan. Saving electricity is very much icing on the cake for them. Yet, this matter the most for National Rail but was talked the least.
[1]
https://www.proquest.com/docview/2667632536
Also, improved efficiency is a term used to describe the amount of energy lost in the conversion (DC to AC or AC to AC) and not the total amount of energy used. Thus a SiC converter might be 10% more efficient than an IGBT model. Based on the IGBT system being at least 90% efficient, if the SiC system is 10% more efficient than the IGBT, this means that it'll be 92% efficient in converting the energcy from one form to the other.
Is incorrect in the assertion about enabling capacity for an 11th train. Equally an energy consumption comparison between the 8-car class 350 and the 10 car class 730 depends on many more factors than the traction converter technology. The biggest difference will be in train mass and performance specified.
SiC inverter also brings improvement to the weight and size, as well as specific usage such as regenerative braking.
The 10%-20% figure JR East claimed for the E235 account for new inverter-traction system, in car energy management (e.g. LED lighting and enhanced HVAC) and optimised traction profiling through ATO (automatic train operation)
