I want to know the answer to the following question:
What problem arises for fast and large capacity elevators?
All the background I'm provided with is that "The MG set also typically powered the relay controller of the elevator, which has the added advantage of electrically isolating the elevators from the rest of a building's electrical system, thus eliminating the transient power spikes in the building's electrical supply caused by the motors starting and stopping (causing lighting to dim every time the elevators are used for example), as well as interference to other electrical equipment caused by the arcing of the relay contactors in the control system.". Is that enough to answer the question?
Answer: no