<human>: Q: What problem arises for fast and large capacity elevators?
 A: Historically, AC motors were used for single or double speed elevator machines on the grounds of cost and lower usage applications where car speed and passenger comfort were less of an issue, but for higher speed, larger capacity elevators, the need for infinitely variable speed control over the traction machine becomes an issue.
 Does the answer correctly answer the question

OPTIONS:
- yes
- no
<bot>: yes