Which of the following statements about the nature of speed control required by different industrial drives is INCORRECT?
1
Some drives require only one fixed speed over a region; such drives are called mono-speed drives.
2
Some drives require continuously variable speed over the range from zero to full speed; such drives are called variable speed drives.
3
Some drives require only two or three fixed speeds over a region; such drives are called multi-speed drives.
4
In some cases, speed is needed for adjusting the work on a driven machine only for a few revolutions per minute; such a speed is known as creeping speed.