Description : Why do we close the switch at 11 o'clock and not at 12 o' clock?
Last Answer : When the synchroscope is approaching 12 o'clock the "slip" (differential) between the sine waves is approaching minimum (slip is zero when the synch'scope is at 12 o'clock) and the voltage differential between ... delay to close, by doing at 11 o'clock, we are achieving closing close to 12 o'clock.