I believe you can correct the problem of the AI placing 3 arrays on a ship, by calling for just one of the abilities on the component not each of the 3 - or alternatively, call for none of the abilities and use an AI tag on it.
Edit:
However, since I believe the sensor array requires both sensors and combat support techs, I could see a minor problem if the AI researchs one of them some time before the other, that it may not design ships with offense/defense abilities depending on the ability that is called for in the design creation file. Although this can be solved by telling the Federation research file to research sensors first, and only using the "combat to hit offense plus" ability in the design creation file. Therefore, the AI would use combat sensors when they are researched, and then as soon as combat support is researched the Sensor Array becomes available and the AI will use that component instead because of its slightly better attack rating. Of course, this is just a theory.
[ March 03, 2004, 11:42: Message edited by: Captain Kwok ]