If a motor with a rated FLA of 1 amp is drawing .9 amps, is tripping the overloads there are a few possibilities. Check the connections around the overload to make sure they are not loose or showing signs of heat. Check your ammeter to make sure it is accurate at that low of a current. Does the overload trip when you are watching or is something happening that you aren't seeing? Other than that, I would suspect a bad overload block.
Most overloads are rated for a motor with a service factor of 1.15. That is, the 125% is already calculated. It has been a very long time since I saw one that wasn't, and it was old when I saw it.
That having been said, I just put a bunch of Telemecanique overloads that nuisance tripped frequently and the commissioning people adjusted them up 25%, even though the literature indicated that was already done. I guess that, at some point, production gets priority.
I would guess that a 480 volt motor with a FLA of 1 amp would be .5 or .75 HP.
I'll leave the code questions to someone South of the 49th.
Last edited by twh; 08/13/07 09:47 PM. Reason: clarity
