I have a vacuum that trips the AFCI device of the circuit that services my bedroom.
The vacuum has some age on it, and there is some wear on the motor's commutator. This wear causes electrical arcing which, to the AFCI device, looks to be approaching an unsafe condition. It is not an unsafe condition, however, because the arching is internal to the motor and the wear is part of the motor's design. This knowledge, along with the fact that it sucks dirt really well, leads me to the conclusion that the vacuum is functioning properly.
The AFCI device has been engineered to detect the type of arcing caused by electric motors. Although it occasionally trips when my older vacuum is in use, it does not trip when my neighbor's new vacuum is plugged into the bedroom circuit. The device trips when it senses a potentially dangerous (although not dangerous) arc in my older vacuum, but also is able to distinguish the arc caused by by my neighbor's vacuum as from a motor and not dangerous. This information leads me to beleive that the AFCI device is functioning properly.
Should I get rid of the vacuum? I don't want to do this, because it sucks up dirt really well. Also, if I get a new one, it will wear in a year or two and cause the same problem. Should I get rid of the AFCI device? I don't want to do that, because I want protection from fires and it is required by NEC.