| Unlike DC motors with brushed commutators, Tesla's polyphase AC motor's current was created magnetically, not mechanically. |
| The selection is rounded out by copper sections for starter commutators and for other auxiliary motors. |
| In the AC system, the commutators and brushes have been replaced by micro-processor controlled semi-conductors. |
| Commutation system The commutators and brushes are made of high quality precious metal alloy and provide a minimized but constant contact resistance as well as insensibility to changes in environment. |
| Each year during the summer, the DC machines are shut down for an overhaul: servicing includes changing the carbon brushes and skimming the commutators, among other things. |
| Direct current is produced by batteries, fuel cells, rectifiers, and generators with commutators. |
