Definition
The process of converting alternating current (AC) generated within the armature of a DC generator into direct current (DC) at the output terminals. This is accomplished mechanically by a commutator, a segmented ring on the armature shaft, working with stationary brushes that switch the connection to each armature coil at the precise moment its current would otherwise reverse direction.
Plain English
Commutation is the trick that turns the back-and-forth current produced inside a DC generator into steady, one-direction current as it leaves the generator. A rotating switch on the armature flips the connections at just the right time so the output always flows the same way.
Context Anchor
Seen in aircraft electrical-system discussions, especially when describing DC generators, starters, starter-generators, commutators, and brushes.
Derivation
From the Latin commutare, meaning 'to change' or 'to exchange.' The commutator literally exchanges the connections to each armature coil twice per revolution, which is why the process is called commutation.
Why Pilots Care
Proper commutation keeps the generator producing clean, reliable DC power; poor commutation causes arcing, brush wear, and possible loss of electrical power in flight.
Intuition Check
Do not read commutation as communication. Communication is sending information; commutation is electrical switching inside a motor or generator.
Example Sentence 1
Worn brushes were preventing proper commutation, causing the generator output to fluctuate.
Example Sentence 2
Excessive sparking at the brushes is often a sign that commutation is not occurring cleanly.