In electromagnetism, excitation is the process of generating a magnetic field by means of an electric current.
A 100 kVA direct-driven power station AC alternator with a separate belt-driven exciter generator, date c. 1917
Alternator of 1930s diesel generating set, with excitation dynamo above
A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire t
Excitation (magnetic)
…electric generator or electric motor consists of a rotor spinning in a magnetic field. The magnetic field may be produced by permanent magnets or by field coils. In the case of a machine with field coils, a current must flow in the coils to generate (excite) the field, otherwise no power is transferred to or…
Modern (c. 2009) low-cost universal motor, from a vacuum cleaner. Field windings are dark copper colored, toward the back, on both sides. The rotor's laminated core is gray metallic, with dark slots for winding the coils. The commutator (partly hidden) has become dark from use; it's toward the front. The large brown molded-plastic piece in the foreground supports the brush guides and brushes (both sides), as well as the front motor bearing.
Salient field bipolar generator
Consequent field bipolar generator
Consequent field, four-pole, shunt-wound DC generator