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close this bookElectrical Machines - Basic vocational knowledge (Institut für Berufliche Entwicklung, 144 p.)
close this folder7. Single-phase alternating current motors
close this folder7.4. Single-phase commutator motors (universal motors)
View the document7.4.1. Assembly
View the document7.4.2. Operating principles
View the document7.4.3. Operational behaviour
View the document7.4.4. Technical data

7.4.2. Operating principles

The rotational direction of a direct current motor changes either when the rotor current I2 changes its direction (-M = C · F · (-I)) or the exciter current alters in the exciter winding (-M = C · (-F1) · I2).

Where both values change, which corresponds to exchanging the conductor mains of a direct current series motor, then the motor retains its rotational direction:

M = C · (-F1) · (-I2)

Therefore a single-phase commutator motor also operates in case of alternating voltage.