Animation 01: Motor and Generator Action

A clear cross-sectional view of a simple DC machine. The rotor conductors move around the shaft, a physically correct open-ended single-turn armature winding is shown beside the section. Its two winding ends connect directly to the two commutator segments, and generator mode compares split-ring DC output with slip-ring AC output.

N S Magnetic field, B: N → S Neutral axis / commutation zone SHAFT Electromagnetic torque Instantaneous action Maximum torque position A: current out, force upward B: current in, force downward Torque level: 100% Split-ring commutator and fixed brushes Fixed brush Fixed brush DC supply +− External output +DC Brush contact: normal Single-turn armature and commutation Coil, shaft, ring segments and brushes move together N S Magnetic field N → S Rotating armature Coil end A Coil end B Direct: End A → Segment A Direct: End B → Segment B A B Fixed brush Fixed brush + − DC load External current remains in one direction Brush + contacts Segment A The winding is open between its two terminals; there is no tapped closed loop. After half a turn, the same shaft direction continues while the segments exchange brushes. Therefore the external brush polarity still remains + on the left and − on the right. Out of screen • Into screen × Magnetic force
North poleSouth poleArmature conductorCommutation zone

Quick Check

1. Which parts remain fixed while the rotor turns?

2. Why is torque momentarily zero at the neutral axis?

3. What is the purpose of the split-ring commutator in motor mode?