Which motor provides good speed regulation?

• A. Shunt DC Motor
• B. Series DC Motor
• C. Synchronous Motor
• D. Compound DC Motor

Answer: (A)

Speed regulation is how much a motor’s speed changes as the load varies. A shunt DC motor has its field winding connected in parallel with the armature and is fed with a fairly constant field current. With the flux held nearly steady, the speed depends mainly on the applied voltage, so when load changes the speed stays almost the same. The armature current adjusts to provide the needed torque, but the speed doesn’t wander much, giving good regulation.

In contrast, a series DC motor shares the same current through field and armature, so the flux changes with load. Light load means low flux and very high speed; heavy load means high current and lower speed—resulting in poor regulation. A compound motor sits between them, offering intermediate regulation, while a synchronous motor (an AC machine) keeps speed tied to the supply frequency, but it’s a different type of machine for which regulation behavior isn’t the DC motor context here.