🔍 Key Concepts

• Short-shunt vs long-shunt compound DC motors (where the shunt field is connected in the circuit) • How to tell cumulative vs differential compounding from the direction of current through the series and shunt field windings • Current path from line + through the armature, interpoles, series field, and back to line - in figure B

💭 Think About

• Trace the exact path of current from the positive line terminal, through the armature and all field windings in figure B. Is the shunt field connected across the entire line, or only across the armature? • Compare the direction of current through the shunt field and series field. Would their magnetic effects aid each other or oppose each other? • Ask yourself: in this connection, as load current increases, would you expect the main field strength to increase (cumulative) or decrease (differential)?

✅ Before You Answer

• Identify clearly whether the shunt field is connected directly across the supply line (long-shunt) or only across the armature terminals (short-shunt). • Confirm the current direction through S1–S2 relative to F1–F2 to decide if the series field is aiding or opposing the shunt field. • Before choosing, match both features: (1) short vs long shunt and (2) cumulative vs differential; eliminate any options that get either part wrong.