Motor Types and Connections
DC Series, Shunt and Compound Motors; Single-Phase and Three-Phase AC Motors; Reversing, Speed, Dual-Voltage and Delta/Wye Stator Connections
Theory from NEETS Module 5 (NAVEDTRA 14177A) chapters 2–4 read 2026-09-20 (read-log-neets.md); code references to NFPA 70-2023 Article 430 as read in read-log-2023.md · Reviewed 2026-09-21
Motor questions sit in the DBPR General Theory section (and in the Residential exam's own "Motors" subject, 4–6 items) and read like shop tasks: change the rotation of a motor, change the speed of a single-phase motor, connect a motor to run on a different voltage, connect a three-phase stator for delta or for star (wye), and install or replace each named motor type. Article 430 (the corresponding NEC lesson) tells you how to protect and wire the circuit; this lesson is the machine itself. The theory paraphrases the public-domain Navy NEETS course, Module 5.
1. DC motors — series, shunt, compound (NEETS 2.5)
| Type | Field connection | Torque and speed behaviour | Typical use |
|---|---|---|---|
| Series | field in series with the armature — few turns of heavy wire carrying full armature current | very high starting torque; speed varies widely with load; races to destruction with no load — always keep a load connected | hoists, cranes, winches, traction, portable tools (as the universal motor) |
| Shunt | field in parallel with the armature — many turns of fine wire on constant voltage | nearly constant speed under changing load (constant field flux; counter emf self-regulates armature current); moderate starting torque | machine tools, fans, pumps needing steady speed |
| Compound | both a shunt field and a series field ("long shunt" when the shunt field spans series field plus armature; "short shunt" otherwise) | shunt-motor speed stability plus series-motor starting torque under heavy load | compressors, elevators, punch presses — loads that start heavy and then run steady |
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