Motors and generators

46 CFR §111.25-1

§ 111.25-1 -1 General requirements. The requirements for generators contained in § 111.12-5 apply to motors. [CGD 74-125A, 47 FR 15236, Apr. 8, 1982, as amended by CGD 94-108, 62 FR 23908, May 1, 1997]

46 CFR §183.320

§ 183.320 Generators and motors. (a) Each generator and motor must be: (1) In a location that is accessible, adequately ventilated, and as dry as practicable; and (2) Mounted above the bilges to avoid damage by splash and to avoid contact with low lying vapors. (b) Each generator and motor must be designed for an ambient temperature of 50 °C (122 °F) except that: (1) If the ambient temperature in the space where a generator or motor will be located will not exceed 40 °C (104 °F) under normal operating conditions, the generator or motor may be designed for an ambient temperature of 40 °C (104 °F); and (2) A generator or motor designed for 40 °C (104 °F) may be used in 50 °C (122 °F) ambient locations provided the generator or motor is derated to 80 percent of the full load rating, and…

DOE-HDBK-1011 Vol.4 §12-1

DOE-HDBK-1011 Vol.4 §12-1 — AC motor types, nameplate data, and protection AC motors drive the great majority of shipboard auxiliaries. The induction motor dominates: a three-phase stator sets up a rotating field at synchronous speed (Ns = 120f/poles) that induces rotor currents and drags the squirrel-cage rotor along at a slight slip. It is chosen for ruggedness, low cost, and needing no rotor connections. The synchronous motor runs at exactly synchronous speed with a DC-excited rotor and, when overexcited, supplies leading reactive power to correct plant power factor, but it needs a separate excitation source and a starting means. Wound-rotor induction motors allow external rotor resistance for high starting torque and speed control. A motor's nameplate fixes its rated voltage, full-loa…

NEETS Mod. 5 §1-1

NEETS Mod. 5 §1-1 — The elementary DC generator and commutation A generator converts mechanical energy into electrical energy by electromagnetic induction: when a conductor cuts magnetic flux, a voltage is induced in it whose magnitude depends on flux strength, the number of conductors, and the speed of cutting, and whose direction is given by the left-hand rule for generators. In the elementary generator a wire loop rotates between field poles; the induced voltage is inherently alternating because each side of the loop passes alternately under a north and a south pole. A DC generator makes this output unidirectional with a commutator — a split ring on the shaft whose segments, contacted by carbon brushes, reverse the external connections to the loop at the instant the induced voltage wou…

NEETS Mod. 5 §1-3

NEETS Mod. 5 §1-3 — Generator types: series, shunt, and compound DC generators are classified by how the field windings are connected relative to the armature, which determines their voltage-versus-load behavior. In a series-wound generator the field is in series with the armature and load, so field strength (and voltage) rises with load current — voltage is unstable and this type is rarely used for power. In a shunt-wound generator the field is connected in parallel across the armature and carries a small, roughly constant current; its terminal voltage falls only moderately as load increases, giving reasonably steady voltage, and it is adjusted by a field rheostat. A compound-wound generator combines a shunt and a series field: the series field's contribution grows with load to offset th…

NEETS Mod. 5 §2-2

NEETS Mod. 5 §2-2 — DC motor types and starting Like generators, DC motors are series, shunt, or compound wound, and the connection sets the speed-torque character. A series motor has very high starting torque and draws heavy current at low speed but its speed varies widely with load and it will overspeed dangerously if unloaded, so it is used for starters, hoists, and traction where it is never run unloaded. A shunt motor runs at nearly constant speed from no load to full load and gives moderate starting torque, suiting it to driving pumps, fans, and machine tools where steady speed matters. A compound motor blends the two: good starting torque from the series field with better speed regulation from the shunt field, used for loads with sudden torque demands like compressors and some winc…