46 C.F.R. Subpart 111.12—Generator Construction and Circuits
Title 46 - Shipping
(a) Prime movers must meet part 58, subpart 58.10, of this chapter, sections 4/5C2.15 and 4/5C2.17 of the ABS Rules for Building and Classing Steel Vessels and, for mobile offshore drilling units, section 4/3.21 of the ABS Rules for Building and Classing Mobile Offshore Drilling Units. Additional requirements for prime movers for emergency generators are in part 112, subpart 112.50, of this chapter. (b) Each generator prime mover must have an overspeed device that is independent of the normal operating governor and adjusted so that the speed cannot exceed the maximum rated speed by more than 15 percent. (c) Each prime mover must shut down automatically upon loss of lubricating pressure to the generator bearings if the generator is directly coupled to the engine. If the generator is operating from a power take-off, such as a shaft driven generator on a main propulsion engine, the generator must automatically declutch (disconnect) from the prime mover upon loss of lubricating pressure to generator bearings. [CGD 94–108, 61 FR 28277, June 4, 1996; 61 FR 33045, June 26, 1996, as amended at 62 FR 23907, May 1, 1997] Excitation must meet sections 4/5C2.19.1, 4/5D2.5.1, 4/5D2.5.2, and 4/5D2.17.6 of the ABS Rules for Building and Classing Steel Vessels or, for a mobile offshore drilling unit, section 4/3.23 of the ABS Rules for Building and Classing Mobile Offshore Drilling Units, except a static exciter must not be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual magnetism type exciter that has the capability of voltage build-up after two months of no operation. [CGD 74–125A, 47 FR 15236, Apr. 8, 1982, as amended by CGD 94–108, 61 FR 28277, June 4, 1996; 62 FR 23908, May 1, 1997] Each generator must meet the applicable construction and test requirements of section 4/5 of the ABS Rules for Building and Classing Steel Vessels or, for mobile offshore drilling units, section 4/3 of the ABS Rules for Building and Classing Mobile Offshore Drilling Units. [CGD 94–108, 61 FR 28277, June 4, 1996; 61 FR 33045, June 26, 1996, as amended at 62 FR 23908, May 1, 1997] Voltage regulation and parallel operation must meet sections 4/5C2.19.2, 4/5C2.19.3, 4/5C2.21.2, and 4/5C2.21.3 of the ABS Rules for Building and Classing Steel Vessels or, for mobile offshore drilling units, sections 4/3.31 and 4/3.33 of the ABS Rules for Building and Classing Mobile Offshore Drilling Units. [CGD 94–108, 61 FR 28277, June 4, 1996; 61 FR 33045, June 26, 1996, as amended at 62 FR 23908, May 1, 1997] (a) The current-carrying capacity of generator cables must not be: (1) Less than 115 percent of the continuous generator rating; or (2) Less than 115 percent of the overload for a machine with a 2 hour or greater overload rating. (b) Generator cables must not be in the bilges. (a) Applicability. This section applies to each generator except a propulsion generator. (b) General. Each ship's service generator and emergency generator must be protected by an individual, tripfree, air circuit breaker whose tripping characteristics can be set or adjusted to closely match the generator capabilities and meet the coordination requirements of Subpart 111.51. Each circuit breaker must contain the trips required by this section. (c) Type of trips. A circuit breaker for a generator must: (1) Open upon the shutting down of the prime mover; (2) Have longtime overcurrent trips or relays set as necessary to coordinate with the trip settings of the feeder circuit breakers; and (3) Not have an instantaneous trip with the exception that an instantaneous trip is required if: (i) Three or more alternating-current generators can be paralleled; or (ii) The circuit breaker is for a direct current generator. (d) Setting of longtime overcurrent trips. The pickup setting of the longtime overcurrent trip of a generator circuit breaker must not be larger than: (1) 115 percent of the generator rating for a continuous rated machine; or (2) 115 percent of the overload rating for a machine with a 2-hour or greater overload rating. (e) Setting of instantaneous trips. The instantaneous trip of a generator circuit breaker must be set above, but as close as practicable to, the maximum asymmetrical short circuit available from any one of the generators that can be paralleled. (f) Reverse-power and reverse-current trips. Each generator arranged for parallel operation must have reverse-power or reverse-current trips. (g) Location. A ship's service generator overcurrent protective device must be on the ship's service generator switchboard. The generator and its switchboard must be in the same space. (For the purposes of this section, the following are not considered separate from the machinery space: (1) A control room that is inside of the machinery casing and (2) a dedicated switch-gear and semiconductor rectifier (SCR) compartment on a mobile offshore drilling unit that is separate from but directly adjacent to and on the same level as the generator room). (h) Three-wire, single-phase and four-wire, three-phase generators. There must be circuit breaker poles for each generator lead, except in the neutral lead. (i) Three-wire, direct-current generators. Each three-wire, direct current generator must meet the following requirements: (1) Circuit breaker poles. There must be separate circuit breaker poles for the positive and negative leads, and, unless the main poles provide protection, for each equalizer lead. If there are equalizer poles for a three-wire generator, each overload trip must be of the “Algebraic” type. If there is a neutral pole in the generator circuit breaker, there must not be an overload trip element for the neutral pole. In this case, there must be a neutral overcurrent relay and alarm system that is set to function at a current value not more than the neutral rating. (2) Equalizer buses. For each three-wire generator, the circuit breaker must protect against a short circuit on the equalizer bus. (j) Circuit breaker reclosing. Generator circuit breakers must not automatically close after tripping. [CGD 74–125A, 47 FR 15236, Apr. 8, 1982, as amended by CGD 81–030, 53 FR 17847, May 18, 1988; CGD 94–108, 61 FR 28277, June 4, 1996; 62 FR 23908, May 1, 1997] For general requirements, see §111.35–1 of this chapter.
Title 46: Shipping
PART 111—ELECTRIC SYSTEMS—GENERAL REQUIREMENTS
Subpart 111.12—Generator Construction and Circuits
§ 111.12-1 Prime movers.
§ 111.12-3 Excitation.
§ 111.12-5 Generator construction and testing.
§ 111.12-7 Voltage regulation and parallel operation.
§ 111.12-9 Generator cables.
§ 111.12-11 Generator protection.
§ 111.12-13 Propulsion generator protection.
