UFC 4-150-02
12 May 2003
3-8.6.4
Shipboard Equipment Ratings. Most ship distribution circuit breakers
operate at 440 volts and are protected with 100,000-amp, current-limiting fuses in series
with the breakers. In most cases, these circuit breakers are type AQB-LF400 as
described in NAVSHIPS Publication 362-2333, Air Circuit Breakers (Fused), Navy Type
AQB-LF400. The main breaker for the shipboard system on nuclear carriers is an air-
type breaker rated at 250,000 amps asymmetrical interrupting capacity, and without
current-limiting fuses. The shore distribution system must be designed in accordance
with MIL-HDBK-1004 series, Electrical Engineering, to ensure that available fault is
within the capability of the ship's distribution system. Contact the cognizant NAVFAC
EFD/EFA OR USACE DISTRICT for information on shoreside fault current data to
determine the required interrupting capacities and equipment design characteristics.
3-8.7
Supplemental Requirements for Nuclear Submarines (SSN, SSBN).
Nuclear submarines (SSN, SSBN) should conform to the following shore power
requirements:
3-8.7.1
Substations for 480 Volts Service. Substations serving hotel loads at
submarine piers must be designed in accordance with paragraph 3-8.5.1 for fixed
substations, or paragraph 3-8.5.3 for portable substations, and in accordance with the
supplemental requirements below. The substation's primary section should be built with
dual primary feeders. Switchgear and breaker equipment should be designed so that
automatic reset and restoration of power to submarine services will be delayed a
minimum of 5 to 10 seconds after loss of commercial power. This is required in order to
prevent damage to the submarine's electric plant equipment. The maximum time to
restore power should be 5 minutes. Provide undervoltage and underfrequency relays at
substations. Relay types and set points for undervoltage and underfrequency should be
evaluated separately for each installation and coordinated with the cognizant NAVFAC
EFD/EFA OR USACE DISTRICT.
3-8.7.2
Standby Power. Power requirements for normal operation are given in
SCDB. A permanent standby generator plant sized to provide all submarines at a pier
with emergency power for normal hotel demands should be provided at active berths.
One spare generator for each plant should be supplied. The generator plant is not
required at ports-of-call. The generator plant should incorporate automatic load
shedding and load priority selection features. Generator plants should be located
ashore whenever possible.
3.8.7.3
Maximum Downtime. At facilities where submarines are berthed, the
station's electrical utility system and the pier's electrical system should be designed to
provide a maximum downtime of 5 minutes using temporary or emergency generators,
or an alternate commercial feeder. System downtime is defined as: (1) the time
required to restore power to the pier when maintenance or repair activities are required;
or (2) the time required to transfer from one power source to another after system
disturbances. This includes the time required for protective devices to operate and the
time to start emergency generators.
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