Chapter 9—ENGINEERING CASUALTY CONTROLlighting, interior communication, electronicsequipment, and other electrically powered devices.In designing the electric plant, every effort is madeto obtain the greatest reliability and continuity ofservice possible under casualty conditions.from any live switchboard to supply power to vitalcircuits.EMERGENCY POWER SYSTEMThe distribution system forms the vital con-nection between the generators and the equipmentwhich uses electric power. The distribution of elec-trical power is generally done through either theship’s service or the emergency switchboards.Electrical power distribution may also be donethrough a casualty power circuit rigged fromeither of these switchboards.The general arrangement of the ship’s servicesystem is such that any faulty circuit will be cutout automatically, without interruption of powersupply to other circuits. This is done through theoperation of protective devices. If the ship’s serv-ice generators fail, the emergency generator isautomatically placed in operation for battle func-tions. The emergency switchboard can supplypower to all parts of the ship; however, all un-necessary circuits must be stripped from the boardwhen the emergency generator is set up inautomatic to supply emergency power to vitalequipment. If this is not done, the generator willbe overloaded and the breakers will trip out orthe diesel engine will stall.The purpose of the emergency power systemis to furnish an immediate, automatic source ofelectric power to a limited number of selected vitalcircuits. It includes one or more diesel-drivenemergency generators, the emergency switch-boards, and a distribution system, which isseparate from the ship’s service electric plant anddistribution system. Emergency feeders run fromthe emergency switchboards to at least one andusually to two different ship’s service switch-boards. Emergency power feeders for certain vitalauxiliaries are also run to control panels. Theemergency power system, with the use oftransformers, is also used for furnishing emer-gency lighting.Whenever practical, emergency generators andswitchboards are installed above the waterline, tominimize danger from flooding. Also, theemergency plant is installed as far away as prac-tical from the ship’s service plant, to avoid bothplants being put out of action by battle damage.Protection against loss of power on a ship withship’s service, emergency, and casualty powerdistribution systems is described below:On most ships, the emergency generators donot have the same capacity as the ship’s serviceplants. Therefore, care must be taken to preventoverloading the emergency generator, which inturn will overload the diesel engine.CASUALTY POWER SYSTEM1. FAILURE OF ONE SHIP’S SERVICEGENERATING PLANT. The load is trans-ferred, by the Electrician’s Mate, to the othership’s service generating plant. Care must be takento prevent overloading the generating plant thattakes over the load.The casualty power system is used to supplyemergency power for steering gear, fireroom andengineroom auxiliaries, fire pumps, drainagepumps, communications equipment, and othervital machinery needed to keep the ship afloat orto get it out of a danger area.2. CIRCUIT OR SWITCHBOARDFAILURE. Vital loads are transferred to an alter-nate feeder and source of ship’s service power bymeans of a transfer switch on the control panel.3. FAILURE OF BOTH NORMAL ANDALTERNATE POWER SUPPLY. Certain vitalequipment are shifted to an emergency feederwhich receives power from the emergencyswitchboard.4. FAILURE OF THE SHIP’S SERVICEAND EMERGENCY CIRCUITS. Temporarycircuits are rigged with the casualty power cablesThe casualty power system is a simple electricaldistribution system used to maintain a source ofelectrical supply for the most vital machinery andequipment needed to keep the ship afloat andfunctioning. This casualty power system is in-tended to supply power during emergenciesONLY. The system is purposely kept simple sothat it can be rigged quickly and with a minimumchance of error; but, the very simplicity of itsdesign limits the extent of its use.Sources of supply for casualty power use areprovided at each ship’s service switchboard and9-11
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