Figure 3.2-npicai power distribution system found In a guided missile destroyer.

to larger loads. Figures 3-1 and 3-2 are examples of

DESIGNATION

two typical power distribution systems found on some

All IC systems are identified by circuit

ships.

designations. Designations consist of single or double

Most ac power distribution systems in naval

letters as previously described in chapter 2 under the

vessels are 450-volt, 3-phase, 60-Hz, 3-wire un-

heading Cable Marking.

grounded systems.

SHIP'S SERVICE POWER

EMERGENCY POWER DISTRIBUTION

DISTRIBUTION SYSTEM

SYSTEM

The ship's service power distribution system is the

The emergency power distribution system

electrical system that normally supplies power to the

supplies a limited amount of power for ship control

ship's equipment and machinery. The ship's service

and for the operation of vital equipment when the

switchboards and associated generators are usually

located in separate engineering spaces to minimize the

ship's service distribution system fails. An emergency

possibility that a single hit will damage more than one

power distribution system is installed on most

switchboard.

combatant ships and some auxiliary ships.

The ship's service generator and distribution

This system is separate and distinct from the

switchboards are interconnected by bus ties. This

ship's service distribution generators and switch-

interconnection allows any distribution switchboard

boards. Each emergency switchboard is supplied by

to feed power from its generators to one or more of the

its associated emergency diesel generator. The

other switchboards, allowing the generator plants to

emergency feeders run from the emergency switch-

be operated in parallel. The power distribution to loads

boards and terminate in manual or automatic bus

can be directly from the generator and distribution

transfer equipment at the distribution panels or at

switchboards. The power distribution can also be from

loads for which emergency power is required.

distribution panels to small loads, or from load centers

Figure 3.2-npicai power distribution system found In a guided missile destroyer.

3-3