INITIAL SHIPBOARD DESIGN OF THE NAVY INTEGRATED POWER AND ENERGY CORRIDOR (NIPEC)

INITIAL SHIPBOARD DESIGN OF THE NAVY

INTEGRATED POWER AND ENERGY CORRIDOR

(NIPEC)

Chapter 1

Introduction

The United States Navy, through the Office of Naval Research (ONR), is funding

research related to power distribution on next-generation ships. ONR established the

Electric Ship Research and Development Consortium (ESRDC) to encourage a

multidisciplinary approach in addressing the complexities of naval electrical systems

and to develop the tools needed to design and engineer complex systems to reduce

initial decision risk and costs. The main focus of ESRDC is the design of the Power

Electronic Power Distribution System (PEPDS). The Massachusetts Institute of

Technology (MIT) through the MIT Marine Grant Design Lab is also focused on the

development of the Naval Integrated Power and Energy Corridor (NiPEC). NiPEC is

a modular entity that can be attached directly to a ship during the construction

process, containing all the equipment for power control and distribution. Inside

NiPEC, there is a modular power conversion module (PCM) that contains the Power

Electronics Building Block (PEBB), which is a power conversion element.

The power distribution on next-generation ships will operate at higher power and

voltage levels compared to most current warships. Today's warships generally

operate with a power of between 4 to 6 MW at a voltage of 450 Volt Alternating

Current (AC). The ship in the future is planned to operate at a power of about 80

MW with voltages starting from 1 Kilovolt (kV) Direct Current (DC) (+/- 0.5 kV) to

12 kV DC (+/- 6 kV). In current ship designs, power distribution uses a point-to-

point system, where cables are connected directly from the electrical generator to the

PCM and then to the load. This approach causes the system to become less flexible

and reliable, so a better solution is needed for electrical power distribution. to PCM

to load. This leads to a less flexible and reliable system [ 14]. Therefore, a

better approach to electrical power distribution is needed.

1.1 Power Corridor Concept

The electrical corridor will include all the elements necessary to distribute

electrical power throughout the ship. These elements can include bus and conduit

cables, power converters, interface junction boxes, energy storage, circuit breakers,

and bulkhead penetration [1]. The conceptual electrical diagram of the layout of these

components is shown in Figure 1-1. The power corridor can operate with the

electrical limits of the zone which can eliminate the need for circuit breakers in each

part of the power corridor compartment.

Figure 1-1: Corridor Concept Electrical Diagram [2]

The conceptual two-dimensional layout of the required power corridor elements

is shown in Figure 1-2 and 1-3. Picture 1-2 demonstrate the concept of how all

necessary electrical elements can be physically arranged in the corridor. This set of

elements should fit inside the compartment of the vessel.

Figure 1-3 shows the final

display concept of how the four corridors can be placed inside the hull. The corridor is placed inside

the ship in such a way that it does not interfere with the structural members of the ship.

built from the hull as it can be installed without modifying the ship's structure to

increase efficiency and lower costs [1].

Figure 1-2: Side view of the Two-Dimensional Corridor Concept (Dimensions in Inches) [1]

Figure 1-3: View of the Corridor Concept Section

Figure 1-4 shows the integration of the power corridor into the notional vessel. In

this concept, there are 4 individual power corridors that run from bow to stern. This

corridor is positioned on the port side and right on decks 2 and 4 (similar to Figure 1-3).

This is done to increase the redundancy of the overall power distribution system and

reduce the volume of electrical cables required in individual corridors. In a notional

ship, each corridor is required to distribute 25 MW of power at 1000 VDC. This

allows the ship to theoretically lose one intact corridor and still operate at 100

% of electricity capacity.

In addition, Figures 1-4 show the varying number of elements in each compartment.

Discussed in more detail in Section 1.2, flexibility in the number of elements is a key

aspect in the design of power corridors.

Figure 1-4: Concept of the whole ship corridor [2]

1.2

Concept of Backup Space

Power corridors are a key aspect in ship design. The main aspects that are similar

are propulsion equipment and power plants. Therefore, the electrical corridor

requires space provided for it at the beginning of the ship's design for an optimal

electrical corridor layout. The backup room approach allows high power levels to be

safely distributed throughout the ship while building a margin for future growth in

electrical loads. Designating space for electrical components early in the design of

the ship is critical to the success of the design because the ship's power infrastructure

interacts with all electrical components. This leads to the concept of an integrated

power corridor. All electrical distribution equipment is located within the electrical

corridor with several power corridors required on board the vessel for redundancy

and electrical capacity requirements [14].

Each compartment along the corridor will have the same basic NiPEC electrical

element . The number of basic NiPEC elements in each compartment will vary

based on the electrical demand within a particular section of the vessel. The detailed

concept of arranging NiPEC components in a single compartment of a ship will

provide great value to NiPEC research because components in one compartment can

be repeated along the corridor and to other corridors within the ship.

1.3 Power Corridor with Traditional Equipment

Power corridors inherently include basically all the major components needed to

distribute electrical power throughout the ship. These components have been

identified as bus and conduit cables, power converters, interface junction boxes,

energy storage, circuit breakers, bulkhead penetration [1]. To provide the basis for

the layout of the power corridor, this thesis will develop the design of the power

corridor with existing technologies and devices. Thus the research currently being

developed on a device such as PEBB is not directly implemented here, but can be

easily replaced with the device used in this thesis when it becomes available.

NiPEC PCMs PEBB 1000 and PEBB 6000 have been researched in the past with

the Navy iPEBB being actively researched. Physical dimensions, weight, cooling

requirements and electrical operating characteristics have not been fully determined.

They are also expected to take up a significant amount of space within the electrical

corridor. By using traditional equipment as a demonstration of the NiPEC concept,

many unknowns were eliminated thus allowing the evaluation of size constraints on

board ocean vessels. Key design factors will be identified and passed on to improve

future NiPEC concepts and research.

Existing power conversion equipment for marine applications operates at

approximately 1000 V DC. ABB Company developed OMD880LC, a marine DC

distribution system that operates at 1000 V DC [10]. ABB's documentation provides

information about the concept and rough size of the equipment in DC network

drawings, but insufficient information is required to accurately model the equipment

in a 3D environment.

Another company, SATCON Technology Corp., provided a brochure that

included the size and power details of the power conversion equipment [4].

SATCON equipment is specifically designed for use on USN vessels and operates at

1000 V DC. This makes the equipment data ideal for research on future USN

electrical applications. SATCON filed for bankruptcy in 2012 and that makes it

difficult to find open source information [15]. Therefore, a copy of the SATCON

brochure has been provided in Appendix B. Measuring all ABB and SATCON data

will be

discussed further in section 3.1.

1.4 Economic Benefits of Power Corridors

By producing the power corridor from the hull, the production time can be significantly

reduced and thus the cost is also reduced. Shipbuilders often refer to the 1-3-8 rule when

calculating the construction and repair time of ships. If a component is being built or

repaired from the hull in a manufacturing facility with good lighting, ventilation,

equipment, and materials, it will take 1 hour. If the same components are being worked on

in the ship module, the same work that takes 1 hour in the manufacturing facility,

now it will take 3 hours. Finally, if this component was being worked on inside the

hull, it would now take 8 hours to complete [16].

In addition, USN does not allow the connection of electricity distribution cables

[17]. This means that all electrical distribution cables on board the current USN ship

must be run by hand through each other through the entire ship and connected to the

switchboard or the respective load.

The creation of power corridors from the hull including distribution cables, there

is a potential for great economic advantages in both time and cost.

1.5 Assumption

The following are the assumptions used through the design of this electric

corridor concept.

•

The notional vessel developed through ESRDC i s u s e d a s a p l a t f o r m

f o r NiPEC examples

–

Notional ship displacement will be 10000 tons

–

Each corridor will span 85% of the length of the ship.

•

Take advantage of the space approach reserved for corridor placement

•

Each compartment will use the same basic NiPEC electrical element

• Electric distribution bus operates at 1000 VDC

•

Multiple corridors are implemented allowing redundancy

• A total power level of 75 MW was chosen for t he design

•

All components of the used power corridor are based on existing technology

•

The corridor is designed with modularity in mind and the main components can

be assembled outside the ship

•

U.S. Navy standards and requirements are used as much as possible

Chapter 2

Model Ship

Starting with a representative ship model is essential for developing the concept

of power corridors and understanding the limitations of space inside the ship. The

concept of the power corridor is being researched for use in future USN ships and as

such, the ship model should be based on the previous USN ship design. This chapter

will discuss the development of the notional 10,000-ton ship model.

2.1

ASSETS

Advanced Ship and Submarine Evaluation Tool (ASSET) is a software developed

by Naval Surface Warfare Center, Carderock Division (NSWCCD). It is a tool used

to determine the validity of ship concepts. There are many factors that need to be

incorporated into the ASSET to produce output. These inputs are managed in ASSET

i n a h i e r a r c h i c a l d a t a b a s e w i t h t h e m a i n c o m p o n e n t s o f t h e

s h i p b e i n g t h e p r o p u l s i o n p l a n t , p o w e r p l a n t , a n d h u l l . T h e

p r i m a r y c o m p o n e n t s c a n b e f u r t h e r d i v i d e d i n t o s e c o n d a r y a n d

t e r t i a r y c o m p o n e n t s t o i n c o r p o r a t e f u r t h e r d e t a i l s i n t o t h e

m o d e l [ 18].

Important notes for future ASSET users is USN has included ASSET into a

software called Rapid Ship Design Environment (RSDE). Limitations ASSET is that

any changes to the ship's concept (speed profile, payload, hull shape, etc.) need to be

input by the user and synthesized to see if the concept is feasible.

The RSDE was developed to quickly evaluate the large concept trading space of

ships. The user can enter the desired parameters of the vessel and the RSDE will

evaluate a specific number of designs and generate a relationship between the entered

parameters and the desired output to inform designers and decision-makers [19]. In

addition, both of these programs have distribution controls placed on them and are

not available to the general public.

The special notional ship model used for this thesis was previously developed by

the Marine Grant Design Laboratory using ASSET. The hull shape and structural

layout are similar to the DDG-51 with plugs installed to increase the length and

displacement to approximately 10,000 metric tons [11]. Figure 2-1 shows the general

concept of the shape of the ship.

Figure 2-1: 3D Notional Ship Model

2.2 Dense work

Solidworks is a 3D modeling software developed by the France-based company

Dassault Systèmes. Solidworks has many tools available including structural and

fluid analysis. For Power Corridor development, the main benefit of using

Solidworks is to analyze the size and arrangement of components needed in a 3D

environment.

2.2.1

Transferring Notional Ship data to Solidworks

Most of the notional vessel structural information is taken from the hull structure

provided and hull subdivision data. The size and structural location of the ship

Members are in the hull structure data, and the location and size of the ship

compartment are in the hull subdivision data.

The structural calculation of the notional ship is carried out at the longitudinal

location (bow to stern) of the hull that is affected by the moment of the largest

sagging and bogging. Generally, these moments are the largest around the center of

the ship. The calculated structural design is at the location of 0.52. Location 0.0 is

defined as perpendicular to the front and 1.0 is defined as perpendicular to the back.

On-site

0.52 of the notional design, decks 5 and 6 were removed for structural modeling and

calculation because the center line of the ship model contained the engine room. The

machine room requires two open decks due to the size of the equipment installed.

Given the available data from the notional ship, this thesis will use the ship's

center model with decks 1, 2 and 3.

2.2.2

Modeling in Solidworks

The data obtained from the notional ship design is pulled into Solidworks to

create a 2-dimensional model (Figure 2-2).

Figure 2-2: Solidworks 2 Dimensional Structure Seen Backwards

Table 2.1 shows the dimensions of all the stiffeners used in Figure 2-2. The spacing of the

small stiffeners is the average of all stiffeners on the corresponding deck. The

notional vessel provides a more detailed assertor distance than is required for this

thesis. Flat

The spacing is acceptable for conceptual purposes because it does not

change the number of stiffeners on the deck and structural analysis is not performed.

Notional vessels contain deck plate thicknesses that vary for each deck level. Again,

since structural analysis was not performed, all plate thicknesses were set to 0.75 in.

Confesso

Web

Heigh

(in)

Web

Thickness

(in)

Flange

Widt

(in)

Flange

Thickness

(in)

Confesso

Distanc

e (

in)

Deck 1

(small)

4.75 0.25 4.0 0.25 24.5

Deck 1

(large)

15.25 0.25 5.5 0.25 196.0

Deck 2 and

3 (small)

3.75 0.25 4.0 0.25 22.0

Deck 2 and

3 (large)

11.75 0.25 4.0 0.25 22.0

Hull 3.75 0.25 4.0 0.25 15.75

Table 2.1: Notional 'T' Stiffener Dimensions

The 2-dimensional model shown in Figure 2-2 is "stretched" within Solidworks

by 6 meters (236 inches) to add a third dimension to the model. Then the 6-meter-

long section of the ship was copied linearly to provide a total of 4 compartments on

two decks. Compartment doors, a 6-foot-tall person, and a scaled model of the hull,

were added for the reference frame [20] [21]. Figure 2-3 shows a completed model of

a four-compartment ship.

2.2.3

Example of a Single Compartment Detail

Most of the work will be focused on setting up in one compartment of the ship.

All elements in one compartment can be repeated to another compartment.

Figures 2-4, 2-5, and 2-6 show the different views of the single-compartment

model. Figure 2-5 is from the point of view with the ship's centerline on the left side

and the hull on the right side. Figure 2-6 is from the point of view with the left side

Figure 2-3: Solidworks 3-Dimensional Structure

the rear end of the compartment and the right side of the front end of the compartment.

Figure 2-4: Perspective of a Rearview Compartment

Figure 2-5: One Compartment View Rear View

Figure 2-6: View of one compartment looking towards the hull

Article 3

Electrical Components of the Corridor

3.1

Power Conversion Module (PCM-1)

PCM is a power conversion module capable of taking the input voltage (either

AC or DC) and outputting another voltage (either AC or DC). PCM-1 is a PCM with

special capabilities as outlined in the "NGIPS Technology Development Roadmap"

[22]:

PCM-1: Converts 1000 V DC Power from PCM-4 to 800 VDC power, 650

V DC Power, or any other DC voltage the user requires. It also separates

and protects the Port Bus and Starboard 1000 VDC from faults in the

zone.

PCM-1 is one part of the entire ship's power generation and distribution system.

The additional power conversion module is PCM-2 and PCM-4. PCM-2 changes DC

to 60 or 400 Hertz (Hz) Air conditioning and PCM-4 repair AC power from electric

generators to DC [22].

A literature review of DC electrical systems designed to operate on ocean liners

resulted in the results of two companies. The PCM of these companies is a possible

replacement for what can be achieved with the technology that exists today. The first

is from ABB, a company headquartered in Zurich, Switzerland that specializes in

electrification and automation. They designed an ocean DC microgrid that operates at

1000 VDC [ 10]. The 3D rendering of ABB PCM i s s h ow n i n t he F i g u re

3-1. The middle of the module contains 5 individual power conversion sections with

the outer section containing switching and control equipment. The technical data for

ABB PCM are listed in Table 3.1.

Figure 3-1: ABB PCM [3]

Dimension 85" (2154 mm) W

33" (827 mm) D

51" (1294 mm) H

Input Voltage

750-1000 V DC

Power Conversion

5 sections 100-650 kW

Tabel 3.1: ABB PCM Data [9] [10]

The second company to produce results on marine DC electrical systems

Boston, MA-based SatCon Applied Technology. SatCon PCMis specifically designed

for

USN use. Their PCMs were built to military specifications and tested at the Naval

Surface Warfare Center, Philadelphia Division (NSWCPD) in Philidelphia, PA.

There is limited data available from open source on SatCon military equipment as the

company filed for bankruptcy in October 2012 and switched from military

applications [15]. Thus, all data for SatCon equipment are derived from the brochure

attached in Appendix B. The main data of SatCon PCM-1 taken from the SatCon

brochure are summarized in Table 3.2.

Dimension 96" W, 48" D and 75"

Input Voltage

925 – 1035 V DC

Output Voltage

350 – 800 V DC

Power Conversion 9 parts rated 125

kW (total 1125 kW )

Tabel 3.2: Data SATCON PCM-1

Built SatCon PCM-1 shown in Figure 3-2 being tested in NSWCPD. The SatCon

PCM-1 has four cabinets with a width of 24" associated with it giving the final

dimensions of 96" W, 48" D and 75" H. This height does not include the structural

foundation for PCM-1. Nine power conversion parts can fit inside PCM-1. These

parts can be changed as seen in the Figure 3-3.

Figure 3-2: SATCON PCM-1 [4]

Figure 3-3: SATCON PCM-1 Conversion Parts [4]

ABB and SatCon PCM power conversion densities can be compared to understand

ft3

the current state of marine power conversion technology. The general equation used

to calculate the power conversion density is equation 3.1. The results for each PCM

model are shown in Table 3.3. Especially ABB PCM and SatCon PCM-1 have a

power density of 7.9 and 5.6

Power Conversion Density = Maximum Power Converted

Total PCM Volume (3.1)

Total

Volume

PCM (ft3)

Maximum

Converted

Power (kW)

Power

Conversion

Density

(

)

ft3

ABB PCM

82.8 650 7.9

SatCon PCM-1

200 1125 5.6

Table 3.3: PCM Power Density

Due to the specific information about the internal layout of the second

PCMlimited, it is assumed that the power density of the power conversion section

between the two models is similar. Power density differences listed in the Table 3.3

c a n b e a t t r i b u t e d t o t h e d i f f e r e n t l ay o u ts a n d e q u i p m e n t u s e d i n

t h e s w i t c h in g a n d c o n t r o l p a r t s o f t h e P C M .

Given that ABB and SatCon PCMhave the same power conversion density, but SatCon

PCM-1 is built for USN purposes and meets the requirements of military shock and vibration

specifications, SatCon PCM-1 was chosen as the basis for implementation in the power

corridor. The base values are listed in Table 3.2.

3.2

Power Conversion Module (PCM-2)

The PCM-2 is a power conversion module to convert 800 VDC to 3 phase 450 V

AC. The SATCON brochure in Appendix B lists the DC to AC inverter part has a

conversion capacity of 112.5 kW and conforms to the same modular layout as the

DC to DC c onverter in the PCM-1. Table 3.4 summ ari zes the PCM-2 data.

In this power corridor concept, the PCM-2 is assumed to have a width of 24

inches and a small AC power requirement. If additional AC power is required, more

conversions

sections can be added.

Each PCM-2 conversion part requires an associated PCM-1 conversion part .

PCM-1 is required to lower the voltage of a 25 MW Bus from 1000 V to 800 V for

use by PCM-2. See Figure 3-17 for an output electrical connection diagram.

Dimension 24" W, 48" D and 75" H

Input Voltage

800 V DC

Output Voltage

450 V AC

Power Conversion 1 section rated at 112.5 kW

Tabel 3.4: Data SATCON PCM-2

3.3

Cable

The size of electrical cables for electrical corridors is calculated based on the

thesis Impact of Electrical Standards on the Size of Electrical Cables of MVDC

Ships by Joshua Malone [5]. The key information taken from the thesis is the size of

the cable conductors, the thickness of the cable insulation, the number of conductors

in a single cable, and the distance of the cable group.

3.3.1

Input Cable

The input cable is the main distribution cable throughout the ship. Based on the

power corridor concept discussed in Section 1.1, there will be four electrical

corridors that run along the length of the ship. Two power corridors will be placed on

the second deck on the port side and right and two power corridors will be placed on

the fourth deck on the port side and right. Each corridor is required to distribute 25

MW of power at 1000 VDC. This allows the ship to theoretically lose one intact

corridor and still operate at 100% electrical capacity.

Malone's thesis focuses on the calculation of groups of 4 wires (2 pairs of 2 wires

with opposite polarities) as they are likely to be used on future USN vessels to

minimize inductance and magnetic signatures [23]. The maximum current of

individual conductors in groups of 4 wires is calculated for different conductor sizes

(8.25-25.4 mm). The

𝑚

DC Single

Cable

The maximum current value is based on the analysis of the heat dissipation of the 4-

wire group and ensures the cable does not exceed the operating temperature of 90°C

[5].

The maximum conductor size (25.4 mm) analyzed in the Malone Thesis was

chosen to minimize the total number of wires in the electrical corridor. Since the input

cable is the main distribution cable, it will run along the corridor. Malone's thesis

calculates the maximum permissible current in a 25.4 mm conductor (1000 All Wire

Gage (AWG)) in a group of 4 cables operating on 12 Kv is 654 Amps. The 654 Amp

limit also applies to operating voltage 1 Kv based on equations 3.2. The heat

generated in a conductor is based on the current and resistance of the cable and not

the operating voltage of the cable [5].

Group 4-Heat Generated DC Cable (W)

4 *

* R

(3.2)

IDC

Single Wire

DC Current per Wire (Amp)

RDC = Cable Resistance to Direct Current(

)

𝑚

The insulation thickness of a single conductor is based on the operating voltage of

the cable. Malone's thesis evaluates Cross-Linked Polyethylene Insulation (XLPE)

insulation thickness required at various stresses on land and ship applications. This is seen

in the Picture 3-4. The ship application curve (100% and 133%) converges at

about 2.25 mm at 1 Kv.

Figure 3-4: Comparison of Applicable Reference Average Insulation Thickness in

Ship and Land-Based vs. Un [5]

Based on military specifications and research, several additional layers are required

around a single conductor. All concentric layers are summarized in Table 3.5. The total

diameter of a single cable is calculated to be 34,726 mm and rounded to 35 mm for ease

of modeling as 34,726 mm is the minimum thickness required.

Conductor Diameter [5] 25.4 mm

Father Semi-Condutor

Thickness [23]

0.127 mm

Insulation Thickness [5] 2.25 mm

Silicone rubber or Fiberglass

Tape thickness [24]

2,032 mm

Two or more Cross-Lapped

Semi-Conductor Tape Thickness

[24]

2,032 mm

Total Single Cable Diameter 34,726 mm

≈

35 mm

Table 3.5: Input Cable Single Wire Data

Four 35 mm cables can then be bundled together to create a group of 4 cables.

Group 4 wires are encased in multiple layers of material summarized in Table 3.6.

Single Cable Diameter

35 mm

Father Semi-Condutor

Thickness [23]

0.127 mm

Braided 34 AWG armor [23] 0.4064 mm

Pita Polyester [23] 0.127 mm

Cross-Linked Polyolefin Jacket

[24]

2.2.286 mm

Total Diameter Group 4 Cables

90.4

Table 3.6: Entering 4-Cable Group Data

A cross-sectional view of a group of 4 wires is shown in Figure 3-5 (not scaled).

Figure 3-5: Cross-section of Group 4-Input Cable (not scaled) [5]

The total electric current required to distribute 25 MW at 1kV is shown in Equation

3.3.

I (Amp)

(Watt)

(Volt)

25,000,000 (Watts)

1000(Volts)

25, 000(Amps) (3.3)

By utilizing the maximum current from Equation 3.3 a n d t h e m a x i m u m

c u r r e n t p e r w i r e ( 6 5 4 A m p s ) , t h e t o t a l n u m b e r o f c o n d u c t o r s

c a n b e c a l c u l a t e d ( s h o w n i n E q u a t i o n 3.4).

Number of Conductors =

Total Arus (Amps)

Maximum Current Per Cable (Amps)

25,000 (Amps)

654 (Amps)

38.2

Conductor

(3.4)

Finally, taking into account that the DC cables are ope rati ng in pa irs and

the inpu t ca bles will b e b undl ed i nto g rou p 4, th e tot al n umb er of

grou p 4 inp ut ca bles is ca lcu lat e d (s hown i n E qu atio n 3.5). The total

number of 4-wire groups required is 19.1 rounded down to 19 4-wire groups for even

multiples of 4. The rounding of the number of 4 cable groups to 19 is done due to

spacing constraints which will be discussed further in Chapter 4 Section 4.3.

Rounding the number of 4-wire groups to 19 increases the maximum current per wire

to 658 amps. This 4 amp increase from the maximum of 654 amps discussed in

Malone's thesis is considered acceptable because Malone's thesis states his

calculations appear to be conservative [5].

Number of Groups 4 Cables Total Conductor 2 C a b l e s P e r

P a i r

4 Cables Per Group

2 Cables Per Pair

38.2 *

4 wires per group

= 19.1 Group 4-Cable

≈ 19 Group 4-Cable

(3.5)

Cable spacing needs to be taken into account to ensure proper heat dissipation.

IEEE Std. 45.8 states each cable group should be spaced

2.15 times the diameter of a single cable [25]. The cable is spaced 1,075 times the

diameter of a single cable from the surface of any ship [5]. Table 3.7 lists the

distances required for group 4 cables.

Distance between 4-groups

Cable

75.25 mm

Distance between 4-groups

Cables and Ship Surfaces

37,625 mm

Table 3.7: Group 4-Input Wire Spacing

Picture 3-6 shows the arrangement of 19 groups of 4 cables. More details on this

arrangement are discussed in the Section 4.3.1.

Figure 3-6: 25 MW Bus Arrangement

3.3.2

Output Cable

The output cable is the cable that will connect the output PCM-1 to the load.

Because PCM-1 has nine individual power conversion sections with a value of 125

kW, can support nine individual loads each at its own voltage level. To design an

output cable that can support all possible voltage outputs from the PCM-1, a

conservative output voltage of 1000 VDC is selected. Distributing 125 kW at 1000

VDC r e q u i r e s t h e c o n d u c t o r t o s u p p o r t 1 2 5 a m p s a t t h e o n e

s e e n i n E q u a t i o n 3.6. From Malone's Thesis, a single wire at 1/0 AWG (8.25

mm diameter) has a maximum amplitude of 187 amps [5].

I (Amp)

(Watt)

(Volt)

125,000 (Watts)

1000(Volts)

125(Amps) (3.6)

The calculation of the total cable diameter is similar to the Input Cable in Section

3.3.1 with the exception that this will be a group of 2 cables. A group of 2 wires is

necessary because DC cables operate in pairs with positive and negative polarity.

The concentric layers of a single conductor are summarized in Table 3.8. The total

diameter of a single cable is calculated to be 17,576 mm and rounded to 18 mm for

ease of modeling as 17,576 mm is the minimum thickness required. Layer 2 of the

bundled cables is summarized in Table 3.9. The final diameter of the group of 2

wires is rounded to 42 mm for easy modeling as 41.89 is the minimum diameter.

Conductor Diameter [5] 8.25 mm

Father Semi-Condutor

Thickness [23]

0.127 mm

Insulation Thickness [5] 2.25 mm

Silicone rubber or Fiberglass

Tape thickness [24]

2,032 mm

Two or more Cross-Lapped

Semi-Conductor Tape Thickness

[24]

2,032 mm

Total Single Cable Diameter 17.576 mm

≈

18 mm

Table 3.8: Output Cable Single Wire Data

As in the Section 3.3.1, the minimum distance between the cables needs to be

calculated for heat dissipation. Table 3.9 lists the required spacing for group 2 cables.

The two distances listed are rounded to facilitate modelling as this is the minimum

distance required.

Single Cable Diameter

18 millimeters

Father Semi-Condutor

Thickness [23]

0.127 mm

Braided 34 AWG armor [23] 0.4064 mm

Pita Polyester [23] 0.127 mm

Cross-Linked Polyolefin Jacket

[24]

2.2.286 mm

Total Diameter Group 2 Cable 41.89 mm

≈

42 mm

Table 3.9: 2-Cable Group Data Output

Distance between 2-groups

Cable

38.7

≈

40 mm

Distance between 2-groups

Cables and Ship Surfaces

19.35

≈

20 mm

Table 3.10: Group 2-Output Cable Spacing

3.3.3

Clamp cable

All cables on board USN n e e d t o b e s e c u r e d f o r t h e s a f e t y o f y o u

a n d e q u i p m e n t a n d t o m a i n t a i n p r o p e r c a b l e s p a c i n g f o r h e a t

d i s s i p a t i o n . M i l i t a r y S p e c i f i c a t i o n 2 1 9 1 9 p r o v i d e s d e s i g n

r e q u i r e m e n t s f o r c a b l e c l a m p s [ 26]. Cable clamps are designed using this

specification based on the outside diameter of the cable that needs support. Three cable

clamp models are built in Solidworks to support a 4-wire input group (90.4 mm outer

diameter), a single input cable (35 mm outer diameter), and a group of 2 output cables

(42 mm outer diameter). Picture 3-7 shows an example of a cable clamp modeled in

Solidworks.

Figure 3-7: Example of a Solidworks Cable Clamp

3.3.4

Minimum Wiring Bending Radius

MIL-STD-2003-4B Standard Method for Power Plant Installations for Surface

Ships and Submarines (Cableways) stipulates "the radius of the conductor's bend

shall not be less than eight times the outer diameter of the conductor, as measured

around the jacket of the individual conductor" [27].

The bending radius of the cable that is of major concern is the 4-wire input group

and the single input cable. These two cables need to be routed within the limited

space of the electrical corridor. The 4-wire input group runs the length of the ship

and requires a bend to be routed to the Interface Box mounted on top of the PCM-1.

The input single cable needs to be routed inside the Interface Box. The Interface Box

will be discussed further in Section 3.4. The bending radius of group 2 of the output

cable will not have an input cable space limitation because it will not be routed

within the power corridor, but it is still important when developing a corridor layout.

Table 3.11 shows the minimum bending radius calculated for each wire of concern.

Input 4-Cable Group

723.2 mm

Single Cable Input

280 mm

2-Cable Group Output

320 mm

Table 3.11: Minimum Cable Flex Radius

By using the minimum known radius on the Table 3.11, relationships are

developed (Equations 3.7) to connect the vertical offset between two points and the

minimum horizontal distance required between the two points so as not to violate the

minimum bending radius of the cable. The definition of offset and separation is

shown in Figure 3-8.

Figure 3-8: Definition of Offset and Separation

In Equation 3.7,

is the minimum bending radius of the constant cable,

is the offset

between two points, and

the minimum distance required between two points in

order not to violate the minimum radius. Equation 3.7 applies to 0

≤

2r. As

becomes larger past 2r,

remains constant.

for

𝑦=

√︁−x2︁

+ 4√r2x2 (3.7)

≤

Figure 3-9 shows the relationship between the desired offset and the minimum

separation required not to violate the minimum bending radius of the cable.

Figure 3-9: Minimum Cable Bending Radius

3.4 Interface Box

The interface box will provide space to connect and route power from the

distribution bus 25 MWt o PCM-1, and group 2 output cables. Inside the interface

box there will be a DC isolation switch to isolate the power from 25 MW

distribution bus to PCM-1. The interface box will be physically installed on top of

the PCM-1 inside the power corridor. Since there is little open-source information

about marine 1000 V DC switches , the next best option is to research industrial

land-based DC electrical equipment.

3.4.1

Isolation Switch

An electrical isolation switch may be required in the interface box in order to

isolate the PCM-1 from the 25 MW distribution bus. Each PCM-1 can have two

power sources for redundancy. The isolation switch will allow the operator to choose

between power sources. The power source will be a single group of 4 input cables as

each group of 4 input cables has a power capacity of 1.3 MW based on the

calculations in Section 3.3.1. This is larger than the PCM-1's power capacity of

1,125 MW. To create redundancy to the PCM-1, two 4-wire input groups are routed

into the interface box.

Marine DC isolation switches typically have a rating of 12-48 VDC which is

well below 1000 VDC of the power corridor. The beach-based technology has an

isolation switch with a rating of up to 1000 VDC. A system study is required to

determine whether this switch will disconnect without load or full load.

The global company Siemens has a large open source database available with

information about their products. Researching their online databases and product

catalogs, a suitable DC isolation switch was found. Two-pole, single-throw isolation switch

is chosen because one switch can isolate positive and negative cable pairs. In addition, the

isolation switch can operate with remote actuation to improve the reliability of the system. The

operator does not need to be physically present at the electrical corridor section to realign power

for maintenance or casualties.

The Siemens 3KD Switch Disconnectors model series was chosen as a

replacement and represents what can be achieved with today's off-the-shelf

components. These switches are rated to 1000 VDC and 1600 amps. 3KD Switch

separators are manufactured in 3 to 6 pole variants [28]. Siemens has 3D models of

their products available for download. Figure 3-10 shows the 3DK 3 Pole Switch

Splitter.

Figure 3-10: Siemens 3KD 3 Pole Switch Splitter [6]

The model seen in Figure 3-10 is modified in Solidworks into the 2-pole design

shown in Figure 3-11. One pair of terminals on the isolation switch will be connected

to the tee connector (discussed in Section 3.4.2). The other pair of terminals will be

connected to the riser connection of the interface box connecting the isolation switch

to the PCM-1's internal bus.

Figure 3-11: Siemens 2KD Pole 3 Series Switch Trigger

3.4.2

Connector Tee

The connection between the 25 MW distribution bus and the isolation switch will

be made with a tee connector. The tee connector will allow the isolation switch to tap

to the 25 MW distribution bus without cable termination. The electrical insulation

will be removed from the conductors of the individual input cables and the tees can

be clamped onto the cables. The tee will be bolted to a DC isolation switch that

creates an electrical connection between the 25 MW distribution bus and the isolation

switch.

The PT Connector series from Greaves Corporation was found as a suitable base

for the design of tee connectors. The Greaves connector is shown in Figure 3-12.

Figure 3-12: Greaves PT Series Tee Connectors [7]

Greaves tee connector design is modified so that it can fit into the confined space

of the interface box and bolted to the isolation switch. The Solidworks tee model is

shown in Figure 3-13. The brown cylinder through the center represents one

conductor of the uninsulated input wire, and the yellow, green, and 4 larger blue bolts

are the clamping mechanism to the conductor. The smaller bolt at the bottom is the

connection point to the isolation switch.

Figure 3-13: Solidworks Tee Model

Picture 3-14 and 3-15 shows the two bolted tee connectors to the insulation switch

and the electrical riser connection of the insulation switch to PCM-1.

Figure 3-14: Solidworks Top View Isolation Switch with Connection

Figure 3-15: Solidworks Bottom View Isolation Switch with Connection

3.4.3

Layout

The layout of the interface box is designed in such a way as to minimize cable

bending to ensure that the cable does not violate the minimum bending radius

requirements of the USN cable (discussed further in Section 3.3.4), observe the

minimum electrical creep length, and the components are placed for ease of access

during maintenance. The overall dimensions of the interface box are 96" W, 48" D,

and 7" H.

The USN requirements for electric propagation in the revised MIL-DTL-917 F

(Detailed Specification Basic Requirements for Electrical Power Equipment) are based

on the operation of

voltage, operating volt-amperage, and whether the electrical component is enclosed

[17]. A single conductor power corridor can operate at 1 kV, 658000 volt-amps, and

is enclosed. Based on these factors, the minimum electric creep length is 1.5 inches.

It is this length of electrical propagation that drives the required distance between the

exposed conductors at different potentials. This includes the required distance

between the positive and negative cable terminals and the distance from the exposed

conductor to the ground potential. Historically, USN ships have used a non-landed

system with landings used for safety. Therefore, the zero potential of a ship is the

hull of the ship and anything that is electrically connected to it. In the case of power

corridors, the metal cover of the electrical components is considered on the potential

of the ground.

Figure 3-16 shows a diagram of the electrical connections inside the interface box to

the PCM-1 internal bus.

Figure 3-16: Electrical Diagram of the Interface Box

Figure 3-17 Demonstrate the concept of all major connections in PCM-1. Power is an

introduction to the internal PCM-1 Bus of 25 MW B u s ( a s s e e n i n t h e

P i c t u r e 3-16) and distributed to nine power conversion sections inside the PCM-1.

Each conversion part has its own associated output connection to the load.

Figure 3-17: Electrical Diagram of Output Connection

Picture 3-18 shows the top view of the Solidworks Interface Box model. Grids

overlaid on the Figure 3-18 is a 6 x 6 inch grid. Shown in the Picture 3-18 from left

to right are two groups of 25 MW 4 yellow cables which are divided into positive

and negative cables respectively. One set of cables is shaded lighter than the others

for easy visual understanding of the cable group. Each pair of wires (black and red) is

connected to its isolation switch. At the bottom of the Image 3-18 is the nine output

connections PCM-1.

Figure 3-18: Top View Solidworks Interface Box (6 x 6 in grid)

Figures 3-19 a n d 3-20 s h o w t h e p e r s p e c t i v e v i e w o f t h e i n t e r n a l

l a y o u t o f t h e i n t e r f a c e b o x .

Figure 3-19: Perspective View of the Solidworks Interface Box

Figure 3-20: Perspective View of the Solidworks 2 Interface Box

Figures 3-21 and 3-21 show different perspectives of the interface box with the

lid attached. The cover is installed during the operation of the electrical corridor and

is only removed for maintenance and inspection.

Figure 3-21: Perspective View of the Solidworks Interface Box Cover Mounted

Figure 3-22: Solidworks Interface Box Perspective View Enclosure Mounted 2

3.5 Barrier Connection

Bulkhead connection is a method of connecting power corridors between

compartments. These connections will be semi-permanent to allow the installation of

25 MW electric corridor Bus sections one at a time. This is different from how cables

are traditionally installed on ships. Traditionally, cables are installed by manually

running each cable from the start point to the end point. This can lead to long,

potentially ship-long cables, passing through many compartments and bulkheads.

Traditional wiring methods require a lot of human manpower. As discussed in Section

1.4, there are economic benefits that can be obtained by constructing electrical

corridor components from the hull in the workshop. The semi-permanent 25 MW Bus

connection allows the bus to be built from the hull with other power corridor

components, then a section of the electrical corridor is attached to the ship and

plugged in.

There are companies that specialize in high voltage and current connections.

Pfisterer has developed a medium-voltage connection system with a rating of up to

52 kV and can be operated in marine environments [29]. These connection systems

are physically too large to be used in electrical corridors, but they provide insight

into connection systems developed to operate in marine environments.

TE Connectivity has developed a connection system with a lower voltage rating

of 12 kV [8]. No details have been given about the use of this connection system in

the marine environment, but it is reasonable to assume the connection system can

works in the marine environment due to its physical similarity to the Pfisterer system.

Figure 3-23 shows a diagram of TE Connectivity's cabling system used for reference

in modeling power corridor connections. This connector model is rated at 12 kV and

1250 amps. Since the connectors in the power corridor only need to support about

half of this current, all dimensions in Figure 3-23 are scaled in half to provide a good

estimate of the space required for the connectors.

Figure 3-23: TE Connectivity Connection System Diagram [8]

Figure 3-24 shows a model of a Solidworks plug. The plug will be installed as a

termination to a group conductor of 4 single input wires. The plug is approximately 4

inches long (excluding the wires shown in the image) and the mounting bracket is 2 by 2

inches square. Figure 3-25 shows a cross-sectional view with the labels of the main

components required for the function of the plug.

Figure 3-24: Plug Perspective

Figure 3-25: Plug Cross Section

Figure 3-25 shows a perspective view of the socket connections. The socket will

connect the two plugs together (one plug on each side). It will be manufactured in

such a way that all internal parts are continuous to reduce electrical resistance at the

joints and outside the socket is properly isolated from the operating bus voltage.

Figure 3-26: Socket Perspective

Figure 3-27 shows a cross-sectional display with the main component labels required for the

socket function. The central copper plug is to prevent water from flowing from one compartment

to another on flood victims.

Figure 3-27: Socket Cross Section

Figures 3-29 and 3-28 show the coupling of plug and socket connections and

associated cross-sections. The plug will be held in place by four bolts. Socket

connections will be installed in the bulkhead to connect neighboring electrical

corridor sections.

Figure 3-28: Plug and Socket Cross Section

Figure 3-29: Plug and Socket Perspective

The plugs and sockets are combined together to form a module that fits into a

group of 4 wires. The module is then formed into an assembly to be installed on the

bulkhead as shown in Figure 3-30 and 3-31. The separation between the end of the

group of 4 yellow insulated wires and the beginning of heat shrinkage is 6 inches to

meets the minimum cable bending radius requirements (Section 3.3.4). The bulkhead

assembly plate measures a rectangle of 55.7 by 20.5 inches.

Figure 3-30: Full Bulkhead Connection View

Figure 3-31: Full Block Connection View 2

3.6

Connected Load

3.6.1

High Power Load

Included in the same compartment of the power corridor can be some potential

representative load for PCM-1 to master. Table 3.12 list some USN cargo that

It has been used in previous research on notional ship design for electric corridors.

Operating voltages are not provided but for conceptual purposes, it is assumed the

load is operating at different voltages.

Carry Power

Active Denial System (ADS)

600 kW

Multi-Function Dual-Band

Radar

5 MW

Integrated Radio Frequency

(RF) Suite

2 MW

Table 3.12: Notional Ship Cargo [11]

3.6.2

Hotel Load

It is reasonable to assume that internal PCM-1 There may be one or two

additional power converters if there are none PCM-2 connected to provide AC power

conversion. Additional converters can be rated around 5-10 Kw. They can power on

PCM-1 control circuit, communication cabinets, and/or space and cabinet lighting.

Picture 3-32 shows an example of an additional converter electrical diagram and

potential connections.

Figure 3-32: Hotel Load Electrical Diagram

Article 4

Assembling Electrical Components

into Corridors

Chapter 3 discusses the main components that will be included in the power

corridor. This chapter will discuss the arrangement of all components in the power

corridor within the available space.

To help with the orientation of the model, there is a 6-foot tall person facing the

centerline of the ship holding a scaled model of the ship. Figure 4-1 shows a

perspective view of the entire model with a 6-foot person and a scaled boat. The deck

above the people and the harbor hull are hidden in this picture. Figure 4-2 shows a

zoomed-in view of Figure 4-1.

Figure 4-1: 6-foot Person Perspective Display

Figure 4-2: 6-foot person magnified perspective view

4.1 7-inch foundation

Most settings in the power corridor are centered around the placement PCM-1

within the power corridor. It is the largest component with many electrical

connections and cooling water. The deep design into the cooling system is beyond

the scope of this thesis but space is provided for the cooling water pipes, valves, and

connections.

In this concept, the cooling water pipe is placed under the PCM-1. The space

above the PCM-1 is intended for the 25 MW Bus (discussed in Section 4.3). The

PCM-1 is raised 7 inches above the deck to allow for 6 inches for cooling pipes and

an additional 1 inch for the supporting material in the foundation. The size of the

cooling water pipe is discussed in Section 4.4.

Figures 4-3 and 4-4 show the front and side view of a 7-inch foundation with

dimensions. The foundation is 144 inches long to fit the 96-inch PCM1 plus another

48 inches for the communication cabinet and PCM-2 cabinet. The communications

cabinet will be discussed further in Section 4.2.2 and PCM-2 in Section 4.2.3. The

foundation is 48 inches deep to fit the cabinet.

Figure 4-3: 7 in the Foundation Side View

Figure 4-4: 7 on the Foundation Front View

Picture 4-5 shows a perspective view of the entire 7-inch foundation. The foundation is

colored to allow for easier viewing within the Solidworks model. Picture 4-6 shows the

placement of a 7-inch foundation inside the model boat. A foundation distance of 7

inches from the hull corresponds to the required maintenance access space between

PCM-1 and the stomach (discussed further in the Section 4.2.1) and the placement of

Bus 25 MW (discussed further in the Section 4.3).

Figure 4-5: 7 in Foundation Perspective View

Figure 4-6: 7 in a Foundation Ship Placement Perspective View

The 7-inch foundation is designed to place the structural members of the 7-inch

foundation perpendicular to the ship's structural members. This is done to distribute

the weight of the 7-inch foundation and the installed cabinets evenly. The structural

members of the ship run from bow to stern and the structural members of the 7-inch

foundation run from the harbor to the right.

4.2

Cupboard

4.2.1

PCM-1

PCM-1 placed in such a way that there is sufficient space between the PCM-1

and the hull for access by maintenance personnel. MIL-STD-1472 (Human

Engineering) identifies the minimum walking floor width for a person to walk on a

catwalk and carry a tool or equipment as 18 inches [30]. While the walkway between

the PCM-1 and the hull is not located on the catwalk, it provides the minimum

walking space needed. MIL-STD-1472 also stipulates "A minimum of 0.4 square

meters (m2) (4.0 square feet) of floor space per person shall be reserved for

maintenance personnel and their clothing (including necessary personal protective

equipment, equipment, and equipment) as well as free space for movement and

activities necessary to perform maintenance duties" [30].

The Naval Marine Systems Command (NAVSEA) Technical Publication T9640-AC-DSP-

010/HAB (Ship Habitability Design Criteria and Practice Manual) stipulates that secondary

walkways must be not less than 30 inches wide and the width of the main road within the

anchorage area must not be less than 36 inches [31]. While the footpath between

The PCM-1 and hull are not anchored areas, it provides a good basis for the width of

the walkway to ensure adequate personnel access to the equipment.

Most of the maintenance is expected to be done on the side of the PCM-1 facing

the ship's centerline. The PCM-1 hull side access is expected to be used primarily for

periodic inspection of equipment. Any electronic equipment that needs to be repaired

or replaced is expected to occur from the side of the PCM-1 ship's centerline. This

side is expected to have more space as it opens to a larger aisle or personnel

compartment.

Figure 4-7 shows the placement of the PCM-1 cabinet on a 7-inch foundation. The

distance of the 7-inch foundation and PCM1 from the hull at deck level is 33 inches.

The distance between the PCM1 and the hull increases with the height above the deck

as the hull curves out of the keel of the ship to the weather deck. A distance of 33

inches from the hull was chosen to maximize volume above the PCM-1 for the 25 MW

Bus (discussed in Section 4.3). 33 inches exceeds the 30 inches of secondary walkway

specified in the NAVSEA Technical Publication T9 6 4 0 - A C - D SP - 0 10 / H AB

V es s e l L i v a b il i t y D es i g n Cr i t e r i a a nd P r ac t i c e M a n u a l. D u e t o t h e

l en g t h o f t he w a l kw a y o n t h e h ul l s i d e of the PCM-1, there is room for

multiple maintenance personnel (4.0 square feet) as specified in MIL-STD-1472

Human Engineering.

Figure 4-7: PCM-1 Perspective Display (Colored Orange

4.2.2

Communication and Control Cabinet

Additional cabinets were added to the power corridor model to represent the

space required to house communication and control equipment in this section of the

electrical corridor. In maintaining the modular footprint of the electrical corridor, the

communication and control cabinet measures 24 inches wide by 48 inches deep by 75

inches high. This allows the cabinet to be placed next to the PCM-1. The

communication and control cabinet is shown next to the PCM-1 in Figure 4-8.

Figure 4-8: Communication and Control Cabinet Perspective Display (Yellow)

4.2.3

Kabinet PCM-2

A third cabinet was added to the power corridor model to represent the space that

could accommodate the PCM-2 cabinet. In maintaining the modular footprint of the

electrical corridor, the communication and control cabinet measures 24 inches wide

by 48 inches deep by 75 inches high. This allows the cabinet to be placed next to the

PCM-1. The PCM-2 cabinet is shown next to the PCM-1 in Figure 4-9.

Figure 4-9: PCM-2 Perspective View (Purple)

4.2.4

Interface Box

The interface box is mounted on top of the PCM-1. The design of the internal

components of the interface box is discussed in Section 3.4. Figure 4-10 shows the

interface box mounted on top of the PCM-1. Figure 4-11 shows an interface box

installed with the cover attached.

Figure 4-10: Interface Box Perspective Display

Figure 4-11: Interface Box Perspective Display with Cover

4.3

Bus 25 MW

4.3.1

Cable Configuration

The 25 MW Bus cable shall fit over and within the footprint of the PCM-1 while

also maintaining the required distance from the group of 4 cables as discussed in

Section 3.3.1. The most compact arrangement of the 25 MW Bus is determined as a

triangular packing arrangement.

Figure 4-12 shows the 25 MW Bus array . The cables are arranged in an

equilateral triangular matrix. The distance of one group of 4 wires from the other

group is 6.6 inches from center to center. This maintains the cable-to-wire distance

calculated in Section 3.3.1 for heat dissipation.

Figure 4-12: Final view of the 25 MW bus setup

Picture 4-13 showing the obstacles around Bus 25 MW . There is no group of 4

wires in the middle of the top row due to the structural 'T' beam. This 'T' beam is the

reason in Section 3.3.1 The number of groups of 4 wires is rounded to 19 wires

instead of rounding to 20 wires.

Due to space constraints, the current design of the 25 MW Bus does not meet the

required distance between the 4-cable group and the surface of the ship (Table 3.7).

The distance between the bottom 4 wire group and the top of the Interface Box is 0.5

inches. The distance between the group of 4 outer wires of the top row and the 'T'

beam is 1.0 and 1.4 inches. The required distance is about 1.5 inches

Figure 4-13: 25 MW Bus Freeway

4.3.2

Cable Support

Support for Bus 25 MW is achieved by constructing a metal support structure

around a group of 4 wires and securing the wires with cable clamps (cable clamps

discussed in Section 3.3.3). Picture 4-14 showing the arrangement of Bus 25 MW with

metal supports and cable clamps. The top and middle rows have a vertical thickness

of 0.5 inches and the bottom rows have a thickness of 0.25 inches to allow for a small

gap between the bottom of the support and the top of the interface box. The entire

support structure has a depth (into the courtyard) of 0.5 inches. No structural or

weight analysis is completed on the cable and cable support.

Figure 4-14: 25 MW Bus Support and End Display Clamps

Figure 4-15 shows a perspective view of a 25 MW Bus section with supports and

cable clamps. The length of the group of 4 yellow wires is 16 inches. This

corresponds to

the minimum possible distance between cable hangers specified in MIL-

STD-2003-4B

to avoid an excessive number of cable hangers [27].

Figure 4-15: Perspective view of a 25 MW bus

Part of the 25 MW Bus will have only 17 4-cable groups as two of the 4-cable

groups will be routed to PCM-1. Figure 4-16 shows the installation of a straight

section of a 25 MW B us o n to p o f the PCM-1. Figure 4-17 i s a n e n l a rg e d

v e r s i on o f F i g u r e 4-16. The 17 4-wire groups are in the cable support because

the two 4-wire groups are routed in and through the PCM-1. It can be seen how the

25 MW Bus fits around the ship's green structure.

Figure 4-16: 25 MW Bus End View Power Corridor

Figure 4-17: Power Corridor of 25 MW Enlarged Final View Bus

Picture 4-18 and 4-19 shows a perspective view of the straight section of Bus 25 MW

above PCM-1.

Figure 4-18: 25 MW Power Corridor Bus Perspective View

Figure 4-19: Perspective view of a 25 MW power corridor bus 2

4.3.3

Barrier Connection

Bulkhead joints are installed on the bulkheads between the compartments of the ship.

As discussed in Section 3.5, bulkhead joints are installed on rectangular plates. Holes

for the connection plates are made in the bulkhead and welded into place. In order

not to interfere with the 'T' beam passing through the bulkhead, the placement of the

bulkhead joint plate is located under the 'T' beam. Figure 4-20 shows the installation of

the bulkhead connection plate with Figure 4-21 showing the enlarged version. These figures

show the bulkhead connection plate installed under the 'T' beam and the cable support installed

to support the protruding cable.

Figure 4-20: Power Corridor Ship Bulkhead Connection View Rear View

Figure 4-21: Power Corridor Ship Bulkhead Connection Enlarged View Rear View

Figure 4-22: Power Corridor Ship Bulkhead Connection Perspective Display

Figure 4-23: Enlarged Perspective Display Power Corridor Ship Bulkhead

Connection

A second bulkhead connection plate is added on the front side of the compartment for

connection to adjacent compartments. This is shown in Figure 4-24. The bulkhead joints

are at the same height above the deck and the distance from the ship's centerline.

Figure 4-24: Power Corridor Two Ship Bulkhead Connection Perspective View

4.3.4

Curved Parts of the Cable

The straight sections of the 25 MW Bus, the Interface Box, and the Block

Connection are all connected by a group section of 4 curved cables. The cable curve

distance is measured to ensure that it does not violate the minimum bending radius

requirements discussed in Section 3.3.4. Figures 4-25, 4-26, and 4-27 show a

perspective view of a continuous 25 MW Bus.

Figure 4-25: Perspective view of a sustainable 25 MW bus

Figure 4-26: Perspective view of a sustainable 25 MW bus 2

Figure 4-27: Perspective view of a sustainable 25 MW bus 3

Figure 4-28 shows the view from the port side towards the ship's centerline of a

continuous 25 MW Bus. From this view, it can be seen that the 25 MW Bus cable

line can be seen. Figures 4-29 and 4-30 show an additional view of the port side.

Figure 4-28: The side of a 25 MW bus port continuously looking towards the ship's

centerline

Figure 4-29: Side of a 25 MW bus port continuously looking towards the centerline

of ship 2

Figure 4-30: Side of a 25 MW bus port continuously looking towards the ship's

centerline 3

4.4

Cooling Water Piping

Current research on the cooling system needed for the electrical corridor has an

outer diameter of about 5 inches of cooling water distribution pipe and a chilled

water plant located outside the corridor space [32]. The piping also needs to be

insulated to maintain the cooling power temperature and to prevent condensation

from forming on the outside of the piping and causing corrosion. Table 4.1 lists the

required insulation thicknesses of MIL-STD-769 Insulation and Lagging. The

electrical corridor can be placed inside the hull and operate in an air-conditioned

room at temperatures of 41 to 125 degrees Fahrenheit. This assumption requires an

insulation thickness of 0.5 inches. This means that the cross-sectional diameter of the

cooling pipe and its insulation will be about 6 inches.

Table 4.1: MIL-STD-769 Insulation Thickness

Picture 4-31 Demonstrate the concept of the location of supply and return of the

cooling water piping. Picture 4-32 shows a zoomed-in view of the Image 4-32. The

interface between piping and cooling components is not modeled. There are spaces

inside the corridor on both sides of the cabinet for valves and control manifolds to

control the flow rate of the cooling water.

Figure 4-31: Cooling Pipe Perspective Display (in Blue)

Figure 4-32: Enlarged Cooling Piping Perspective Display (Blue)

Article 5

Covering Power Corridor

The electrical corridor is enclosed to protect the equipment from dust and

contaminants and a barrier to the safety of personnel due to the high operating voltage.

The military requirement in designing the enclosure was that during normal operations,

personnel only needed to access the corridor from one side [33]. Other military

requirements for cages

is that all parts must be accessible for periodic inspection and maintenance [27].

5.1

Front Side of Power Corridor

5.1.1

Cabinet Access

The front side of the cabinet (PCM-1, PCM-2, and Communication Cabinet) will

have an access door. MIL-STD-1472 (Human Engineering) stipulates "When a

hinged door is in close proximity, it must open in the opposite direction to maximize

accessibility". Figures 5-1 and 5-2 show the placement of the equipment access door

on the front side of the cabinet. Each door is 24 inches wide by 75 inches high. The

black rectangle in the center of each door is the doorknob. The side opposite the door

handle is the hinged side of the door. Each door will have a catch to hold it open

while operating at sea [30].

Because there is a high voltage operating behind the cabinet doors, each door

requires an impassable interlock. This interlock will prevent personnel from

accessing the

equipment inside when energized. In addition, there will be a mechanism to energize

the lighting of the internal cabinets when the equipment doors are opened [30]. On

the outside of each door, a hazard sign will be installed to identify the high voltage

inside [33].

The status displacy is installed on the second door from the left in Figure 5-2.

This will allow personnel to understand the general status and health of the

components inside while conducting frequent inspections around the ship.

Figure 5-1: Cabinet looking towards Port Hull

Figure 5-2: Cabinet appliance door looking towards Port Hull

5.1.2

Aisle Door

A personnel aisle door is installed at the front of the cage. This allows personnel

to access the back side of the power corridor (the area between the power corridor

and the hull). Figure 5-3 shows the placement of the hallway door. This door

It is 75 inches tall and 26 inches wide in accordance with the ship's habitability

standards [31]. The door hinge is on the left side of the door when viewed in Figure

5-3. The door swings inward (towards the hull) to avoid traffic disruption of the track

[31]. The door is 4 inches away from the left bulkhead for human engineering

requirements [33].

Figure 5-3: Aisle door looking towards Port Hull

5.1.3

25 MW Bus Cover

Bolt cover is installed on top of Bus 25 MW to allow for periodic inspection and

maintenance of the cable [27]. Picture 5-4 shows installation of bolted covers over Bus

25 MW. For conceptual purposes in this model, there is no structure behind the cover

to install bolts. Potential attachment points can use the 25 MW behind the cover. The

cover is not mounted on top of the Interface box because the Interface Box has its

own cover for the output connection.

Figure 5-4: 25 MW bus bolt cover looking towards Port Hull

The top of the 25 MW Bus can be seen on 5-4 as the overhead vessel structure is

hidden in this view. Showing the vessel structure in Figure 5-5 shows how the cover

extends to the 'T' Beam of the vessel structure.

Figure 5-5: Rear-facing 25 MW bus bolt cover

5.1.4

Welded panels

In the section of the electrical corridor where access is not required or required,

welded panels are installed. Picture 5-6 and 5-7 indicates the installation of welded

panels (dark green).

Figure 5-6: Welded Panel (dark green) Looking Toward Port Hull

Figure 5-7: Welded Panel Looking Back

5.2

Power Corridor Back Side

In this concept, the back side of the power corridor is the side between the cabinet

and the hull. The minimum space required for personnel access between the closet

and the hull is 30 inches according to habitability standards [31]. The distance

between the back side of the corridor and the hull of the ship in the concept is within

33 inches.

5.2.1

Bolt Cover

Bolt covers are installed to cover all cabinets, the 25 MW Bus , and part of the

cooling water pipes. This allows access to all components for maintenance and

inspection while still providing protection from foreign objects. Figure 5-8 shows

installation of bolted covers on the back side. In this view the front of the cover is

hidden. Similar to Section 5.1.3, the top of the 25 MW Bus can be seen as the

overhead structure of the ship is hidden in this view.

Figure 5-8: Rear side bolt cover looking towards the ship's centerline

5.2.2

Sidewalk

Two walkways were installed to protect the cooling water pipes from personnel

stepping on them. The first walkway is parallel to the hallway door and is the only

walkway required within the electrical corridor. The second walkway is optional and

provides workspace for personnel if there is space on the opposite side of the

corridor. Figure 5-9 shows the placement of the trail.

Figure 5-9: The walkway facing the ship's centerline

5.3

Complete Enclosure

The following pictures show the finished electrical corridor with the cover and the

hidden structure of the ship.

Figure 5-10: Finished Enclosure Looking Back

Figure 5-11: Finished Cage Forward

Article 6

Integrating Corridors into Ships

The completed power corridor concept from Chapter 5 can be integrated into the entire

ship. As discussed in Section 1.2, space will be reserved inside the ship for the power

corridor in the design phase of the ship. The space provided for the electrical corridor

will be maintained throughout the life of the ship. This builds a margin for future

upgrades of electrical components.

6.1

Ship Parts Display

The section of the corridor modeled in Chapter 5 is located on the port side of the

ship's 2nd deck. In Figure 6-1, this will be the upper right corridor. Integrating a

complete power corridor section into the ship, adding a power corridor on the right

side of the second deck, and the port side and the right side of the fourth deck. This

physical separation allows the various parts of the ship (and power corridors) to

sustain damage and not affect the operation of the undamaged parts.

Figure 6-1: Rearview Power Corridor Section Display

Figure 6-2 shows a view of the perspective of the ship section. This part of the

ship comes from the center (bow to stern) of the ship.

Figure 6-2: Perspective View of the Rearview Power Corridor Section

Figure 6-3 shows a side view of the part of the ship looking from the port to the right

side. This display shows decks 2 through 5.

Figure 6-3: Side View Power Corridor Section Looking Port to the Right

6.2

Whole Ship View

Figures 6-4 and 6-5 show the integration of the power corridor to the entire hull.

Decks 2 and 4 are shows and decks 1 and 3 are hidden in the model. For simplicity in

this concept, the 25 MW Bus i s n o t s h o w n e x t e n d i n g f r o m b u l k h e a d t o

b u l k h e a d i n s i d e e a c h c o m p a r t m e n t . T h e l e n g t h o f t h e 2 5 MW Bus

is the same as the length described in Chapter 5. In a fully completed corridor, the 25

MW Bus and cooling water pipes can run along the corridor at the overhead level

and deck respectively. Power corridor sections are not placed in each compartment to

demonstrate the flexibility of the PCM location.

Figure 6-4: Rearview view of the ship's power corridor perspective

Figure 6-5: Forward view of the ship's power corridor perspective

Figure 6-3 shows the side view of the ship facing the port to the right. In this view

the outline of the hull and superstructure are displayed.

Figure 6-6: Side View of the Ship Power Corridor Looking Port to the Right

Figure 6-7 shows a top-down view of the power corridor inside the ship. In

this case

See only the hull and bulkhead shown. Individual decks and superstructures are

hidden.

Figure 6-7: Upper and Lower Ship Power Corridor View

6.3

Modularitas

Integration of power corridors into the vessel shown in Section 6.1 and 6.2

Demonstrate one concept of electrical corridor layout with all sections of the corridor

having the same size PCM1 and PCM-2. A more realistic concept can have a cabinet

PCM-1 and PCM-2 with different sizes depending on the power requirements in the

part of the ship.

For example, a ship will have a higher power demand near the larger load described

in Table 3.12. The part of the power corridor closest to this load will require more power

conversion sections in the PCM-1 and/or power from multiple corridors to meet the

power demand of this load. Since the spare room approach is used when designing ships

with power corridors, more PCM-1s can be installed to meet the power demands of the

ship section.

6.4

Redundansi

There are several ways redundancy is built into the electrical corridor. The first

way is that each section of the power corridor in the compartment has two power

sources connected to it as described in Section 3.4. A group of 4 wires from a 25

MW Bus is required to fully power the PCM-1. The Interface Box has two groups of

4 wires from the 25 MW Bus .

In addition, inside the Interface Box, each pair of wires (positive and negative) of

the 4-wire group has its own isolation switch to the PCM-1. The isolation switch on

each cable pair offers and an additional layer of redundancy as one damaged cable

pair does not affect the other cable pairs in a group of 4 cables. The PCM-1 can still

be fully powered from two groups of 4 wires each with one working pair of wires.

Another way redundancy is built into electrical corridors is that loads can be

powered from multiple corridors. If the entire electrical corridor is not working, the

load can be powered from other operating corridors. This is especially important for

vital loads such as the Multi-Function Dual-Band Radar (5 MW) and the Integrated

Radio-Frequency (RF) Suite (2 MW). By powering this load from more than one

power corridor, it reduces the likelihood that a single failure in the power corridor

will affect the operation of this equipment.

6.5

Reliability

Reliability is built into the power corridor both through the Redundancy

discussed in Section 6.4 and the physical separation of the power corridors from each

other. This physical separation reduces the likelihood that an event that damages one

power corridor affects the other.

6.6

Space Distribution

6.6.1

Distribution of Corridor Space in Notional Ships

The total adjustable floor area and total adjustable volume of the notional vessel

are 48804 ft2 and 574375 ft3 respectively [11]. The floor area and volume required

for one notional power corridor compartment is approximately 79 ft2 and

701.3 ft3 each. Table 6.1 shows a summary of the dimensions of the notional power

corridor in a single compartment.

Length (Bow to stern) 19.7 feet

Width (Port to Right)

4.0 feet

Tall 8.9 feet

Floor area 78.8 ft2

Partition Area 35.6 ft2

Volume 701.3 ft3

Table 6.1: Dimensions of the Notional Power Corridor, One Compartment

Assuming half of the electrical capacity of 75 MW The vessel is intended for non-

propulsion electrical loads, about 33 sections of the notional power corridor compartments are required.

Table 6.2 shows the spatial distribution of the 33 compartments of the notional power corridor to the

notional ship.

Notional Ship

33 nosional

Power

Corridor

Compartment

Ship Fragments

Space

Floor area (ft2)

48804 2600 5.3 %

Volume (ft3) 574375 23143 4.0 %

Table 6.2: Corridor Space Allocation in Notional Ships

6.6.2

Distribution of Component Space in Notional Power

Corridors

Using corridor floor area and bulkhead and volume values in Table 6.1, Table

6.3 i n d i c a t e s t h e f r a c t i o n o f s p a c e r e q u i r e d i n e a c h c o r r i d o r b y e a c h o f

t h e s i x c o r r i d o r s

Component. The area and volume for the cooling pipes assume a floor area of 7

inches high by 48 inches wide that runs at deck level along the corridor.

Fraction of

Corridor

Partition Area

Fraction of

Corridor Floor

Area

Fraction of

Corridor

Volume

Bus 25 MW

(including air

gap for heat

dissipation)

16.6 % 96.3 % 16.2 %

1.125 MW

PCM-1

70.2 % 40.6 % 28.5 %

112.5 kW

PCM-2

70.2 % 10.2 % 7.1 %

Interface Box

6.6 % 40.6 % 2.7 %

Communication

and Control

Cabinet

70.2 % 10.2 % 7.1 %

Cooling Pipe 6.6 % 100 % 6.6 %

Table 6.3: Component Space Distribution in Notional Power Corridor

Compartments

Article 7

Conclusion and Future Work

7.1 Conclusion

This thesis examines the initial physical layout of electrical corridor sections in

the compartments of generic naval ships using existing technology. Using the

technology available today, the benchmark is set on the size and power conversion

density of the power corridor components. These benchmarks will help guide the

design and sizing of future components such as iPEBB that are currently under

development.

The designed power corridor section includes all the major components required

for operation. This includes wiring, DC and AC power conversion, connections, and

space for corridor control equipment. The corridor section is sized to convert 1,125

MW of DC power into nine lower DC voltages using the PCM-1. The size of the

PCM-1 varies which means that the cabinet size can be increased or decreased

depending on the available space, power, and voltage requirements of the equipment

connected to the corridor section. PCM-2 was also introduced to activate power for

AC loads.

The relative amount of volume occupied by the different main power elements in

the corridor section is shown in Table 7.1.

ft3

Component Fraxie Corridor

Volume

25 MW Bus (including

air gap for heat

dissipation)

16.2 %

1.125 MW PCM-1 28.5 %

112.5 kW PCM-2 7.1 %

Interface Box

2.7 %

Communication and

Cabinet Control

7.1 %

Cooling Pipe 6.6 %

Table 7.1: Volume fractions of power corridor components

7.2

Future Jobs

One of the future research areas is to increase the voltage of the 25 MW Bus .

For example, increasing a 25 MW Bus to 6000 VDC lowers the total current

by a factor of 6. A single group of 4 wires operating at 6000 VDC can have

roughly the same power capacity as six groups of 4 wires operating at 1000 VDC.

Malone's thesis shows, in general, that higher operating voltages correlate with lower

bus cross-sectional area and volume required [5].

In addition, increasing the voltage can reduce the weight of the copper cable. For

the design in this thesis, a 25 MW Bus cable is assumed to run 85% of the length of

the ship or 436 feet. The diameter of the conductors is about 1.0 inches and there are

a total of 304 wires in the four notional power corridors. It gives a volume of 723 ft3

of copper. The density of copper is about 558.2 lb/ft3. Thus, the total weight of

copper in the bus cable is 403,565 pounds or 0.18 kilotons, and

hence 0.0018% of a 10-kiloton ship. A six-fold increase in bus voltage would thus

reduce the copper weight of the bus, for the same power, by a factor of 6 to just 0.03

kilotons.

The second area of future research could have to do with the size and capabilities

of future power conversion equipment. For example, the Navy's iPEBB, which is

currently under development, can reduce the total volume and area of spare space

required in the electrical corridor. The power conversion density of the PCM-1 is 5.6

kW. iPEBB

ft3

currently has a power conversion density about twice that of PCM-1. A

power conversion density of 11.2 kW can reduce the amount of notional power

corridor compartment is half. The sixteen compartments of the notional power

corridor in a notional ship can take up 2.6% of the ship's floor area and 2.0% of the

total volume of the ship.

The final area of future research is understanding the volume required in the

power corridor for the cooling pipes and the associated connections to the PCM. The

size of the pipe is assumed to be 5 inches in diameter based on the previous thesis.

Given that the cooling system is being actively researched based on the PEBB 1000

and PEBB 6000 cooling requirements, the layout of the power corridor

compartments needs to include this data.

Note that any opinions, findings, conclusions, or recommendations expressed in

this thesis are those of the authors and do not necessarily reflect the views of the U.S.

Navy.

INITIAL SHIPBOARD DESIGN OF THE NAVY INTEGRATED POWER AND ENERGY CORRIDOR (NIPEC)

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