INSULATED BUS PIPE (IBP) FOR SHIPBOARD APPLICATIONCopyright Material IEEE

Paper Number PCIC-2006-23

Moni IslamNorthrop Grumman Ship Systems5100 River RoadAvondale, LA 70094504-654-2287Moni .islam@ngc.com

Richard WorthNSWCCD/NAVSEA,Philadelphia, PA 19112215-897-7163Richard .worth@navy. mil

Charles SmithNorthrop Grumman Newport News4101 Washington Ave,Newport News, VA 92886,757-380-2340Charles.smith@ngc.com

Abstract - The commercial shipbuilding industry and the U.S.Navy have decreed that the aim of the "All Electric Ship"power system design will be for survivability and continuity ofelectrical power supply. In general, ship service electric powerand electric propulsion power requirements are approachinghundreds of megawatts. There are major challenges to theuse of standard cable at medium voltage levels onboard dueto cable stiffness, and cable bend radius requirements fordistributing very high current around the ship. This paperexamines the practical design and installation benefitsassociated with IBP as a possible alternative to shipboardelectric power cable. Although IBP is widely used in the utilityindustry, the shipboard use of IBP is limited to severalpassenger cruise ships. No military shipboard installationshave been performed to date. This paper examines themethodology of using IBP on shipboard applications andrecommends procedures to follow at the preliminary conceptphase of ship design.

This paper recommends that the proven IBP prototypes andtheir models be the procurement specifications. The paperalso recommends:* Inclusion of IBP application recommended practices in

shipbuilding standards such as IEEE-45 and IEEE-1580* Inclusion of IBP in ABS rules for commercial ships, ABS

NVR for naval vessels, and other national andinternational shipbuilding rules and regulations.

Index Terms - IP - Ingress Protection (IEC terminology),GIS-Gas insulated switchgear.

I. INTRODUCTION

Ships are space constrained and weight sensitive vehicles.All systems have to adhere to guidelines for the ship in thesetwo areas. The All-Electric Ship requires large amounts ofelectric power to be moved about the ship. Electrical cablecan do this job but has started to present problems in that thecable runs are using valuable space and compromising thearrangement ability for equipment. Electrical cable has nowbecome a major weight item on ships that compromises theamount of other stores on the ship. The paralleling of morecables than ever before for shipboard use has becomenecessary to distribute the increasing required shipboard

power. Due to exceedingly large bend radii (8 times outsidediameter) and long cable termination installation time, whichcan be as much as eight hours per termination, the installationof cabling for these high power applications may be aninsurmountable task for the ship builder. The installation timefor IBP would be considerably less. A cost savings would berealized as a result of this reduction in production time.

What is IBP: The IBP is a commercially available means oftransmitting high current and voltage of up to 8000 amps at123 kV per single-phase section. The conductor is made upof an electrolytic copper rod or of a cylindrical aluminum tubeof alloy type AC 041. The insulation lies directly on theconductor and consists of wrapped paper dried under vacuumand impregnated with epoxy resin. Conductive grading layersare embedded during the wrapping in the insulation for fieldcontrol. The earth layer is entirely embedded in the insulationand provides a complete electrical screen. A corrugatedprotection tube of synthetic resin material, or an optionalstainless steel jacket, covers the length of the IBP on thesurface of the insulation. This protection tube provides aneffective barrier against moisture ingress and mechanicaldamage. Furthermore, the corrugation provides an increase ofthe creeping resistance on the end of the IBP. A detailedcross section of an IBP is shown in Figure 1. The single IBPsare manufactured in lengths of 6 to 10 meters.

Figure 1: Basic IBP Construction

1-4244-0559-9/06/$20.00 ©2006 IEEE

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II. GENERAL INSTALLATION DETAILS OF IBP

For longer bus runs or tight place conditions where only shortpieces can be installed, the single IBPs are joined together onsite. The bolted connection on the IBP is a flat bar solidlyconnected to the center conductor. A flexible laminatedconnector is bolted to the flat bar ends of the IBP. Aninsulating cylinder shown in Figure 2 electrically andphysically shields the joints. A ground wire keeps theconnection tube and the bolted IBPs at the same earth value.

Flexible Cu laminate connection

FullyInsulated & capacitiIvely gradedFullyrInulaelycpactielygrdeCapaitrive grading ensuresthe Fully Insukfield strength a interface between graded Coitwo insulating materialsis constant ......no flashover

monitor the bolts underneath cylinders and the boltsconnecting to other equipment. The IBP vendors requireLoctite 243 to be used on bolt threads to prevent anyloosening of bolts (verified by U.S. Navy Shock & Vibrationtesting).

The single IBPs are custom made and theirinstallation consists mainly of the easy assembly of standardcomponents. IBPs with tight bend radii of 4 times the outsidediameter are possible. The typical bending radius for cable (8times outside diameter) does not apply as the bends arecustom made for the installation and are bolted connections.A 90-degree bend for a multi-phase IBP configuration isshown in Figure 4.

ated & capacitively)nnecting Cylinder

Figure 2: IBP Connecting Cylinder

Figure 4: IBP Installation-90 Degree bend

Because IBP is treated as pipe or cable the standardbulkhead penetrators can be used in the same mannerpenetrators are used on standard cable. A typical bulkheadmounted IBP installation, with connecting tubes and entry intopower equipment is shown in Figure 5.

Figure 3: IBP Connection Detail

The IBP busbars are joined with two flexible copper laminatesections that allow for mechanical stress relief and thermalexpansion and contraction. This connection point is sealedwithin the watertight sealed insulating cylinders. Theconducting spring contacts are used to keep the inner jacketof the insulating cylinders at the same potential as theconductor. Since all sections are bolted together, no specialtools are necessary for assembly, as shown in Figure 3. Forlong term operation & maintenance, DNV (commercial marineproject certifying authority) states that an infrared thermo-graphic scan every 2 -3 years is necessary to condition

Figure 5: IBP Installation- with pipe joints

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Ill. IBP-TECHNICAL DATA

1 - IBP Dimensional tolerance of the bar length

The adjustment of the length occurs in the insulating cylindersthrough the use of flexible connectors.

2 - IBP Testing I Quality assurance

Each single bar is subject to a routine test schedule, whichconsists of: Measuring of Capacitance, insulation quality,partial discharges and nominal frequency withstand voltagetest. Each GIS connection part is pressure tested to check itssealing properties.

3 - IBP Protection class

- IP 54 is available as standard and IP 68 is available onrequest.

4 - IBP Allowed temperature range

From (- 40° C) to (+ 105 °C).

TABLE 1: Marine Installation of IBP -Cruise ships

a- Solid, separately isolated phase bus, fully grounded forpersonnel safetyb - Safe service conditions, even in high ambient humidityc - Partial discharge free operationd- Compact dimensions, tight bend radii of 4 x diametere- Link between SF6 insulated and oil insulated equipmentf- Suitable for complete outdoor installation - High short-circuitcapabilityg- Custom engineered for each individual installationh- Operation at ambient temperature down to - 40 °C(upon request - 50 °C)

i- No gas over pressure in the outdoor porcelain, eliminatesthe danger of explosion

j- Ability to match with all types of Gas Insulated Switchgear(GIS) equipmentk- Factory testedI- Easy installation; supports modular shipboard constructionand electrical pre-testing of individual modules

IV. IBP Marine Installation Data

Shipboard Application of IBP -Land based installations ofIBP, such as industrial facilities and electric power utility sub-stations have been in service for over 50 years world wide.Shipboard applications of IBP have only been in service forabout 12 years in passenger cruise ships. The cruise shipshipbuilders have taken advantage of the IBP's tight bendradii to deliver power to space constrained areas of the shiprequiring high power (i.e. podded electric propulsion motors).IBP was used in cruise ships powering around 20MW pershaft for twin shaft application. Some of the recent IBP cruiseship installations are listed in Table 1.

V. IBP ADVANTAGE OVER CABLE

Advantage of IBP over Cable -

Where shipboard high power and high ampere transition isnecessary, IBP offers many advantages over conventionalcable.

a. Cable selection (3 Phase, 60Hz)

TABLE 2: Cable Installation

Listed in Table 2 are sample cable types for four differentvoltages. For a typical 20MW power transmission with250MCM cable, total number of conductors needed at 3.3KVsystem is 42, where as for a 13.8kV system, the total numberof cables is 12.

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Country KV Amps Delivery IBP ProtectionBuilt Year Length-

(M)Germany 12 2100 2000 112.5 IP67

Germany 3.6 3640 2000 652.8 IP67

Germany 3.6 3460 2001 475.0 P67

Germany 12 2100 2001 108.0 IP67

Germany 3.6 3460 2001 525.0 P67

Germany 3.6 3460 2003 542.0 P67

Germany 12 2100 2003 91.0 IP67

Germany 3.6 3460 2003 534.0 P67

Germany 12 2100 2002 91.0 IP67

Germany 3.6 3460 2002 534.0 IP67

5 - IBP Features:

Pwr KV Amps Cable CndMW Type

1 20 3.3 4374 5KVT- 42250(14)

2 20 4.16 3467 5KVT- 30250(10)

3 20 6.6 2187 8KVT- 18250(6)

4 20 13.8 1060 15KVT- 12250(4)

b. Circuit breaker selection (3 Phase, 60Hz)

Power KV Amps BreakerMW LTD -Amp

1 20 3.3 4374 5000

2 20 4.16 3467 3600

3 20 6.6 2187 2200

4 20 13.8 1060 1200

TABLE 3: System Circuit Breaker SelectionListed in Table 3 are sample protective device requirementsfor three different voltages. For a typical 20MW power levelprotective device, the setting is 1200 Amps. For the samepower level at 3300 Volts the circuit breaker trip setting wouldbe set at 5000 Amps.

c. IBP Selection (3 Phase circuits)

TABLE 4: System IBP selectionListed in Table 4 are sample IBP selections for three differentvoltages. For a typical 20MW power transmission, the totalnumber of IBPs' needed for a 3300V system is 3 at 5000Amps, and for a 13.8kV system the total number of cables is 3at 1200 amps.

d. IBP Installation Modularity - BP supports modularconstruction, including full function electrical pre-testing ofindividual modules.

e. IBP in utility industry- IBPs have been used in the utilityindustry for many years. In recent years there arerequirements to replace open bus bar type transmission linewith IBP with protective cover such as stainless steel tomitigate susceptibility.

f. IBP in marine industry- IBPs are widely used in cruiseships with integrated electric plants. The ships with IBP arelisted in Table 1.g. IBP watertight integrity - With the use of watertightbulkhead penetrater and with IBP being a solid the watertightintegrity is not compromised.

h. IBP - blast and fragmentation survivabilityThe IBP was evaluated during Navy live ordnance testing.Test results provided a COTS IBP survivability andvulnerability baseline data point.

i. IBP bend radii - As little as 4 times outside diameter.

j. IBP certification process for Navy shipboardinstallation-

The following tests have been performed by NSWCCD oncommercially available IBP samples in FY05:

- 3 hour Gas Flame Circuit Integrity Test- Shrinkage test- Acid gas equivalent test- Halogen content test- Smoke index test- Toxicity index test- Watertight integrity test- Partial discharge test- AC voltage withstand test- Basic Insulation Level test- 3 phase bolted fault test- Free air ampacity test- EMI radiated Mil-Std-461E (RE101)- Shield continuity test- Conductor resistance test- MI L-Std-901 D Shock test- MIL-Std-167-1 Vibration test- Ordnance Survivability tests

Tests results were evaluated by NAVSEA for Navy shipboardcertification. Military standard shock and vibration have beenapproved for unrestricted Navy shipboard installation of IBPand their vendor supplied mounting systems. Most of the testresults were within acceptable ranges established byNAVSEA. However, due to failed tests results (including 3hour gas flame and toxicity), commercial off the shelf (COTS)IBP was rejected by NAVSEA 05Z for Navy ShipboardCertification. NASA (owns a patent for a high temperatureresin) plans to fabricate IBP with their high temperature resinand then re-test for Naval Shipboard certification.

k. Shipboard Advantages of IBP Over Cable - In manyshipboard applications, especially where delivery of mediumvoltage, high current power is required, IBP offers manyadvantages over conventional medium voltage cable.Medium voltage applications, above 400 amps for the use of asingle 3-phase cable and above 1000 amps for single 1-phasecable, require paralleling multiple cables to distribute power.Restrictions in bend radii and handling of the large cable canforce a ship system designer to parallel smaller moremanageable sized cables. Paralleling cables can cause otherproblems such as the time to install medium voltagetermination kits on all of the ends of the cables. Also limitedspace inside terminal connection point boxes can necessitatean auxiliary connection box to fit the multiple connections.IBP supports modular construction of ships, where cable doesnot. Many shipbuilders are building ships in sections that areoutfitted with equipment, piping and electrical pathways whileseparated. Once fully outfitted, these sections can be fullytested electrically. If a component failure is discovered duringtesting, it is much easier to fix while the module is openended. The opened ended modules can then be broughttogether and the piping, HVAC, and electrical systems fromeach module can be connected to other modules. With IBP,

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Pwr KV Amps IBP TypeMW

1 20 3.3 4374 (3) Individual IBP at 5000amp rated for three phase

2 20 4.16 3467 (3) Individual IBP at 4000amp rated for three phase

3 20 6.6 2187 (3) Individual IBP at 2500amp rated for three phase

4 20 13.8 1060 (3) Individual IBP at 1200amp rated for three phase

these types of electrical system installations of modularconstruction are easily accomplished. Cable must be pulledafter the sections are brought together, denying theseadvantages of modular type construction to shipbuilders.Many other advantages exist and are listed in Table 5.

IBP Cable

Per phase current up to 8000 Per phase current up toamps (Approximation only)

Custom bend radii allows Large bend radii-Depends on the cablenarrow space installation circular mil. ~~~Need sophisticatedInstallation short circuit fengsystemato

secondary fault resistant prevent se tprevent secondary faultDoes not supportSupports modular ship modular shp

construction and pre-testing constructioconstruction. . ~~~~Non survivabilityGood survivability against against blast and

blast and fragmentation agmentationfragmentationVery good fire survivability Very poor fireexpected with high temp resin survivability against fireExcellent watertight integrity Subject to water treeing

Can be introduced to the Parallel cable requireswitchgear and panels with no supplementalsupplemental connections connection to

switchgear and panelsMultiple cable require

Rigid IBP needs no trays substantial trays withmany clamps

TABLE 5: IBP advantages over cable for Shipboardapplications

1. Survivability of IBP for Military Shipboard Applications -Preventing casualties of electric power distribution cable hasbeen a priority for the U.S. Navy for several years due torecent incidents involving missile, mine and sabotage strikeson Navy ships. Rubber jacketed cable offers little protectionfrom ordinance hits. Building protective steel enclosuresaround susceptible cable runs has been done in the past butat a cost of adding size, weight and expense to shipboardconstruction. Also it would be impractical to protect all areaswith these steel enclosures, leaving vulnerable gaps in theship's electrical system. Studies and testing have beenperformed on the stainless steel jacketed IBP to determine itssurvivability to ordnance hits when installed in mock-ups oftypical Navy shipboard compartments. Tests performed byNSWCCD at Aberdeen Proving Grounds in Aberdeen, MDdemonstrated that the IBP does offer significant increasedsurvivability to fragmentation hits compared to rubber-jacketedcable.

m. IBP to Improve Homeland Security - The Office ofHomeland Security has required that outdoor power utilitysub-stations be upgraded to include measures to secureagainst terrorist attacks. Several representatives from

electrical power utilities have expressed an interest in the IBPtechnology as a means of adding security to the sub-stations.Outdoor electrical sub-stations use exposed bus bars andcables to connect from transformers to switchgear equipment.A length of chain thrown over a sub-station fence could createa catastrophic failure that could destroy the entire sub-station.Replacing the exposed bus bars and cables with IBP wouldprevent such failures.

VI. PHYSICS-BASED DESIGN

Today, shipboard cable selection, procurement andinstallation are based on rule based lump sum calculation andselection, such as Mil Spec, Commercial Spec, rules andregulations. IBP will have many sizes and components tosupport voltage and ampere requirements. Theserequirements will play vital roles for modular construction andpower management as well as safety and security of theelectrical system. The IBP will require an extensive assemblyprocess and a design developmental process using modelingand simulation tools. The basic design will lead to modelingand simulation and then to prototyping, establishing physicsbased design cycle. The proven prototypes and models willbe the specifications.

VIl. FUTURE SHIPBOARD CONCEPTS FOR IBP

The ability of the IBP to transmit currents up to 8000 ampsat medium voltages and the recent development of in-linevacuum circuit breakers or circuit interrupters, can allow forre-thinking shipboard electrical distribution systems. Theability to place distribution size in-line circuit interruptersanywhere on a ship could eliminate the need forswitchboards. These circuit interrupters could easily bedesigned to accept IBP, giving a shipboard electric system anew paradigm of possible configurations. NSWCCD has beenstudying the potential shipboard use of multi-node IBPs withan in-line circuit interrupter at each node to allow rapidreconfiguration of electric power distribution either manually orthrough algorithm-based decision-making software. Rapidoptimized reconfiguration of the power system in response tocausality conditions would enable a ship to continue on itsmission after an ordinance hit. The elimination ofswitchboards would save significant weight, compartmentspace, and cost for shipboard construction and do away withthe necessity of routing all high power cabling to one area ofthe ship from which all load centers are provided power.

Vil. CONCLUSIONS and RECOMMENDATIONS

Conclusion:

1. IBP development, testing, and prototyping can result indirect substitution for shipboard electrical power cable.

2. IBP can provide modularity in shipboard powertransmission and distribution systems.

3. Future ship design may greatly benefit from the use ofIBP, contributing to significant cost, size, space, and weightreductions.

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Electrical Engineering Degree with Honors from Fort Schuyler,Maritime College, and State University of New York in 1975.Recommendations:

1. The IBP application practices in shipbuilding should beincluded in standards such as IEEE-45 and IEEE-1580.

2. IBP application practices should be included in the ABSrules for commercial ships, ABS NVR for naval vessels rules,as well as other national and international shipbuilding rulesand regulations.

3. A guide for IBP shipboard installation practices should beprepared with consultation with the shipyards having installedIBP.

4. Consult the IBP vendors to optimize IBP custom sizes,ampacity ratings, insulation rating, exterior jacket material andother options to provide the best IBP type for each shipboardapplication.

IX. ACKNOWLEDGEMENTS

The authors would like to acknowledge the contributions ofMr. Kevin Walker, P.E., NSWCCD and Mr. Donald Strawser,NAVSEA.

X. REFERENCES

1. "APODS SDC Certification Test Report" NSWCCD-98-TR-2005/25, R. Worth, J. Yan, S. Kolesar, S. Swindler, J. White2. Duresca and Tiresca technical sales brochures from Moser-Glaser Corporation3. ISOBUS technical sales brochures from Pressinger BusbarProduction, Inc.4. "CVF Project: Trip Report for Visit to Meyer Werft", E.Purves & F. Elliot, Royal Navy, November 2003.5. IEEE-45 Recommended Practice for Electrical Installationson Shipboard6. IEEE-1580 Recommended Practice for Marine Cable forUse on Shipboard and Fixed or Floating Platforms7. ABS NVR American Bureau of Shipping Naval VesselRules

Richard Worth received a B.Sc degree in ElectricalEngineering from Clarkson University in 1982. He worked asa distribution engineer at Niagara Mohawk Power Corporationin Syracuse, NY from 1982 to 1983. He then attendedClarkson University for graduate studies in electricalengineering until 1984 and then accepted an electricalengineering position with the Naval Surface Warfare Center,Carderock Division (NSWCCD) located in Annapolis, MD thatsame year. In 1998, he transferred to the NSWCCDdetachment located in Philadelphia. He hasworked in theR&D departmentfor Naval shipboard power distribution andmachinery for the past 22 years at NSWCCD. Since 2004he has been the principal investigator for the Advanced PowerDistribution Solid Design Conductor (APODS SDC) program.(The APODS SDC term is the original term used for the IBPproduct described in this paper.) He is also an IEEE andASNE member.

Charles Smith has worked for Newport News Shipbuildingfor forty-three years. Mr. Smith has a five-year apprenticeshipin Marine Engineering concentrating in Electrical Design fromthe Newport News Shipbuilding Apprentice School. He has aBachelors Degree in Management Information Science and aBachelors Degree in Accounting and Finance, both fromChristopher Newport University. Also, he has a MastersDegree in Management Engineering from George WashingtonUniversity. Mr. Smith has worked all areas of marine electricaldesign. He was a supervisor of Electrical Systems for AircraftCarrier Overhauls with responsibility for overhaul of theelectrical system and components. Mr. Smith is currentlyworking advanced technology insertion concerning the AllElectric Ship Program and Marine Integrated Power Systems.

Xi. VITA

Moni Islam has thirty-four years diversified electricalengineering experience in planning, designing, developing,and implementing new shipbuilding and ship modernizationprograms. Mr. Islam is the Chair Elect of IAS-PCIC- MarineIndustry Sub-Committee (2005- 2007), IEEE Standard 45central committee Vice-Chair and working group member ofIEEE Standard-P1662. He has been involved in "All ElectricShip" R&D programs for many years and has authored manytechnical papers on shipboard electrical power. Mr. Islam wasthe principal investigator of Ship Smart-System Design (S3D)feasibility study and principal investigator (NGSS) for ISSB(Integrated Structural Building Block), ONR funded researchprojects. Mr. Islam authored "Handbook to IEEE Standard 45,A Guide to Electrical Installation on Shipboard (August 2004Release)". Mr. Islam received his Bachelor of MarineEngineering Technology with distinction from the MerchantMarine Academy, Bangladesh in 1969, and Bachelor of

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