ALFA STANDARD brochure - CHI LI TOMAS

1 alfa ADDRESSVia Giordano Bruno, 1/3 - 24040 Arcene (BG) ITALYTel. +39 - (035) 419 3053 Fax +39 - (035) 419 3052 10/06 SummaryGeneral Characteristics1 Iso Phase Bus Technical Data2 STANDARD Technology3 Auxiliary Equipment4 Quality Control5 General CharacteristicsIso Phase Bus Technical DataStandard Technology Conductor Enclosure Supporting insulators Expansion joints Bushing insulators Flexible braids Current transformers Supporting structures Wall passage Transformer & Generator terminal casingAuxiliary Equipment Pressurization Voltage Transformer Cubicle Neutral Grounding Cubicle & Star Point Cubicle Air Forced Cooling System Hydrogen leakage monitoringQuality Control245556677788899910111112 The alfa STANDARD Isolated Phase Bus systems are continuous enclosure type , bonded at the extremitiesand usually earthed on one end as STANDARD .

2 Thisconfiguration offers more electrical advantages than the non-continuous enclosure type magnetic field produced by the conductor currentinduces in the enclosure a current, equal to about 90 -98% of the conductor current, in the opposite resulting external magnetic field is works, grated panels and rods of reinforcedconcrete are therefore not influenced by losses due tothe magnetic induction. The only remaining stresses arethose due to the zero-current component in case ofshort circuit currents. There is no problem with steelwork structures in theproximity of the continuous enclosure type IsolatedPhase Buses because significant losses and the resultantrise in temperature cannot serious problems found in using conventional barebars or cables, for the main circuit connections betweengenerator and main, auxiliary or voltage transformers, inall types of power plants (Hydroelectric, Thermoelectric, ) with high ratings of current up to 50 kA at36 kV, can be solved by the use of Isolated Phase 1967 alfa STANDARD (ISO certified 9001 & 14001)has been designing, producing and building IsolatedPhase Bus continuous enclosure type, for installationsall over the CharacteristicsGeneral Characteristicscylindrical shape, seam welded aluminiumenclosure.

3 No losses on adjacent Due to theconfiguration of this system, the induction effect ofthe currents heating and losses in the nearbycomponents such as steelwork, cables, pipes, etc. iscancelled. Personal The personnel can safely touchthe busbar enclosures because all the accessibleparts are grounded, the temperature rise is inaccordance with the standards (IEC, ANSI, CSA,etc.) and the voltage rise in the enclosure isnegligible, having a resistive origin only. No The degree of protection (IP65)afforded by AS IPB prevents pollution and foreignbodies from being deposited on the conductorsupport insulators. This removes the risks of aflashover, even in a corrosive industrialenvironment. This system is an assembly of rigid conductors,supported by porcelain or epoxy resin insulators andmounted into an earthed metal advantages of this solution are: Continuous Not possible for a phase-to-phase fault to occur.

4 Reduction of the risk of aphase to earth fault and not possible to transmitthis fault to other phases. Air insulation is the mostreliable of all dielectrics, exhibiting the highestconsistency and resistance to degeneration as wellas the property to easily re-generate itself. Simplified support Greatly reducesthe electromagnetic forces between conductors ofadjacent phases and reduces the forces in bends andother discontinuities caused by high short-circuitcurrents. Allows the possibility of large unsupportedspans because of the high moment of inertia of the32 Electromagnetic FieldConductorThe conductors are normally made of aluminium sheets(Al - ) rolled and welded to one another so as toform of a cylinder (in some cases conductor can becopper ). Aluminium extruded tube is also usedfor diameters 330 IPB STANDARD sizes carry currents up to 25kAwith natural cooling and 50kA with forced ventilationcooling.

5 For plant terminals and expansion joints (whererequired), flexible connections are provided. Whenexpansion joints are used, one of the ends of theexpansion connector is factory welded to a conductorwhile the other end is field welded to the matchingconductor. In order to increase the heat-dissipating capacity byradiation and reduce the temperature rise of the busconductors, matt black paint is used on the Phase Bus Technical Data4 Our IPB are classified into three types depending on thevoltage and current rate. Type CX for Large This is Isolated Phase Buscharacterized by the use of aluminum conductor that issupported by porcelain insulators in an enclosure that isalso made of aluminum. Air is the main insulating is used primarily in the transport of large power fromGenerator to GSU Transformer in large Thermo-electric,Nuclear and Hydro Power Plants (up to 50 kA and 36 kV).

6 Type MR for Medium This is Isolated Phase BusD1D2 IIA400400B300300150150with the same characteristics as type CX except here theinsulators may be either porcelain or resin. It is usedprimarily in the transport of power in medium sizepower plants (up to 25 kA and 36 kV). Type MP for Medium This is Isolated Phase Bus usingthe same technologies of the types CX and MR, designed tohave the most economical solution for the transport of powerin Hydroelectric, Gas Turbine and Combined Cycle PowerPlants of a smaller capacity, which adds the possibility ofhousing copper conductor (up to 10 kA and 24 kV). STANDARD TechnologyEnclosureThe enclosure is made of aluminium sheets (Al - )rolled and butt-welded to form a tubular shape. Inspection doors are provided to allow access forassembly or removal of current transformers, expansionjoints, thermometers, flexible joints and other three enclosures phases are short circuited at theends by the welding of aluminium shunts sized inaccordance with the nominal current carried.

7 One of these shunts will be grounded for the servicestaff s protection. As for the conductors, the enclosures are also matt blackpainted on the internal surface in order to increase theheat-dissipating capacity by radiation and reduce thetemperature rise of the accessible element of theIsolated Phase Bus system. Furthermore, when required by technical specification orsuggested by enviromental conditions, external surfacemay be also painted. RatedRatedIPB typeD1 (mm)D2 (mm)I (mm)A (mm)B (mm)VoltageCurrent3000A10048068023401280 4000A150540740252013406000A2006008002700 1400up to9000A3307209203060152017,5kV12000A4508 5010503450165013000A60010101210393018101 5000A700111013104230191018000A8001210141 04530201025000 ACX100013701570501021703000A100600800270 014004000A150640840282014406000A20070090 0300015009000A33085010503450165024kV1200 0A45097511753825177513000A60011101310423 0191015000A700121014104530201018000A8001 31015104830211025000A9001410161051302210 3000A1008001000330016004000A150860106034 8016606000A2009001100360017009000A330105 012504050185036kV12000A45012001400450020 0013000A600131015104830211015000A7001410 16105130221020000A8001510171054302310250 00A900161018105730241030000 ACX10001710191060302510 MPMPMRMRCXCX/MRReported values are given as a mere indication.

8 These ones could be changed according to technical and environmental specific requirementsConductor temperature rise: 65 C (149 F). Enclosure temperature rise: 40 C (104 F).567 Supporting insulatorsTo assemble the conductor inside the enclosuresupporting insulators are required. They are used forholding the conductor at a required distance fromground and to support loads due to the conductorweight and stresses due to conductor expansion andshort circuit are provided with shock absorber devices thatallow the free expansion. The insulator is fixed into abox welded to the enclosure that permits easymaintenance. alfa STANDARD uses insulators made ofporcelain or epoxy resin. The number and thearrangement depend on the operating TechnologyExpansion jointsThese components are required on conductors and onenclosures to permit expansion and contraction due totemperature changes.

9 In this case, when needed,expansion joints will be usually installed along the IPBroute; designing and engineering calculation willestablish proper location of these the ends of the Isolated Phase Bus ducts (generatoror transformers connections) non-metallic flexible jointsconnect enclosures to generator or transformer housingsto prevent vibrations being transmitted to the bus ductand to permit access to the flexible terminal connectors. When required, ( to prevent hydrogen leakage fromgenerator terminals from entering the IPB enclosure orwhen a pressurization system is used), seal-offbushings are provided at the IPB extremities. In thisway the conductors are provided at the ends with seal-off bushings or bushing insulators. A synthetic siliconerubber ring allowing the free expansion of conductorprovides sealing of these baffles.

10 Bushing insulatorsThe conductor connections to generators andtransformers are made by flexible braids to avoidtransmission of vibration onto the IPB. These also act asremovable isolation , during site installation, the use of flexiblebraids that can easily flex on all 3 axis, would enhanceeasiness of connection, even when a relatively slightdifference of alignment between IPB and machinesmight braidsCurrent transformers Ring type current transformers are mounted on a flangeinside the enclosure. Installation and removal of thesetransformers is carried out through an inspection doorsized for this secondary windings are wired out of the enclosure,via a sealed box provided with a cable inlet stuffing Technology9 PressurizationThe superior degree of protection (IP65) provided by ASIPB makes it unnecessary to provide air conditioning ofany type under normal conditions.