HIGH VOLTAGE CABLE ACCESSORIES - Application, Design, Installation, Testing - Ivan Jovanovic G&W Electric Company 1
Year 1905 First detachable porcelain pothead for 4 kv systems
Year 2015 Terminations and joints from 5kV up to 345 kv for all cable types
Chicago Toronto San Luis Potosi Delhi Shanghai Salvador
Application of Underground Cables Any sections of Transmission and Distribution lines may be underground
Examples of cable installation Directly buried or in conduits in trenches
Laid on trays in tunnels Examples of cable installation
Examples of cable installation Laid on trays under bridges
Examples of cable installation Laid on sea floor or river bed Submarine cables
Cable accessories Outdoor termination Equipment mount termination HV Power Cable Joint
Distribution of electrical stress in Conductor screen power cable 2 V Einsscr. = ODins ODins ln ODcondscr. Insulation screen
Cable end in accessory how does it work? High stress at conductor High stress at insulation screen Stress evenly distributed Cable conductor Cable insulation Cable insulation screen Cable conductor Cable insulation Cable conductor Cable insulation Stress cone insulation Stress cone ground electrode Edge of cable insulation screen Cable End without Insulation screen stripped back Cable End with Insulation screen stripped back Cable End inside termination
Extruded Cable Conductor Screen Insulation Screen Metallic Sheath Screen Wires Jacket
OUTDOOR TERMINATIONS GIS & Oil Immersed TERMINATIONS JOINTS
Use of outdoor terminations Cable terminations connects power cable to other electrical components: Overhead lines Station buses
Structure-mount outdoor terminations in substation Termination
Pole mount outdoor terminations on transmission line pole Termination
Typical design of outdoor termination
Distribution of electrical stress in the critical areas Outdoor Termination Deflector radius Interface between stress cone and cable insulation Deflector angle
Silicone Rubber Stress Cone Insulating Rubber Oil seal Sleeve Conductive Rubber (Deflector)
Use of equipment mount cable termination GIS cable termination connects the cable to the gas insulated switchgear (GIS) Oil-immersed termination connects the cable to power transformer
GIS Housing GIS Termination GIS terminations GIS terminations
Typical design of dry type GIS termination Contact pad Corona shield Connector Epoxy insulator Stress cone GIS interface plate Clamping ring Compression spring assembly Cable Entrance housing Cable support
Design considerations
Per international and domestic standards it is required that terminations and GIS gear are interchangeable regardless of who made them. G&W GIS terminations meet that requirement.
Joint Design - General Joint outer screen Shield Break Cable semi-con screen HV electrode Ground electrode (deflector)
Electrical stress inside the joint Design - Electrical
Design - Electrical Magnitude of electrical stress in the critical areas Corona shield Deflector top Deflector angle
Use of Joint in Cable Bonding Cable bonding functions: Limit cable metallic screen voltages Reduce or eliminate the screen losses Maintain a continuous ground path to permit fault-current return and adequate lightning and switching surge protection.
Multiple Point Bonding Induced current in screen Load current Cable metallic screen Lower load rating of cable system Zero voltage at both cable ends (no safety hazard)
Single Point Bonding Induced Voltage in screen Voltage at open end (In US 100-200V Max) Cable length Induced voltage at open cable end (safety hazard) Higher load rating of cable system
Cross Bonding use of shield break joints Location of shield-break joints No induced voltage at open cable end (no safety hazard) Higher load rating of cable system
Paper Cables PIPE OIL or GAS PAPER CABLES
OUTDOOR TERMINATIONS EQUIPMENT TERMINATIONS Straight Joints
Stress in paper cables x y g Cable conductor Cable insulation Dc Di Joint insulation Stress cone (L-L profile) Formula for axial component of electrical field at the stress cone g = E x Ln Ln Ln y Dc 2 Di Dc
Oil-impregnated paper cable Relevant for connector design Relevant for Stress cone design
Retrofit of the old termination with new one
HV Transition Joints Definition: Device for connecting HV oilimpregnated paper cable to solid dielectric cable Typical application: To expand existing UG transmission network To replace ailing section of old oilimpregnated paper cable with new extruded cable
HV Transition Joints Relatively small usage, expected to grow significantly Up to 161 kv class, many different designs in operation At 230 kv most designs are back-toback Limited use and availability at 345 kv High pressure vs. Low pressure (in regard to insulating fluid at paper cable side)
Back-to-Back with two Insulators (CIGRE TB 415) Equipment type termination for extruded cable Equipment type termination for paper cable Gas or liquid Housing Extruded cable Paper cable Connector Corona shields
Back-to-Back with one Insulator Stress cone Gas or insulating liquid GIS or Transformer type termination Extruded cable Paper cable Conductor Seal Corona shield Connector Housing
Composite design Stress cone Epoxy insulator with built-in HV electrode Paper cable stress cone Extruded cable Paper cable Springs Connector Housing Gas or liquid
Single-core Transition Joint for SCFF Cable Back-to-Back with One Insulator Extruded cable Stainless steel housing Stress cone (paper roll) Tinned Cu housing Dry-Type Termination Connector clamp Paper cable Insulating fluid
Stress cone installation with perforated Paper Roll Paper roll (stress cone) Stress cone slope Paper is torn along factory cut perforations
Finalizing the stress cone Copper band Copper mesh is applied over the slope
Field Installation Final installation step: Oil filling of the single core 138 kv LPOF to XLPE transition joints in the field
Three-core Transition Joint Telescoping housing suitable for short manholes Dry-type GIS terminations 3-C Paper cable Oil breach assembly Spider assembly reinforced to prevent TMB Paper roll and crepe paper tape build-up
Installation of 3/C Transition Joint Bushing of the drytype termination
Design Tests per IEEE 404 138 kv HPFF Transition Joint Extruded cable in conduit HPFF transition joint Number of samples: 2 AC voltage: 1min and 24h Impulse voltage Ionization factor Load Cycling Pipe-type cable Accumulator HPFF transition joint Extruded cable
Installation of Cable Accessories
Excerpt from International study on worldwide usage of HV cable systems (CIGRE TB 177, Section 3 Worldwide Usage of Accessories for HV Extruded Cables, Page 29) The assembly of the accessories is the most vulnerable part of a project involving the manufacture and installation of a new cable circuit.
Parts Heat shrinkable tubing B/M and installation instructions Joint body expended onto spiral core tube Self-fusing insulating tape Semi-con tape, 25mm wide Semi-con tape, 50 mm wide PVC tape Sand paper #150 to #600 grit Self-fusing Aqua-Seal tape Tinned Cu grounding mesh Connector Hot-melt tape #18AWG Cu wire String solder Gloves
Installation Steps 1. Cable preparation / Preparacion del cable 2. Connector crimp / Ponchado del conector 3. Connector tape fill / Encintado con cinta semicontora sobre el conector 4. Shrinking of the joint body / Contraccion del empalme 5. Taping and grounding / Encintado y Aterrizado 6. Outer joint protection / Colocacion de la manga termocontractil y (si es necesario) la cubierta de cobre
Cable preparation Prepare cable ends per installation instructions / Preparacion del cable de acuerdo a instruccines de instalacion
Connector crimp Slide the connector onto cable conductor
Connector crimp Butt the conductors into the connector
Connector crimp
Connector crimp
Shrinking of the joint body Clean cable insulation and apply grease
Shrinking of the joint body Position the joint and start pulling the cord
Shrinking of the joint body
Shrinking of the joint body Check the position of the joint relative to the positioning marks
Taping and grounding Apply semi-con tape and insulating tapes over the joint per instructions
Taping and grounding Apply copper mesh over the semi-con tape and solder to cable metallic sheath
Outer joint protection Heat shrink tube Copper housing and / or fiberglass coffin are optional
Outer joint protection Position heat shrink tube over the joint
Outer joint protection Apply heat uniformly to shrink down the tube
Mechanical Shrink Installation Method for Stress Cones and Joints Main drivers: for Extruded Cables Minimizes chances for field errors and damage Reduces required space, installation time and cost
Mechanical Shrink Installation Method for Stress Cones and Joints for Extruded Cables Scone sliding.avi GW Mechanical Shrink Accessories-live demonstration.mpg
SLIP- ON Cable prep: Accommodates for slip on the parking side, requires rejacketing MECHANICAL SHRINK Typically no need for additional rejacketing
SLIP- ON Parking: Joint body is pushed onto the cable; requires special tool and extra time and space MECHANICAL SHRINK Joint body is parked onto the cable, no tool required
SLIP- ON Final positioning: Joint body is pushed back the cable; requires special tool, creates mechanical stress MECHANICAL SHRINK Joint body is positioned and cord is removed, no tool is required
SLIP- ON MECHANICAL SHRINK
Process and Tooling design Molding process Parameters Flow rate Temperature Pressure Molding process Variations Material (properties, quality issues) Operators (degree of process automation, skill set, training) Equipment variations Need to build process robust enough to compensate for the variations
Comparison of Different Specifications for Cable Accessories and Cable Systems
Cable, Accessory & System Standards Governing Body ICEA IEC IEC AEIC IEEE IEEE Standard ICEA S-108-720 Standard for Extruded Insulation Power Cables Rated Above 46 through 345 kv IEC 60840 Power cables with extruded insulation and their accessories for rated voltages above 30 kv (U m = 36 kv) up to 150 kv (U m = 170 kv) - Test methods and requirements IEC 62067 Power cables with extruded insulation and their accessories for rated voltages above 150 kv (U m = 170 kv) up to 500 kv (U m = 550 kv) Test methods and requirements AEIC CS9 Specification for Extruded Insulation Power Cables and Their Accessories Rated Above 46kV through 345 kv AC IEEE 48 IEEE Standard for Test Procedures and Requirements for Alternating-Current Cable Terminations Used on Shielded Cables Having Laminated Insulation Rated 2.5 kv through 765 kv or Extruded Insulation Rated 2.5 kv through 500 kv IEEE 404 IEEE Standard for Extruded and Laminated Dielectric Shielded Cable Joints Rated 2.5 kv to 500 kv Current Edition 2012 2011 2011 2006 / (2013) 2009 2012
Tests Requirements for Individual Components IEC 60840, Section for cables IEC 60840, Section for cable accessories ICEA S-108-720 for cables IEEE 48 (US accessory makers and users) for terminations IEEE 404 (US accessory makers and users) for Joints Tests Requirements for System IEC 60840 (International) section for cable systems IEC 62067 (International) section for cable systems AEIC CS9 (US utilities) for cable systems
Definitions Design Test Used in IEEE 48 and 404 to describe test sequences to qualify termination or joint for use on any cable with same or lower size / stress level. Equivalent to Type tests in IEC. Type Test Used in IEC standards for a component test (cable, termination or joint) or cable system test in order to qualify component or a system. Qualification Test on Complete Cable System Used in AEIC specification to describe a Type Test (as described in IEC). Prequalification Test Used in IEC and AEIC standards for a long term cable system test including different installation conditions (flexible and rigid, direct burial, tunnel and conduit) to demonstrate performance of a system.
Industry Standards New Developments in IEEE IEEE 48 Standard for Test Procedures and Requirements for AC Cable Terminations Used on Shielded Cables Having Laminated Insulation Rated 2.5 kv through 765 kv or Extruded Insulation Rated 2.5 kv through 500 kv Rev 2009 IEEE 404 Standard for Extruded and Laminated Dielectric Shielded Cable Joints Rated 2.5 kv to 500 kv Rev 2012 IEEE 48 and 404 will be combined: IEEE 48/404 for Distribution (up to 46 kv) IEEE 48/404 for Transmission (69 kv and up)
Industry Standards New Developments in IEEE New split combines accessories, splits voltage levels: Combine Terminations and Joints into one document Split Distribution and Transmission Two new IEEE standards Two new DGs were approved; First session @ ICC Fall meeting 2015
Design and Type tests
LOOP #1 Initial tests per IEEE 48 (terminations) Very tough requirements, up to 4Uo LOOP #2 Type tests per IEC (system test) Type tests per AEIC (system test) Type test per ICEA (cables) Remaining type El. tests per IEEE 48 El. Type test per IEEE 404 (joints) - Outdoor with composite insulator - Outdoor with porcelain insulator - Two Oil filled GIS - Two Dry Type GIS - Two Cable types The same loop plus four joints: Two without shield break in water Two with shield break in air Total ten accessories, two cable types
IEEE 48 and 404 Test Loop
G&W HV Lab
G&W HV Lab
PQ test field
Conclusions HV Cable Accessories Terminations and Joints are the critical link in any modern cable system There are many different designs that can work with any modern cable designs that follow latest cable standards Oil-filled cables (OF) are still dominant technology that has been field proven over the years Transition joints are becoming increasingly important as new solid dielectric cables are being utilized Installation of is tying together cables and accessories and highly qualified jointers are a must! New developments in standardization are critical for further successful applications of cables and their accessories