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Splicing theory & products
- 1. SPLICING THEORY & PRODUCTS • Supplied length is not long enough (reel end) • Length is limited due to pulling distance and bends • Cable failure • Cable damaged after installation (e.g. dig-in) • Tap into an existing cable (Tee or wye splice) CAN SAVE $ $ $ “Why Splice a Shielded Power Cable?”
- 2. cause serious injury or death. Installation should be performed by personnel familiar with good safety practice in handling high voltage electrical equipment. De-energize and ground all electrical systems before installing product. Caution: Working around energized high-voltage systems may SPLICING THEORY & PRODUCTS
- 3. DEFINITION A Splice can be defined as two or more conductors joined with a suitable connector, reinsulated, reshielded and rejacketed with compatible materials applied to a properly prepared surface.
- 4. Functions of MEDIUM VOLTAGE SPLICES • Insulate Between Voltage and Ground • Maintain Metallic Shield Continuity • Provide Protection from Impact and Moisture • Provide for a 30-40+ Year Service Life • Provide Resistance to Acidic & Alkaline Soil • Control Electrical Stress in Connector Area
- 5. Common Steps for POWER CABLE SPLICING 2. Join Conductors with a Connector 3. Reinsulate 4. Reshield 5. Rejacket 1. Properly Prepare Surface
- 7. Common Methods of SHIELDING THE CONNECTOR AREA SEMI-CON “GRADING” EXAMPLE TAPE SPLICE MOLDED SPLICE CONDUCTIVE “ELECTRODE” CAPACITIVE (HI-K) “GRADING” (“Faraday Cage” Effect) HEAT SHRINK SPLICEEXAMPLE EXAMPLE
- 8. Common Methods & Materials for RE-INSULATING EPR RUBBER SPLICING TAPE SILICONE RUBBER COLD SHRINK EPDM MOLDED PUSH-ON EVA HEAT SHRINK
- 9. Common Methods of Semi-Con RE-SHIELDING INSULATION SHIELD HEAT SHRINK SPLICE TAPE SPLICE MOLDED RUBBER SPLICE Semi-Conducting Tape Integral Molded Semi-Conducting Jacket Semi-Conducting H.S. Tube
- 10. Common Methods of Metallic RE-SHIELDING Braided Shielding Tape Shielding Sleeve (or Shielding Sock) Concentric Neutral Wires (from Original Cables) Ground Strap Jumper
- 11. Common Methods of RE-JACKETING Resin Armorcast™ Mechanical Protection Molded Semi-Conducting Rubber Rubber & Vinyl Tapes Cold Shrink Heat Shrink
- 12. GROUNDING • The shielded cable system must be grounded! • There are many engineering & safety considerations for determining where & how many times to ground. • A splice does not necessarily have to be a grounding location. • Splice manufacturers generally provide a method for grounding (for use if the splice is to be grounded). ?
- 14. Typical MOLDED RUBBER SPLICE SEMI-CONDUCTIVE ELECTRODE (Replaces Cable Strand Shielding) EPDM INSULATING RUBBER (Replaces Cable Insulation) SEMI-CONDUCTING JACKET (Replaces Cable Insulation Shield & Jacket)
- 15. Examples of PUSH-ON MOLDED SPLICES Elastimold PCJ Cooper EZ II 3M QS-II
- 16. 3M™ QS- II APPLICATIONS JACKETED CONCENTRIC NEUTRAL CABLES Without Splice Jacketing Cold Shrink Jacket Heat Shrink Jacket
- 17. Comparison to PUSH-ON “REPAIR SPLICE” Standard 3M™ QS-II Splice Kit (For repairing damaged cable with 1 elongated splice, eliminating the need for 2 standard splices) 3M QS-II Cable Repair Splice Kit
- 18. + Less Installation Time than Tape Splice + Production Tested Splice Body - Installation Force to Push on Splice - Parking Position on Prepared Cable (Non-symmetrical cutbacks) - Limited Application Range - Special Connector Required - EPDM - Rigid in Cold Weather - Must Know Cable Details PUSH-ON EPDM RUBBER SPLICE
- 20. Typical HEAT SHRINK SPLICE Stress Relief Material Sealant Splice Tube Insulation & Insulation Shield Semi-con
- 21. Example of HEAT SHRINK SPLICE Raychem HVS
- 22. Step 1 Step 2 Step 3 Step 4 Heat Shrink Splice INSTALLATION Park Tubes on Cable Connect Stress Relief Material Stress Relief Material
- 23. Step 5 Step 6 Step 7 Step 8 Black Stress Control Tube Red Insulating Tube Red Sealant Black/red Dual Layer Tube
- 24. Step 9 Step 10 Step 11 Completed Splice Ground Braid Shielding Mesh Rejacketing Tube
- 25. HEAT SHRINK SPLICE + Less Installation Effort and Time than Tape Splice + Wide Application Range (Easy Size Transitions) + Symmetrical Cutbacks - Parking Position on Cable Jacket - Torch Required (Permit required or Torch not allowed) - Applying Heat Properly - Must Know Cable Details Note: This is not a 3M product
- 27. Typical COLD SHRINK SPLICE SEMI-CONDUCTIVE ELECTRODE (Replaces Cable Strand Shielding) SILICONE INSULATING RUBBER (Replaces Cable Insulation) SEMI-CONDUCTING INSULATION SHIELD (Replaces Cable Insulation Shield)
- 28. Example of Cold Shrink “EPDM RUBBER” Splice Pirelli Elaspeed Installed Cold Shrink Spiral Core Jacket Pull Straps Cut & Remove Straps
- 29. Cold Shrink “EPDM RUBBER” Splice + Less Installation Effort + Wide Application Range (Easy Size Transitions) + Symmetrical Cutbacks + Constant Pressure on cables/connector - Parking Position on Cable Jacket - EPDM does not shrink well in Cold Weather - Possibility for Core Hang-up - Must Know Cable Details Note: This is not a 3M product
- 30. Example of Cold Shrink “SILICONE RUBBER” Splice 3M™ QS-III Cold Shrink Cable Splice Installed (With Cold Shrink Jacketing)
- 31. Cold Shrink Silicone Rubber Splice INSTALLATION Step 1 Step 1 Continued) Step 2 Steps 3 & 4 Park Jacketing Tube(s) Park Splice Body Connect Apply Red Compound
- 32. Step 5 Step 6 Step 7 Step 8 Install Splice Body Connect Neutrals (not shown) (Shield Sleeve for shielded cable Shown) Rubber Mastic Position Jacketing Tube
- 33. Step 9 Completed Splice Install Jacketing Tube
- 34. + Less Installation Effort + Wide Application Range (Easy Size Transitions) Cold Shrink “SILICONE RUBBER” Splice + Symmetrical Cutbacks + Constant Pressure on cables/connector + Silicone Material shrinks well in all weather and is flexible + Production Tested Splice Body - Parking Position on Cable Jacket - Possibility for Core Hang-up - Must Know Cable Details Note: This is a 3M product
- 35. Cold Shrink 3M™ QS-III Cold Shrink Cable Splice Cold Shrink Splice Body Cold Shrink Jacket INTRODUCING
- 36. 3M™ QS-III Cold Shrink Cable Splice “FEATURES” • COLD SHRINK DESIGN - Constant pressure on cables/connector – Good seal between cable and splice – Higher impulse Voltage levels – Lower interface electrical stress • SILICONE RUBBER MATERIAL – Good cold weather application – High temperature rating (class H) – Flexible splice body - moves with cable • SPECIAL ELECTRODE DESIGN - Minimizes electrical stress – Undercut electrode end – Patented electrode places higher stresses within splice insulation, not along cable interface
- 37. 3M™ QS-III Cold Shrink Cable Splice “ADVANTAGES” • No special tools (easier installation) • Minimized workmanship (faster installation) • Factory tested (reliability) • Quick installation (lower installed cost) • Safe (no gas, open flame, etc.)
- 38. 3M™ QS-III Cold Shrink Cable Splice SUMMARY THIS NEW GENERATION OF POLYMERIC SPLICES TAKES ADVANTAGE OF: • New Developments in Silicone Rubber Technology • Integrated 1-piece Design • Factory Made - Factory Tested, Reliability • Cold Shrink Design for Easier Field Installation
- 39. SPLICING SUMMARY • A “splice” may be considered as the reconstruction of a short section of cable - For proper splice selection, “match the cable”! • Good cable preparation is critical for a reliable splice installation ! • For most installations where the cable details are known, modern molded and shrink type splices may be used for reliability, simplicity andfast installation.
- 40. SPLICE WORKSHOP Examine and Discuss Splice Samples
Notes de l'éditeur
- TITLE SLIDE Unlike terminations, (which are needed to terminate the ends of every shielded cable run), splices are not necessarily required for a cable installation. Whenever possible, splicing is normally avoided. However splicing is often an economic necessity. There can be many reasons for constructing or installing a splice. For splice selection (voltage rating, conductor size, shielding type, etc.): “MATCH THE CABLE”
- DEFINITION OF A SPLICE In addition to this textbook definition, splices are often referred to as “rebuilding the cable,” or “building a short section of cable,” where all of the cables layered functions are reproduced using various methods and materials.
- LIST OF MEDIUM VOLTAGE SPLICE FUNCTIONS These functions provide for the electrical integrity of the cable and splice system, plus providing sealing, mechanical protection and longevity for splice field applications such as immersion in manholes, direct burial, aerial installations, etc.
- LIST OF COMMON SPLICING STEPS Emphasis is on the importance of the first step, “properly prepare surface.” Good cable preparation is critical for a quality splice installation. All of the cable layers or functions are dealt with, starting with a connector to rebuild the cable conductor; then shielding the connector to replace the cable strand shield; insulating the connection to replace the cable insulation; shielding with semi-con and metallic layers (including a ground jumper or bonding wire) to rebuild the cable insulation shield; and finally rejacketing the splice to replace the cable jacket or sheath for moisture and mechanical protection.
- COMMON SPLICING METHODS These are basic splicing methods. In actual splice applications, technologies are often mixed to optimize a splice design. For example a molded rubber splice may use a cold shrink tube for rejacketing; or an armored cable splice may use cold shrink for phase insulation and resin for re-armoring; etc.
- SHIELDING THE CONNECTOR AREA The pictures illustrate 3 common methods of shielding the connector area (replacing the cable strand shield). (Top) The tape splice simply uses semi-conducting tape to replace the cable semi-con layer. The smooth taping job shields the voids among the conductor strands and electrically grades the profile of the crimped connector. (Center) The capacitive grading uses a high dielectric constant (high-K) material to distribute the electrical field and reduce the electrical stress in the connector area (capacitive stress control is explained in more detail in the “Termination Theory” presentation). (Bottom) The conductive electrode acts as a “Faraday Cage” to smoothly distribute the electrical field over the connector area. The electrode must be in contact with the energized connector to serve this function. This places the shield around the air cavity, so that the air is not in the electrical field and therefore not electrically stressed. To accommodate this, specific connectors are usually specified for molded rubber push-on type splices.
- METHODS FOR REINSULATING THE SPLICE To perform the cable insulation function of “containing the voltage,” several different methods and materials are commonly used. Some methods are more versatile (e.g. tape method) Some methods allow for factory production testing to assure reliability (e.g. molded rubber splices, per IEEE Std. 404) Some are faster in install (e.g. cold shrink method) Some require special tools (e.g. heat shrink method)
- SEMI-CON SHIELDING The cable semi-con insulation shield can be replaced with various methods and materials: Semi-conducting tape should be smoothly half-lapped over the splice insulation. Heat shrink should be evenly heated and applied smoothly. Start shrinking in center and move out towards ends to prevent trapping air (bubble). Molded rubber splices have a built-in (integrated) semi-con jacket that is factory applied. No special installation procedures are necessary.
- METALLIC SHIELDING The metallic shielding continues the current carrying component of the cable shield across the splice. This can consist of: Electrostatic shielding (as shown with the braided shielding tape) This is not designed to carry shield currents, and must be used in conjunction with a jumper. Jumper or bonding conductor (as shown with the ground strap jumper and concentric neutral wires) It must have an ampacity rating equal to that of the cable shield. Both (for example, as used in a normal tape splice construction - not shown) The shielding sleeve combines both the electrostatic and jumper functions in a single component.. NOTE: All splice designs should contain a jumper to carry any shield currents from one cable to the other. (Whether or not the splice is actually grounded at a particular location is an engineering consideration. However, the splice should provide for the possibility of such ground connection.)
- RE-JACKETING The splice jacket continues the mechanical protection and moisture barrier of the cable jacket. In some splice designs, such as molded rubber splices, the outer layer is a jacket that serves as both the protective covering and the semi-conductive component of the insulation shield system. This is known as a semi-conductive jacket.
- SPLICE GROUNDING This visual discusses splice “grounding”: Should the shielded cable system be grounded at this splice location? ...or not? If yes, the splice should provide a method for grounding the cable/splice metallic shielding to a system ground point. Generally if no grounding specifications are available, it is common practice for a contractor to ground every splice (and termination). For splices, this is typically done in manholes, vaults, etc. When specifications are used, there may be good technical reasons for not grounding at certain locations (e.g. for single-point grounding). For jacketed direct-burial systems (e.g. jacketed concentric neutral cables), there is a RUS (Rural Utilities Service) specification for grounding the primary neutral at least every 1329 ft. (1/4 mile). (Reference: RUS Bulletin 83-1) There are special grounding kits available to accommodate this (e.g. 3M 2252 Grounding Kit)
- PUSH-ON SPLICE INSTALLATION The photo shows a molded rubber splice (sometimes referred as a pre-molded splice) being pushed over prepared cables. The splice will be centered over the crimped connector. This type of splice usually requires a special connector, so that proper contact is made with the splice inner electrode.
- CUTAWAY DRAWING OF A “MOLDED RUBBER” SPLICE This cutaway drawing of a typical molded rubber splice reveals the integrated components of the design (electrode, insulation and jacket). Note how the semi-conductive electrode makes contact with the connector; how its ends have a radius to reduce electrical stress at the cable interface; and how the outer semi-con jacket forms a stress cone at the ends of the cable semi-con.
- EXAMPLES OF PUSH-ON MOLDED SPLICES These three splices all install and work in a similar manner. The Cooper EZ II is the newest of them. Some installers like the unique molded shape because it is easy to grasp while pushing the splice onto the cables. The 3M QS-II has a very good “track record,” dating back to its product release in 1980. The performance of this splice was used as an example for the development of the original IEEE 404 “production testing” (100% factory testing).
- EXAMPLES OF JACKETING A JCN SPLICE The photo shows the same type of molded push-on splice (3M 5411 QS-II) on JCN cable, with and without jacketing. Two common methods of jacketing such an application are with cold shrink (3M SJ-1A) or heat shrink (3M HSJ-1) products, as shown.
- REPAIR SPLICE The repair splice is a specially elongated molded rubber splice designed to repair damaged cable. It uses a special “long” connector to replace the damaged conductor. This splice/connector combination eliminates the need to splice in a new section of cable with two separate splices.
- ADVANTAGES AND DISADVANTAGES This visual lists the good points of a typical push-on rubber splice (red +s), and the disadvantages (blue –s).
- HEAT SHRINK SPLICE INSTALLATION The photo shows the installation of the rejacketing tube, the final layer of this heat shrink splice. Note the heat shrink torch producing the recommended “bushy” flame.
- CUTAWAY DRAWING OF A HEAT SHRINK SPLICE This cutaway drawing of a typical heat shrink splice reveals the layered components of the design. Note that instead of semi-conductive rubber, the connector and semi-con cutbacks are shielded with a stress relief material. This particular design utilizes a splice tube (co-extruded heat shrink tube) that combines the splice insulation and insulation shield functions in a single tube. Also note that a hot-melt sealant is used for the jacket sealing.
- MAIN COMPONENTS OF A HEAT SHRINK SPLICE Stress relief material Black rejacketing tube Black/red dual wall tube Red insulating tube Black stress control tube
- PRIMARY INSTALLATION STEPS For a Heat Shrink Splice
- PRIMARY INSTALLATION STEPS (Continued)
- PRIMARY INSTALLATION STEPS (Continued)
- ADVANTAGES AND DISADVANTAGES This visual lists the good points of a typical heat shrink splice (red +s), and the disadvantages (blue –s).
- COLD SHRINK SPLICE INSTALLATION Photo shows installation of the cold shrink jacket, the final layer of this splice.
- CUTAWAY DRAWING OF “COLD SHRINK” MOLDED SPLICE This cutaway drawing of a typical “cold shrink” molded rubber splice reveals the integrated components of the design (electrode, insulation and insulation shield). Note how the electrode varies from that of a molded push-on splice: The shrink characteristics of the design causes the electrode to shrink tightly against both the cable and connector, without the large air cavity of a typical push-on design. This makes the “cold shrink” design much less connector sensitive, and it can normally be used with standard compression connectors.
- PIRELLI ELASPEED SPLICE Photos show before and after installation. The jacket pull straps can be difficult to use under field conditions.
- ADVANTAGES AND DISADVANTAGES This visual lists the good points of a Cold Shrink EPDM rubber splice (red +s), and the disadvantages (blue –s).
- 3M QUICK SPLICE III Photos show before and after installation. Note that both the splice and jacket are cold shrink applied (no pull tabs or pull straps are necessary).
- PRIMARY INSTALLATION STEPS Cold Shrink Silicone Rubber Splice
- PRIMARY INSTALLATION STEPS (Continued)
- PRIMARY INSTALLATION STEPS (Continued)
- ADVANTAGES AND DISADVANTAGES This visual lists the good points of a Cold Shrink silicone rubber splice (red +s), and the disadvantages (blue –s).
- INTRODUCTION OF THE 3M QS-III Photos show “cold shrink” installations of both the splice body and the outer jacket.
- LIST OF QS-III FEATURES Cold Shrink Design - 3M invented “cold shrink” technology. Over 30 years of experience has resulted in numerous design improvements. Silicone Rubber Material – As a cold shrink splice material, silicone rubber is unique to 3M. During the development stages it proved to have several key advantages over EPDM (e.g. better cold weather performance, better heat resistance qualities, better ability to maintain conductivity through stretched-to-shrunk transition, etc.) Special Electrode Design – This patented design feature controls the stress in the critical area at the end of the splice electrode. The result is reduced electrical stress along the cable/splice interface for a more reliable splice.
- LIST OF QS-III ADVANTAGES These “advantages” can be linked to the aforementioned “features” to reveal a FAB (features, advantages, benefits) for the QS-III Splice.
- SUMMARY OF QS-III
- OVERALL PRESENTATION SUMMARY
- REVIEW SPLICE SAMPLES (Provided by 3M Representative)