The cable’s two shielding systems (strand shield and insulation shield system) must be rebuilt when constructing a splice. The same two methods are used as outlined in the reinsulation process: tape and molded rubber. For a tape splice, the cable strand shielding is replaced by a semicon- ductive tape. This tape is wrapped over the connector area to smooth the crimp indents and connector edges. The insulation shielding system is replaced by a combination of tapes. Semi-con is replaced with the same semi-conducting tape used to replace the strand shield. The cable’s metallic shield is generally replaced with a flexible woven mesh of tin plated copper braid. This braid is for electrostatic shielding only, and not designed to carry shield currents. For conducting shield currents, a jumper braid is installed to connect the cables metallic shields. This jumper must have an ampacity rating equal to that of the cables’ shields. For a Cold Shrink TM or rubber molded splice, conductive rubber is used to replace the cable’s strand shielding and the semi-conductive portion of the insulation shield system. Again, the metallic shield portion must be jumpered with a metallic component of equal ampacity. A desirable design parameter of a molded rubber splice is that it be installable without special installation tools. To accomplish this, very short electrical interfaces are required. These interfaces are attained through proper design shapes of the conductive rubber electrodes. SPLICING 33 36 37 38 39 35 34
10 Laboratory field plotting techniques show that the optimum design can be obtained using a combination of logarithmic and radial shapes. 5. Rejacket. Rejacketing is accomplished in a tape splice by using a combination of the rubber splicing tape overwrapped with a vinyl tape. In molded rubber splice, rejacketing is accomplished by proper design of the outer semi-conductive rubber, effectively resulting in a semi-conductive jacket. When a molded rubber splice is used on internally shielded cable (such as tape shield, drain wire shield or UniShield® cables), a shield adapter is used to seal the opening that results between the splice and cable jacket. As a general summary, for the versatility to handle practically any splicing emergency, or for those situations where only a few splices need to be made, or when little detail is known about the cable, the most effective splice is made with tape or a tape kit. For those times when cable size, insulation diameter and shielding type are known and when numerous splices will be made, use molded rubber splices for dependability and simplicity as well as quick application. (Reference: IEEE Std 48-1975. Quoted with permission as follows:) “This standard supersedes IEEE Std 48-1962 Standard for Potheads. (Note: Current standard is IEEE Std. 48-1990) “The superseded document encompassed only the pothead, a cable termination designed primarily for cables having laminated insula- tion, and which sealed the end of a cable and provided insulation egress for the conductor or conductors.
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- Spring '20
- Sir Choi
- power cable, electrical products division