specified installation radii must be observed.G.Cable Laying -There are 4 types of cable pulling that may be done during cable laying, which are namely, nose pulling, bond pulling, driven rollers and caterpillar machines .Nose Pulling-This is done with the help of a power winch situated at the end of the trenchwhere in one end is attached to a steel rope attached to a winch. When the rope is drawn back the cable is pulled in to the trenchBond Pulling-Similar to Nose pulling However , a bond wire is involved that is tied althroughout the length of the cable and is run out through the whole trench over cable rollers and attached to a power winch. At each change in direction, a snatch block is placedto help take on the force of the pull and help guide the cable.Driven rollers-This method comprises of power rollers situated at every 10 – 20m along the trenchand pulls the cable by rolling the cable to every next unit like a conveyor belt of sorts.Caterpillar Machines -Similar to driven rollers however their whole surface area is in contact with the cableH.Jointing-Jointing operations ,instead of hours would take days or even weeks if the job is complex due to its necessity of having a clean and humidity controlled environment.I.Site TestsPE4| Christian L. Ranada
UNIVERSITY OF SANTO TOMASFACULTY OF ENGINEERINGEspaña, Manila-After every installation, tests are madeto ensure the integrity of the cable and assure that it is working perfectly. Tests such as High voltage dctests are made on fluid filled cablesX.Thermo-Mechanical Design-Variations in temperature of cables may result in thermal expansion or contraction of components so studying the effects that temperature may bring on metal components of components must be observed and taken note of.A.Buried Cables-In a well compacted backfill, The movement of the complete cable is neglected , However the longitudinal displacement of the conductor and insulation within the sheath must be considered. This movement is resisted by friction in between the core and sheath but this can be eliminated if the conductor is firmly held at both ends. -During loding cycles, aforces generated in a cable exhibit compressive forcesat high temperatures. At low temperatures it exhibits tensile forces. For a polymeric insulated cable, as the temperature increases the force developedin the conductor also increases at the same time the ability to withstand pressure decreases.B.Cables Installed in Air-There are two system that cables installed in air may apply, A rigid system which does not permit longitudinal and later movement when supporting cables, A Flexible system on the on the other hand permits lateral expansion but is controlled. Systems that allow vertical movement usually have widely spaced supports with sagged cables in between.