IOCL Junior Operator MCQ Part-8 || IOCL Junior Operator General Science Questions and Answers31. Why are paper-insulated cables always provided with a protective covering?1 . To prevent moisture absorption 2 . To increase flexibility 3 . To improve conductivity. 4 . To enhance mechanical strength Answer and SolutionAnswer: "To prevent moisture absorption "The protective covering, such as a metallic sheath, is essential to prevent moisture from degrading the paper insulation. Discuss32. What is done to the ends of paper-insulated cables left unused on site during laying?1 . They are left open to dry 2 . They are temporarily covered with wax or tar 3 . They are wrapped in plastic 4 . They are connected to a grounding rod Answer and SolutionAnswer: "They are temporarily covered with wax or tar "Wax or tar is used to create a temporary seal, preventing moisture from entering the cable ends. Discuss33. In what type of cable routes are paper-insulated cables most profitably used?1 . Routes with few joints 2 . Low-voltage distribution 3 . Congested areas 4 . All of the above Answer and SolutionAnswer: "All of the above "Paper cables are best suited for long, continuous runs, Low-voltage distribution and Congested areas with minimal joints to reduce the risk of moisture ingress at joint locations. Discuss34. What is the base material used in varnished cambric insulation?1 . Synthetic polymers 2 . Cotton cloth 3 . Vulcanized rubber 4 . Impregnated paper Answer and SolutionAnswer: "Cotton cloth "Varnished cambric uses cotton cloth as its base, which is then treated to enhance its insulating properties. Discuss35. What is the purpose of coating the varnished cambric with petroleum jelly compound?1 . To increase its dielectric strength 2 . To prevent moisture absorption 3 . To improve its conductivity 4 . To allow for sliding of turns as the cable is bent Answer and SolutionAnswer: "To allow for sliding of turns as the cable is bent "The petroleum jelly acts as a lubricant, enabling the layers of cambric tape to move against each other without damage when the cable is flexed. Discuss36. What is the approximate dielectric strength of varnished cambric insulation?1 . 4 KV/mm 2 . 1 KV/mm. 3 . 2 KV/mm 4 . 10 KV/mm Answer and SolutionAnswer: "4 KV/mm " The dielectric strength of varnished cambric insulation is 4 KV/mm. The dielectric strength of 4 KV/mm indicates the maximum electric field the insulation can withstand before electrical breakdown occurs. Discuss37. What is the range of relative permittivity for varnished cambric insulation?1 . 1 to 2 2 . 2.5 to 3.8 3 . 5 to 6 4 . 10 to 12 Answer and SolutionAnswer: "2.5 to 3.8 " The range of relative permittivity for varnished cambric insulation is 2.5 to 3.8. Relative permittivity (dielectric constant) in this range signifies the material’s ability to store electrical energy in an electric field. Discuss38. What is the primary process used to produce Polyvinyl chloride (PVC)?1 . Polymerization of acetylene 2 . Impregnation of paper 3 . Extrusion of natural resins 4 . Vulcanization of rubber Answer and SolutionAnswer: "Polymerization of acetylene "PVC is a synthetic polymer created by linking acetylene molecules together in a process called polymerization. Discuss39. In what form is raw PVC obtained before it is used for cable insulation?1 . To increase conductivity 2 . To improve dielectric strength 3 . To make PVC flexible and pliable 4 . To reduce cost Answer and SolutionAnswer: "To make PVC flexible and pliable "Plasticizers are high-boiling-point liquids that are mixed with PVC to make it more flexible and less brittle, which is essential for cable insulation. Discuss40. What is a significant advantage of PVC insulation regarding its electrical properties?1 . Low conductivity 2 . High insulation resistance 3 . Low capacitance 4 . Low dielectric loss Answer and SolutionAnswer: "High insulation resistance " A significant advantage of PVC insulation regarding its electrical properties is its high insulation resistance. This means PVC is very effective at preventing the flow of electrical current through it, which is crucial for safety and efficiency in electrical applications. Discuss123456789
