Class 11 Power Chapter 4 Installation of Cables

Class 11 Power Chapter 4 Installation of Cables Solutions English Medium As Per AHSEC New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters Class 11 Power Chapter 4 Installation of Cables Question Answer and select need one. Class 11 Power Chapter 4 Installation of Cables Notes Download PDF. AHSEC Class 11 Elective Power Question Answer English Medium.

Class 11 Power Chapter 4 Installation of Cables

Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. AHSEC Class 11 Power Chapter 4 Installation of Cables Textual Solutions are part of All Subject Solutions. Here we have given AHSEC Class 11 Power Chapter 4 Installation of Cables Textbook Solutions English Medium for All Chapters, You can practice these here.

Installation of Cables

Chapter: 4

SESSION 1: LAYING OF UNDERSTANDING CABLES

Check Your Progress

A. Fill in the blanks:

1. _______________ test is used for the location of faults on lines of low resistance. 

Ans: Murray loop.

2. The current carrying capacity of 150 mm XLPE cable is _______________. 

Ans: 240 Amps.

3. XLPE cables are used for _______________lines. 

Ans: High Tension (HV).

4. _______________are used to lay down the HV cables.

Ans: Erection tools and pulleys.

B. Write short notes on:

1. Pulling method of cables.

Ans: The cable drum must be mounted on jacks and the cable rolled off the drum gently avoiding kinks and twists.The free end in the case of heavy cables may be pulled with the help of a winch. Laying of cable in an open trench presents no serious difficulty. The cable is first placed on rollers laid in the trench or on the ground above, which is then transferred to the bed of the trench. When laying cables in pipes and ducts, care should be exercised so as to not damage them during installation.

2. XLPE cable.

Ans: XLPE cable means cross-linked polyethylene insulated aluminium conductor armoured cable. In XLPE cable, stranded aluminium conductor is first screened in the form of a semi-conducting extrusion which provides a smooth conductor surface and prevents formation of cavities at the surface of the conductor when the cable is subjected to bending. The screened conductor is insulated with an extruded XLPE compound.The insulation is further screened with layer of nonmetallic semiconducting material and over that a non-magnetic metallic screen in the form of copper or aluminium tape is applied. An important advantage of XLPE as insulation for medium and high voltage cables is their low dielectric loss. The dielectric loss factor is about one decimal power lower than that of paper insulated cables and about two decimal powers lower than that of PVC insulated cables. Since the dielectric constant is also more favourable, the mutual capacitance of XLPE cables is also lower, thus reducing the charging currents and earth-leakage currents in networks without the rigid star point earthing.

3. Disadvantages of PILCA cable.

Ans: Disadvantages of PILCA are: 

(i) Heavy due to lead sheathing. 

(ii) Less flexible.

(iii) Poor resistance to vibration. 

(iv) Difficulty in sealing and joining.

4. Advantages and disadvantages of underground cable.

Ans: Advantages of Underground Power Cable System:

(i) Selection of route length is easy and simple

(ii) Safety factor is very high

(iii) Maintenance cost is almost negligible

(iv) It has a good power factor

(v) It can be laid across zigzag and sharp bend routes with care

Disadvantages of Underground Power Cable System:

(i) In case of any fault, it takes a lot of time to repair.

(ii) Costly in comparison to the overhead transmission system because of its initial cost and laying methods.

(iii) Additional load cannot be taken up by the existing cables, hence necessitates the laying of new cables in case of load expansion.

C. Short answer questions:

1. Classify various types of cables.

Ans: Types of Cables:

Cables are named according to the formation, voltage and material used. They are also named according to their use, that is, low tension or high tension cables, etc., as per voltage and single core, two cores, three cores, 3 1/2 core, etc.

Types of cables are classified in different ways on the basis of their uses, voltage and type of insulation used for their construction.

(i) PVC (Polyvinyl Carbide Cable).

(ii) PILCA (Paper Insulated Lead Covered Armoured Cable).

(iii) XLPE (Cross-linked Poly Ethylene Cable.

2. List the steps of cable laying.

Ans: steps of cable laying:

(i) Mount the cable drum on jacks and roll off gently, avoiding kinks and twists.

(ii) For heavy cables, pull the free end with a winch.

(iii) Place the cable on rollers laid in/above the trench.

(iv) Transfer the cable from rollers to the bed of the trench.

(v) When laying in pipes/ducts, exercise care to avoid damage.

(vi) Prepare a sand bed in the trench.

(vii) Lay the cable over the sand bed.

(viii) Cover the cable with cement-concrete ducts or bricks for protection.

(ix) Dress/backfill with soil after protection.

(x) Fix MS route markers at fixed points along the cable route.

3. List tools and equipment required for cable laying activities.

Ans: (i) Many tools are used for cable laying: These include cable pulling winch, cable guiding device and cable pulling grip, etc.

(ii) Cable gets twisted during the laying process: Drums are used to check or avoid twisting of cables. Cable drums help the technicians with the laying of cables. Similarly angle rollers are also used for laying the cable.

(iii) Other tools for cable laying are: Cable pulling winch, Cable guiding device, cable pulling grip, etc.

SESSION 2: LAYING OF AB CABLES

Check Your Progress