To provide the students with an opportunity to acquire knowledge, skills and attitude in the area of transmission and distribution electrical energy with special emphasis on:

- Different types of transmission and distribution systems of electrical energy.
- Comparison of different types of transmission and distribution system.
- Electrical and mechanical design of overhead lines.
- Survey of transmission and distribution line route.
- Performance calculation of overhead transmission line.

*SHORT DESCRIPTION *

Supply system: Different systems of transmission; Aspect of system loss; Mechanical design of overhead lines: support of overhead lines; conductors & conductor materials; Insulators; Effect of sag; Methods for survey of transmission/distribution line route; Voltage distribution of suspension insulator; Corona; Erection of poles and drawing of conductors of overhead line; Electrical design of overhead line: Resistance of the line conductor; Skin effect of transmission line; Effect of inductance on transmission line; Effect of capacitance of overhead transmission line; Performance of transmission lines: Voltage regulation and efficiency of short transmission line.

## DETAIL DESCRIPTION

__Theory__**:**

# SUPPLY SYSTEM

**Understand different systems of transmission of electrical energy.**- Explain the transmission and distribution system of electrical energy.
- Categorize various systems of transmission and distribution of electrical energy.
- Define Feeder and Distributor.
- Compare bet
^{n}feeder & Distributor. - Compare between overhead and underground transmission and distribution system.
- Explain the advantages of high voltage transmission over low voltage transmission.
- Compare the cost of conductor of different overhead systems.
- Compare the cost of conductor of underground system with overhead system.
- Describe the process of choosing the working voltage for transmission and distribution system.
- Calculate the most economic working voltage for transmission of electrical energy.
- Express the equation for the most economic size of conductor by Kelvin’s law.
- Solve problems on Kelvin’s law.
- Describe the limitations to the application of Kelvin’s law.

**Understand different aspects of system loss.**- Explain the term system loss
- List the factors involved in system loss.
- Explain how system loss can be minimized.
- Discuss the most economic power factor.
- Express the equation for most economic power factor.
- Solve problems on most economic power factor.

# MECHANICAL DESIGN OF OVERHEAD LINES

**Understand the supports of overhead lines.**- List the main components of overhead lines.
- Categorize the line supports.
- Describe different types of line supports.
- Mention the characteristics of line supports.
- Describe the vibration dampers.

**Understand the conductors and conductor materials.**- List different types of line conductors used in overhead transmission and distribution lines.
- Mention at least five properties of conductor materials.
- Compare the properties of copper, aluminium and ACSR conductors.

**Understand the line insulators and their characteristics.**- List different types of insulators.
- List insulator materials.
- Describe the propertie of insulators materials.
- Describe the pin and suspension type insulators.
- Compare the advantages and disadvantages of pin and suspension type insulator.
- Mention the uses of different types of insulator.
- List the causes of failure of insulators.
- Explain different types of test of insulators.

**Understand sag and its effect.**- Explain the sag of transmission line.
- List the factors affecting the sag.
- Explain the spacing between conductors and span length.
- Express the deduction of the formula to calculate the sag of conductors between two poles of equal height.
- Express the deduction of the formula to calculate the sag of conductors between two poles of unequal heights considering effect of ice and wind pressure.
- Solve problems on sag of transmission line.
- Explain the effects of vibration on the transmission line and prevention of vibration.
- Describe the measure for the prevention of vibration.

**Understand the methods for survey of transmission / distribution line route.**- List the survey instruments required for survey of transmission / distribution line.
- Explain the uses, errors and accuracy of survey instruments.
- Describe the process of measuring the angles by compass, level and theodolite.
- Explain leveling, alignment, surveying and pegging of the route.
- Explain the methods of measuring vertical and horizontal heights.
- List the principle factors in routing overhead power lines.

**Understand the voltage distribution of suspension insulator.**- Explain string efficiency.
- Describe the methods of improving string efficiency.
- Solve problems on string efficiency.
- Express the deduction of equation for voltage distribution across each unit of a string of suspension insulators.
- Describe the methods of voltage grading in suspension insulators.
- Describe the method of equalization of voltage of suspension insulators by guard ring.
- Solve problems on voltage distribution and voltage grading.

**Understand the phenomenon of corona.**- Define corona of overhead transmission line.
- Discuss the effect of corona.
- Explain at least four factors that affect corona.
- Describe the advantages and disadvantages of corona.
- Express the derivation of the relation for disruptive critical voltage, visual critical voltage and power loss due to corona.
- Discuss the methods for minimizing corona.

**Understand the erection of poles / towers and drawing of conductors of overhead line.**- Describe the procedure of erection of poles of overhead transmission / distribution line.
- Describe the procedure of erection of towers of overhead transmission line.
- Describe the procedure of fixing crossarm and insulator.
- Describe the drawing of conductors of overhead line.
- Describe the erection of stay / guy wire.

# ELECTRICAL DESIGN OF OVERHEAD LINE

**Understand the resistance of line conductor.**- Describe the line constant of transmission line.
- Express the deduction of the equation for calculating resistance of the line conductor.
- Solve problems on the resistance of the line conductor.

**Understand the skin effect of transmission line.**- Explain the skin effect of transmission line.
- Express the equation for calculating skin effect resistance.
- Explain the proximity effect.

**Understand the effect of inductance on transmission line.**- Explain the flux linkage of a conductor due to internal and external flux.
- Express the deduction of the equation for inductance of a single phase and three phase overhead transmission line in terms of Geometrical Mean Distance (GMD) and Geometrical Mean Radius (GMR).
- Solve problems on inductance of single phase and three phase lines.
- Describe the inductance of three-phase line with double circuit.
- Explain the transposition of line conductors.

**Understand the effect of capacitance of overhead transmission line.**- Explain the electric potential of a transmission line.
- Express the derivation of the equation to calculate the capacitance of single phase and three phase overhead transmission line.
- Solve problems on capacitance of single phase and three phase overhead transmission line.
- Explain the capacitance of double circuit three phase overhead line.
- Explain Ferranti effect.

# PERFORMANCE OF TRANSMISSION LINES

**Understand the voltage regulation and efficiency of short transmission line.**- Classify overhead transmission line.
- Express the equation to calculate voltage regulation of overhead short transmission line.
- Express the equation to calculate efficiency of overhead short transmission line.
- Identify the effect of load power factor on voltage regulation and efficiency of overhead short transmission line.
- Draw vector diagram of short transmission line performance calculation.
- Solve problems on voltage regulation and efficiency of overhead short transmission line.

__Practical__**: **

** **

**Survey and estimate the electrical loads of an area.**- Select the area / section of which the electrical loads are to be surveyed.
- Observe and record the load of each point of the area.
- Calculate the amperage of the area and the sub-area.
- Calculate the load of main circuit and sub-circuits.

**Plot the integrated load curve, actual load curve and ideal load curve.**- Draw the integrated load curve.
- Draw the actual load curve.
- Draw the ideal load curve.

**Perform the selection of economical voltage for generation, transmission and distribution of electrical power.**- Select generating voltage.
- Select voltage for transmission and distribution of electrical power.
- Select required type of insulators and poles.

**Prepare the layout diagram of an electrical project.**- Draw the layout of the selected electrical project.
- Draw the complete wiring diagram of the electrical project showing transmission line, distribution line and service mains.
- Indicate the power source.

**Perform the identification of different components of LT and HT over head lines.**- Identify the components of LT over head lines.
- Identify the components of HT over head line.
- Follow safety paractices.
- Prepare a report.

**Perform the measurement of the horizontal distance between poles.**- Collect the instruments/ equipment commonly used in surveying.
- Measure the horizontal distance between poles over different ground conditions using tape and chain.
- Record the measurement of distance.
- Plot the line route showing the measurements.

**Perform the measurement of the angles and heights of poles / towers.**- Select the instruments for measuring angles and heights of poles.
- Measure horizontal angles.
- Measure vertical angles.
- Measure vertical heights of poles / towers.

**Survey and level the power lines.**- Visit an actual high voltage power line route covering a distance of approximately five span.
- Record ground levels, angle of route, interfering obstacles and length.
- Draw a ground profile of the line route, showing the support positions and ground clearance on river crossing and canal crossing.

**Perform the measurement of sag of a transmission / distribution line.**- Fix up the sag boards.
- Set the theodolite in proper position.
- Measure the sag of a transmission / distribution line using theodolite.
- Prepare a report.