The demand factor is defined as the ratio of the maximum demand of a system (or part of a

system) to the total connected load for that part being considered. Different loads have
different demand factors. The demand factor is always equal to or less than one.
The characteristic impedance or surge impedance (usually written Z 0) of a uniform
transmission line is the ratio of the amplitudes of voltage and current of a single wave
propagating along the line; that is, a wave travelling in one direction in the absence of
reflections in the other direction.
A sag template is specifically design for transmission line according to their voltage
levels. According the voltage levels and the conductor used there are specific design
conditions are used.Sag Template is a very important feature for the surveyor by the
help of which the position of tower can be decided on the Survey Chart so as to
conform to the limitations of specified minimum ground clearance required to be
maintained as per prevailing national rules, between the line conductor to ground
telephone lines, buildings, streets, navigable canals, power lines, or any other object
coming under or near the line and the limitation of vertical load coming on any
particular tower.
Grading of shielding typically refers to the classification or evaluation of the effectiveness of
a material or structure in providing protection against electromagnetic interference (EMI) or
electromagnetic radiation. In the context of shielding, grading involves assessing how well a
shielding material or enclosure can block or attenuate electromagnetic fields.
The Stringing chart represents a graph of tension sag vs temperature, which is used in the
electrical industry to determine the sag of overhead conductors. It is also known as a
tension-temperature chart. Tension vs Temperature. The graph shows the relationship
between the tension and temperature of the conductor.
The Stringing chart represents a graph of tension sag vs temperature, which is used in the
electrical industry to determine the sag of overhead conductors. It is also known as a
tension-temperature chart. Tension vs Temperature. The graph shows the relationship
between the tension and temperature of the conductor.
The load curves help in selecting the size and the number of generating units of the power
station. The load curves help in preparing the operation schedule of the power station. That
means, to determine the sequence and time for which the various generating units in the
power station will be put in operation.
Diversity factor: It is the ratio of the sum of the individual maximum demands of the various
subdivisions of a system (or part of a system) to the maximum demand of the whole system
(or part of the system) under consideration.
Capacity factor: The ratio of the electrical energy produced by a generating unit for the
period of time considered to the electrical energy that could have been produced at
continuous full power operation during the same period.
Tuned power line is the line in which the receiving - end voltage and current are equal to
corresponding sending end values so that there is no voltage drop on load. this is made
possible by cancelling natural series inductance and shunt admittance effects by placing
series capacitors and shunt inductors .
Cables can be classified into various categories, depending on their different uses and
structures. Some types are coaxial cables, twisted pairs, optical fibers, patch cables, power
cables, data cables, etc
the thermal resistance of a cable, often denoted as Rθ or Rₜ ₕ , refers to the ability of the
cable to resist the flow of heat. It is a measure of how well a cable can conduct heat from
one point to another. Thermal resistance is typically expressed in units of degrees Celsius
per watt (°C/W).

The thermal resistance of a cable depends on various factors, including the material
properties of the cable, its dimensions, and the surrounding environment. The thermal
resistance is particularly important in applications where heat dissipation is a concern, such
as in power cables, electronic cables, or any situation where the cable may be subject to
temperature variations.

A load factor is the ratio of the average electric load to the peak load over a period of time.
The load factor is the actual kilowatt-hours delivered on a system in a given period of time,
as opposed to the total possible kilowatt-hours that could be delivered in a given period of
time.
In electromagnetism, skin effect is the tendency of an alternating electric current (AC) to
become distributed within a conductor such that the current density is largest near the
surface of the conductor and decreases exponentially with greater depths in the conductor.
Bundled conductor are those conductors which form from two or more stranded conductors,
bundled together to get more current carrying capacity. By using bundle conductors instead
of the single conductor in the transmission line increases the GMR of the conductors.
Reserve capacity is a backup energy generation capacity that is used by the electric grid in
the occurrence of unexpected fault such as the unavailability of a power plant. Energy
storage systems have the ability to provide this service and are used to offset or reduce
costs incurred for generation of reserve capacity.
The Kelvin's law states that the most economical size of a conductor is that for which annual
interest and depreciation on the capital cost of the conductor is equal to the annual cost of
energy loss."
Transmission efficiency refers to the effectiveness with which a system or medium transfers
energy or information from one point to another. The concept is applicable across various
domains, including energy transmission, data communication, and signal transmission.
The most common types of insulators used to assist overhead power lines are: i) pin
insulators; ii) post insulators; iii) spool/shackle insulators; iv) stay insulators; and v)
suspension insulators.
The utilization factor or use factor is the ratio of the time that a piece of equipment is in use
to the total time that it could be in use. It is often averaged over time in the definition such
that the ratio becomes the amount of energy used divided by the maximum possible to be
used.
A composite conductor consists of two or more strands of different metals, such as
aluminum and steel, or copper and steel (i.e., ACSR, ACAR, AWAC). A conductor consisting
throughout its length of two or more metal conductors providing parallel paths sharing the
load. The light weight, lesser degree of thermal expansion and high tensile strength of
carbon fiber means less is required to support cables. This allows for more conducting
aluminum in the conductor and therefore increased transmission capacity.
in electrical engineering, the Ferranti effect is the increase in voltage occurring at the
receiving end of a very long (> 200 km) AC electric power transmission line, relative to the
voltage at the sending end, when the load is very small, or no load is connected. It can be
stated as a factor, or as a percent increase.It was first observed during the installation of
underground cables in Sebastian Ziani de Ferranti's 10,000-volt AC power distribution
system in 1887. The Ferranti effect is more pronounced the longer the line and the higher
the voltage applied. The relative voltage rise is proportional to the square of the line length
and the square of frequency. The Ferranti effect is much more pronounced in underground
cables, even in short lengths, because of their high capacitance per unit length, and
lower electrical impedance.

The phenomenon of ionisation of surrounding air around the conductor due to which
luminous glow with hissing noise is rise is known as the corona effect. Air acts as a dielectric
medium between the transmission lines. In other words, it is an insulator between the current
carrying conductors.

Feeder transmits power from Generating station or substation to the distribution points. They
are similar to distributors except the fact that there is no intermediate tapping done and
hence the current flow remains same at the sending as well as the receiving end.

Classification of Cables
Classification of cables can be done in two ways according to
 on the basis of insulating material used in their manufacture,
 on the basis of voltage for which they are manufactured.
Classification of Cables Based on Voltage

However, the classification of cables on the basis of voltage is more common, according to
which they can be divided into the following categories:
 Low-tension cables — up to 1000 V
 High-tension cables — the operating voltage of high tension cables is up to
11000 V
 Super-tension cables — the operating voltage of super tension cable is from
22 kV to 33 kV
 Extra high-tension cables — from 33 kV to 66 kV
 Extra super voltage cables — beyond 132 kV
Also, electrical cable classification can be done on the basis of their construction as under:

 Belted cables — up to 22 kV
 Screened cables — from 22 kV to 66 kV
 Pressure cables — beyond 66 kV
A sag template is specifically design for transmission line according to their voltage
levels. According the voltage levels and the conductor used there are specific design
conditions are used.Sag Template is a very important feature for the surveyor by th e
help of which the position of tower can be decided on the Survey Chart so as to
conform to the limitations of specified minimum ground clearance required to be
maintained as per prevailing national rules, between the line conductor to ground
telephone lines, buildings, streets, navigable canals, power lines, or any other object
coming under or near the line and the limitation of vertical load coming on any
particular tower.
Surge impedance loading, commonly called SIL, is a quantity used by system operat ors as a
benchmark to determine whether a transmission line is acting as a capacitance that injects
reactive power (VARs) into the system or as an inductance that consumes VARs, thus
contributing to reactive power losses in the system.

Some of the effects of ice and wind on sag include:

 The weight per unit length of the conductor is changed when the wind blows
at a certain force on the conductor and ice accumulate around the conductor.
 Wind force acts on the conductor to change the conductor self-weight per unit
length horizontally in the direction of the airflow.
 Ice loading acts on the conductor to change the conductor self-weight per unit
length vertically downward.
 Considering wind force and ice loading both at a time, the conductor will have
a resultant weight per unit length.
 The resultant weight will create an angle with the ice loading down ward
direction.
skin effect, in electricity, the tendency of alternating high-frequency currents to crowd toward
the surface of a conducting material. This phenomenon restricts the current to a small part of
the total cross-sectional area and so has the effect of increasing the resistance of the
conductor.

High transmission voltage in a power system can have both positive and negative effects on
the economy, and the impact depends on various factors and considerations. Here are some
effects to consider:

Positive Effects:

1. Reduced Transmission Losses: High transmission voltage allows for the efficient
long-distance transmission of electricity. With higher voltages, there is a proportional
reduction in the I2R losses (where I is the current and R is the resistance), which
means that less power is lost as heat during transmission. This can result in higher
overall system efficiency and lower energy losses.
2. Economic Long-Distance Power Transmission: Higher transmission voltages
enable the economic transmission of electricity over longer distances. This is
particularly important for transmitting power from remote power generation facilities,
such as hydroelectric plants or large-scale wind farms, to population centers where
the electricity is needed.

Negative Effects:

1. High Initial Capital Costs: Building and maintaining high voltage transmission
infrastructure can involve significant upfront capital costs. This includes the cost of
transformers, switchgear, and other equipment designed to handle high voltages.
However, these costs may be justified by the long-term benefits.
2. Increased Complexity and Maintenance Costs: High voltage transmission
systems are more complex and require specialized equipment. The maintenance and
operational costs associated with high voltage infrastructure may be higher
compared to lower voltage systems.
The use of self geometrical mean distance (abbreviated as self-GMD) and mutual
geometrical mean distance (mutual-GMD) simplifies the inductance calculations, particularly
relating to multi conductor arrangements. The symbols used for these are respectively Ds
and Dm.

Self GMD is also called GMR. GMR stands for Geometrical Mean Radius. GMR is calculated
for each phase separately. self-GMD of a conductor depends upon the size and shape of the
conductor. GMR is independent of the spacing between the conductors.

The mutual-GMD is the geometrical mean of the distances form one conductor to the other
and, therefore, must be between the largest and smallest such distance. In fact, mutual-
GMD simply represents the equivalent geometrical spacing.

3-phase 4-wire: This system uses star-connected phase windings and the fourth wire or
neutral wire is taken from the star point. If the voltage of each winding is V, then the line-to-
line voltage (line voltage) is √3V and the line-to-neutral voltage (phase voltage) is V.three
phase four wire system is used for power supply distribution in cities and villages as widely.
In primary side is used delta winding and secondary side is used star winding. Star winding
is so important for getting neutral point so neutral point is important for equipment utilization.

Transposition of conductors is meant the exchanging of the position of the power conductors
at regular intervals along the line, so that each conductor occupies the original position of
every other conductor over an equal distance. Because of the inducing voltages, the
magnetic field exists in the conductor which causes the interference in the line. This can be
reduced by continually exchanging the position of the conductor, which can be done by
transposition the conductors.

There are 5 types of insulators used in transmission lines as overhead insulation:

1. Pin Insulator
2. Suspension Insulator
3. Strain Insulator
4. Stay Insulator
5. Shackle Insulator
Pin, Suspension, and Strain insulators are used in medium to high voltage systems. While
Stay and Shackle Insulators are mainly used in low voltage applications.

The distribution system usually includes an electrical installation of a building which is

connected to the low-voltage distribution network consisting of a step-down transformer
substation and an overhead line or an underground cable .Power sources can also be: a
local power plant, a separate small power generator driven by an internal combustion
engine, and even an isolation transformer, on the basis of which the IT system is
implemented in a part of the building’s electrical installation. However, the listed power
sources are exceptions to the general rule. In the vast majority of cases in the low-
voltage distribution networks to which the building installation is connected, the power
sources are transformers installed in step-down transformer substations.

The power plant, transformer, transmission line, substations, distribution line, and distribution
transformer are the six main components of the power system. The power plant generates
the power which is step-up or step-down through the transformer for transmission.
Composite Conductor?
In Composite conductors sub conductors touch each other. Composite conductors are
typically stranded conductors. In Composite conductors different elements are used (In
ACSR conductors aluminum has the properties of light weight, good conductivity and
rutlessness and steel has the property of high tensile strength). Composite conductors are
employed as they are flexible compared to solid conductor. Composite conductors reduce
proximity effect and also reduces skin effect up to certain extent.
Bundled Conductor?
Bundled conductors are employed in Extra High Voltage (EHV) transmission as at higher
voltages corona effect is significant. In bundled conductors sub conductors are placed as
certain distance throughout the transmission lines. This reduces the corona discharge loss
and interference with the communication lines nearby.

in the context of overhead transmission lines, various constants and parameters are used to
describe the electrical, mechanical, and thermal properties of the system. Here are some of
the key constants and parameters commonly associated with overhead transmission lines:

1. Resistance (R): The resistance of the conductor is a fundamental parameter that

represents the opposition to the flow of electrical current. It is usually expressed in
ohms per unit length (ohms/meter).
2. Reactance (X): Reactance is a measure of the opposition to the flow of alternating
current due to the inductive and capacitive components of the transmission line. It is
typically expressed in ohms per unit length (ohms/meter).
3. Inductance (L): Inductance represents the ability of the transmission line conductors
to store magnetic energy when current flows through them. It is measured in henrys
per unit length (henrys/meter).
4. Capacitance (C): Capacitance represents the ability of the transmission line
conductors to store electrical energy in an electric field. It is measured in farads per
unit length (farads/meter).
5. Impedance (Z): Impedance is the total opposition that a circuit presents to the flow
of alternating current. It includes both resistance and reactance and is expressed in
ohms per unit length (ohms/meter).
6. Velocity of Propagation (v): The velocity at which electromagnetic waves travel
along the transmission line. It is usually expressed as a fraction of the speed of light.
7. Per-Unit Length Parameters: Many of the parameters mentioned above are often
expressed on a per-unit length basis, allowing for convenient comparison and
analysis regardless of the actual length of the transmission line.
8. Conductance (G): Conductance represents the ability of the transmission line to
conduct current and is the reciprocal of resistance. It is measured in siemens per unit
length (siemens/meter).
9. Thermal Constants: These include parameters related to the thermal behavior of
the transmission line, such as the thermal resistance and thermal capacity.
10. Sag Constants: Parameters related to the sag (vertical distance) of the conductors
due to the weight of the transmission line. Sag constants help in calculating the sag
under different loading conditions
.
The sag of a transmission line is the vertical distance between the lowest point of the
conductor and a straight line between the two supports. The sag is influenced by factors
such as the tension in the conductor, the weight of the conductor per unit length, and
environmental conditions. For a transmission line supported between two supports of the
same height, we can derive an expression for the sag using basic physics and
trigonometry.Let's consider a simple model where the transmission line is a perfectly flexible
and uniform cable, and the supports are at the same height. Assume the supports are
located at points A and B, and the line is hanging under its weight.
insulators are crucial components in electrical systems, serving to isolate conductive
materials and prevent the unintended flow of electric current. Failures of insulators can lead
to electrical breakdowns, system outages, and safety hazards. Several factors can
contribute to the failure of insulators:

1. Contamination:
2. Moisture:
3. Mechanical Damage:.
4. Tracking and Erosion:
5. Corona Discharge:.
6. Thermal Stress:
7. Ageing:
8. Poor Design or Material Quality:
9. Overvoltage Conditions:
10. Improper Installation:.
11. Chemical Attack:

Busbar systems are essential components in electrical power distribution and are used to
conduct and distribute electrical power within a facility or system. Different types of busbar
systems exist to meet various requirements based on factors such as current-carrying
capacity, voltage levels, and system layout. Here are several types of busbar systems:

1. Single Busbar System:.

2. Single Busbar System with Sectionalization:
3. Double Busbar System:
4. Double Busbar System with Transfer Bus:
5. Ring Bus System:
6. Breaker and a Half System:
7. Sectionalized Double Busbar System:.
8. Duplex Bus System:.
9. Multi-Tie Breaker System
The modified statement of Kelvin's law suggests that the most economical conductor size is
that for which the annual cost of energy loss is equal to the annual interest and depreciation
for that part of capital cost which is proportional to the conductor size.

Limitations Of Kelvin's Law

1. It is quite difficult to estimate the energy loss in the line without actual load curves
which are not available at the time of estimation.
2. Interest and depreciation on the capital cost cannot be determined accurately.
3. The conductor size determined using this law may not always be practicable one
because it may not have sufficient mechanical strength.
4. This law does not take into account several factors like safe current carrying
capacity, corona loss etc.
5. The economical size of a conductor may cause the voltage drop beyond the
acceptable limits.
Methods Of Voltage Control In Power System
1. Using excitation control or voltage regulators at generating stations
2. By using tap changing transformers
3. Using induction regulators
4. By using shunt reactors
5. By using shunt capacitors
6. Using synchronous condensers
7.
An interconnected system in the workplace is the process of linking technological resources,
manpower, and other items of capital together. It can improve efficiency and accountability
throughout the organization
Drawbacks of Interconnection system: Heavy currents flow under faulty condition on the
transmission lines with a consequent expensive circuit breakers are essential in
interconnected system. The generators of all the inter-connected grid must function at same
frequency and in a synchronized method

Feeders
The feeder is the electrical conductor that connects the sub-station to the area where power
is to be distributed. The current in a feeder remains same since, no tappings are taken from
the feeder. While designing a feeder the main consideration is the current carrying capacity.
In the figure below feeder is indicated using blue color.

Distributor
A distributor is the electrical conductor from which tapping are taken for supply to the
consumers. From a feeder many tappings are taken, due to which current through a
distributor is not constant. While designing distributors, power engineers are primarily
concerned with voltage drop. Since a voltage variation higher than ± 6% is undesired. In the
figure distributor is indicated in green lines.

Service mains
The service mains are small electrical conductor cables that connect the distributor to the
consumers’ terminals. In the figure below service mains are indicated in red color. The
consumers loads are indicated in golden colors.

The flux linkage of a conductor carrying current can be expressed in terms of the magnetic
field produced by the current. The flux linkage includes both the internal and external
components, where the internal component refers to the magnetic flux within the conductor,
and the external component refers to the magnetic flux outside the conductor.

The ABCD parameters are used to describe the transmission characteristics of a two-port
network, and they are commonly applied to analyze transmission lines. For a medium
transmission line (also known as a distributed parameter transmission line), the ABCD
parameters are expressed in terms of the transmission line's primary electrical parameters:
series impedance (Z), shunt admittance (Y), propagation constant (γ), and characteristic
impedance (Z₀).

The power circle diagram is a graphical representation used in electrical engineering to

analyze and understand the power flow, power factor, and reactive power in an AC power
system. It is particularly helpful in visualizing the relationships between active power (real
power), reactive power, and apparent power. Here are some common uses of the power
circle diagram:

1. Power Factor Analysis:.

2. Visualization of Power Components:
3. Identification of Power Factor Improvement Strategies:
4. Analysis of Load Conditions:.
5. Determination of Load Compensation:
6. Education and Training:
7. Power System Design:
Transmission lines carry high voltages from the generating stations to primary transmission
stations, secondary transmission stations, primary distribution stations, and secondary
distribution stations. These lines are classified based on their location (overhead or
underground), length, and voltage rating