THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

A METHOD AND APPARATUS FOR MEASURING HARMONICS IN A
POWER LINE
A) FIELD OF THE INVENTION
1. This invention relates generally to methods and systems for measuring harmonics, and more particularly to, a method and apparams for measuring harmonics in an electrical power line.
B) BACKGROUND OF THE INVENTION
2. This invention relates to a method and apparatus for measuring the harmonics in a power line and displaying the harmonic components as fundamental, 3rd, 5th, 7th harmonic components and so on.
3. In most of the factory environment, power is received from an external source into the factory to a substation. From a substation within the factory the power is then distributed around the factory to various equipments such as, power loom, motors, welding machinery, computers, and the like.
4. To protect the high cost equipments such as the transformers, the equipments attached to the power line, and to prevent from any arc generation, it is quite common that these power distribution systems also are equipped with protective devices such as trip units, circuit breakers, fuses etc. These protective devices are attached to each small branch of the circuitry so that each piece of the equipment is protected and also any problems associated with a machinery

is restricted only to that branch of the factory and does not affect the other parts and functionality of the factory. Thus by providing trip units in each branch and sub-branch of a factory minimize the down time of the entire production of the factory thereby creating increased efficiencies, lower operating and manufacturing costs and the like.
5. Typically, when trip units are utilized, they are used to detect more than just one function. To name a few, trip units monitor functions such as over current, power surge, undesired arc in power line etc. Trip units may be designed to trip just due to large over current conditions caused by short circuit faults as well.
6. There exists a need for as method and apparams for measuring the quality of the power line as a measure of the harmonic components. The lesser the harmonic, better is the quality of power. Hence measurement & display of harmonic enables the user/system to take the decision about continuity of supply. Some protections can be provided or decisions can be made based on the harmonic levels displayed in a display unit.
C) OBJECTS OF THE INVENTION
7. An object of this invention is to provide a method and system for measuring harmonics jn an electrical power line wherein the measured harmonics represent the quality of power line in graphical form.

8. Another object of this invention is to provide a method and system for
measiiring harmonics in an electrical power line wherein the display is visible so
as to easily judge the quality of power supply from a distance.
D) SUMMARY OF THE INVENTION
9. The above-mentioned shortcomings, disadvantages and problems are addressed
herein, which will be understood by reading and studying the following
specification.
10. In one embodiment, a method of measuring harmonics in a power line comprises the steps of determining a plurality of harmonic components in one or more power lines using Fourier transformation analysis, and displaying the harmonic components in a graphical form, wherein the quality of the power line is a direct measure of the magnitude of the harmonic component as displayed in the graph.
11. In another embodiment, an apparatus for measuring the harmonics in a power line comprises a computer program, a display unit, and the computer program is configured to determine a plurality of harmonic components in one or more power lines using Fourier transform analysis for graphically displaying in the display unit.
E) BRIEF DESCRIPTION OF THE DRAWINGS
12. FIG. 1 shows a graph of the measured harmonic components according to one example of this invention.

F) DETAILED DECRIPTION OF THE INVENTION
13. In the following detailed description, reference is made to the accompanying
drawings that form a part hereof, and in which is shown by way of illustration
specific embodiments which may be practiced. These embodiments are
described in sufficient detail to enable those skilled in the art to practice the
embodiments, ands it is to be understood that logical, mechanical, electrical and
other changes may be made without departing from the scope of the
embodiments. The following detailed description is, therefore, not to be taken
in a limiting sense.
14. Various embodiments of this invention provide a method and apparatus for
measuring the harmonics of a power line.
15. The harmonic components are measured and separated as multiple
components using Discrete Fourier Transform coefficients as given in the
equation below

Where k -> harmonic component to find
N -> Npoint DPT
Pi -> 3.14
X(n) -> input samples of wave
N -> 0 to n-1
X(k) -> Kth component in frequency domain.

16. The measured component of the harmonics is displayed on a conventional display unit. For example, the display is in the form of a bar graph.
17. The display unit represents the harmonic levels in a bar graph form at of multiple power lines and points. In one example, the functionalities shown as ESC (1) is for exiting from the graphical display, PREV (2) is for checking the harmonic components of previous power junction or line and NXT (3) is for checking the harmonic components of next power line.
18. The displayed graph of the each harmonic, namely F-> fundamental component, 3 -> third harmonic, 5 -> fifth harmonic, 7 -> seventh harmonic component is scaled to 0-100% with respect to the root mean square (RMS) voltage/current value and are demarked as 20%, 40%, 60% and 80% of the RMS voltage/current value.
19. It should be noted that the magnitude harmonic components represent the quality of electric power. Lesser the magnitude of the harmonic better is the quality of power. Hence measurement & display of harmonic enables the user/system to take the decision about continuity of supply. Some protections can be provided or decisions can be made based on the harmonic levels displayed in the display unit.
20. In one embodiment, an apparatus for measuring the harmonics in a power line comprises a computer program and a display unit. The display unit may be a conventional one and may be attached to a trip unit. Visually interpretable harmonic components are displayed on the display unit and decision can be made based on the observation made from the display. The display is designed

in such a way that user can identify a faulty current flow from a distance rather than looking closely at the numbers.
21. It should be noted that the harmonic levels displayed as bar graphs enables user to visualize the quality of the power line.
22. Thus, various embodiments of the present invention provide a method for measuring the harmonics in an electrical power Une. Further embodiments of this invention provide an apparatus for measuring the harmonics in an electrical power line.
23. It will be obvious for a person of skilled in the art to practice the invention with modifications. However, all those modifications wiU be deemed to be covered within the scope of the invention as covered in the claims hereunder.

G) WE CLAIM:
1. A method of measuring harmonics in a power line comprising the steps of:
(i) determining a plurality of harmonic components in one or more power lines
using Fourier transform analysis; and
(ii) displaying the harmonic components in a graphical form, wherein the quality of the power line is a measure of the magnitude of the harmonic component.
2. A method as claimed in claim 1 wherein the harmonic component in a
predetermined frequency domain is determined using the formula

wherein "k" is harmonic component to find, "N " is Npoint Direct Fourier Transform, "Pi" is equal to 3.14, X(n) is input samples of wave, N is 0 to n-1, X(k) is Kth component in frequency domain
3. A method as claimed in claim 1 wherein displaying comprises providing a means
to select a graph of a desired power line among the plurality of power lines.
4. A method as claimed in claim 1 wherein each harmonic component is scaled to a
predetermined percentage of the RMS value of the voltage or current.
5. A method as claimed in claim 1 wherein the harmonic components comprises odd
harmonic components.

6. A method as claimed in claim 1 wherein the resolution of the display is about 1.25
percent.
7. A method according to claim 1 wherein a trip unit is coupled to the power line and
the harmonic component is determined in the trip unit.
8. An apparatus for measuring the harmonics in a power Hne comprising:
(i) a computer program;
(ii) a display unit;
(iii) said computer program configured to determine a plurality of harmonic components in one or more power lines using Fourier transform analysis for graphically displaying in the display unit.
9. An apparatus as claimed in claim 8 wherein resolurioii of display is about 1.25
percent.
10. An apparatus as claimed in claim 8 wherein each harmonic component is scaled to
a predetermined percentage of the RMS value of the voltage or current.