FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
System for monitoring the health of a lightning arrestor
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Pasumarthi Umamahesh and Pardeshi Suraj Kumar, of Crompton Greaves Ltd, Electronic Design Centre, CG Global R&D Centre Center, Crompton Greaves Limited, Kanjur Marg, Mumbai 400 042, Maharashtra, India; both Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of lightning arrestors and systems for monitoring its health, thereof
Background of the Invention:
A lightning arrester is a device used on electrical pc>wer systems to protect the insulation on the system from the damaging effect of lightning. Lightning arrestors or surge protectors are designed to be reliable with extreme thresholds of working. They are designed to work efficiently or maintain their life over a specified time period or over the number of time surges are handled.
Environmental conditions essay an important role in governing their life and health status. If a lightning arrestor malfunctions, its repercussions may be felt on all the associated equipment which need to be protected from the surge, thus causing irreparable damage.
For use in a High Voltage line, a lightning arrestor or a plurality of lightning arrestors are placed at pre-defined locations through the line.
In standard monitoring devices of the prior art, it rias been observed that the electrical components used for monitoring are nominal components not capable of

aptly verifying the status or include interference components which led to erroneous reading.
Prior Art:
The prior art documents US7336193, KR2008102083, KR20040061774, US4908729 disclose the concept of health monitoring or electrical degradation of a lightning arrestor by monitoring leakage or ground current using current transformer.
However, accuracy and reliability of prediction is an issue in these systems.
Objects of the Invention:
An object of the invention is to critically and accurately detect the health of a lightning arrestor.
Another object of the invention is to detect the reliability of the arrestor.
Yet another object of the invention is to predict the failure time of the arrestor, in good time.
Still another object of the invention is to verify the reliably of arresting surges at any time or whether the arrester has been damaged or is at risk of failure.

Summary of the Invention:
According to this invention, there is provided a system for monitoring the health of a lightning arrester, in communication with a High Voltage line, said system comprises:
- zero flux current transformer adapted to be connected in series with said lightning arrestor in order to collect the leakage current signal across the ground terminal of lightning arrestor and transfers the same to further blocks of the system;
- signal condition block adapted to condition the received input signal and amplify said signal to a measurable range;
- harmonic computation block adapted to compute the 3rd and 5th harmonic component of the leakage current; and
- parameter computation block adapted to compute the current related health parameters of the lightning arrestor using said computed harmonic components.
Typically, said parameter computation block includes a surge current block adapted to compute surge current parameter of said lightning arrestor.
Typically, said parameter computation block includes a leakage current block adapted to compute leakage current parameter of said lightning arrestor.
Typically, said parameter computation block includes a count of surge block adapted to compute count of surge parameter of said lightning arrestor.

Typically, said parameter computation block includes a health of surge counter block adapted to compute health of surge counter parameter of said lightning arrestor.
Typically, said parameter computation block includes a remaining number of lightning spikes block adapted to compute remaining number of lightning spikes parameter of said lightning arrestor.
Brief Description of the Accompanying Drawings:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic block diagram of the system for monitoring the health of a lightning arrestor.
Detailed Description of the Accompanying Drawings:
According to this invention, there is provided a system for monitoring the health of a lightning arrestor.
Figure 1 illustrates a schematic block diagram of the system for monitoring the health of a lightning arrestor (LA).
Typically, the lightning arrestor is connected to a High Voltage line (HV).

In accordance with an embodiment of this invention, there is provided a zero flux current transformer (ZFCT) adapted to be connected in series with the lightning arrestor ground connector. The ZFCT collects the leakage current across the ground terminal of lightning arrestor and transfers the same to further blocks of the system.
In accordance with another embodiment of this invention, there is provided a signal condition block (SCB) adapted to amplify the given input signal to a measurable range because the leakage current across the LA ground terminal will be in micro amperes, so signal conditioning circuit amplifies the signal and sends it to next stage.
In accordance with yet another embodiment of this invention, there is provided a harmonic computation block (HCB) adapted to compute the 3rd and 5th harmonic component of the leakage current.
In accordance with still another embodiment of this invention, there is provided a parameter computation block (PCB) adapted to compute the current related health parameters of the lightning arrestor such as surge current (SC), leakage current (LC), count of surge (COS), health of surge counter (HSC), remaining no of lightning spikes (NKS) and the like. All these shall be computed based on the 5th harmonic component of the leakage current.
The technical advancement of this invention lies in the computation of 5th harmonic component which is further utilized for assessing the health. In today's power system scenario, 3rd harmonic component is a nominal component which

always exists in the system voltage; so LA leakage current normally carries the same 3rd harmonic current. Performing analysis with 3rd harmonic parameter will not give any accurate results, and especially at the level of micro-amperes and milli-amperes current, it will give false results.
The invention has been described with reference to the aforesaid specific embodiments. It should be noted that the example(s) appended above illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the present invention.

We claim,
1. A system for monitoring the health of a lightning arrestor, in communication with a High Voltage line, said system comprising:
- zero flux current transformer adapted to be connected in series with said lightning arrestor in order to collect the leakage current signal across the ground terminal of lightning arrestor and transfers the same to further blocks of the system;
- signal condition block adapted to condition the received input signal and amplify said signal to a measurable range;
- harmonic computation block adapted to compute the 3rd and 5th harmonic component of the leakage current; and
- parameter computation block adapted to compute the current related health parameters of the lightning arrestor using said computed harmonic components.

2. A system as claimed in claim 1 wherein, said parameter computation block includes a surge current block adapted to compute surge current parameter of said lightning arrestor.
3. A system as claimed in claim 1 wherein, said parameter computation block includes a leakage current block adapted to compute leakage current parameter of said lightning arrestor.
4. A system as claimed in claim 1 wherein, said parameter computation block includes a count of surge block adapted to compute count of surge parameter of said lightning arrestor.

5. A system as claimed in claim 1 wherein, said parameter computation block includes a health of surge counter block adapted to compute health of surge counter parameter of said lightning arrestor.
6. A system as claimed in claim 1 wherein, said parameter computation block includes a remaining number of lightning spikes block adapted to compute remaining number of lightning spikes parameter of said lightning arrestor.