FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A system and method for transformer health analysis
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400030, Maharashtra, India, an Indian Company
INVENTORS
Patil Shubhangi Sachin and Venkatasami Athikkan, both of Crompton Greaves Ltd, Condition Monitoring and Diagnostic Centre (CMDRC), CG Global R&D Centre, Kanjur Marg (East), Mumbai 400042, Maharashtra, India, both are Indian nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which
it is to be performed:

FIELD OF THE INVENTION
The present invention relates to a system and method for transformer health analysis.
BACKGROUND OF THE INVENTION
Electric power transmission is a process in the delivery of electricity to consumers. In general, the term "electric power transmission" refers to the bulk transfer of electrical power from place to place, for example, between a power plant and a substation near a populated area. Due to the large amount of power involved, electric transmission normally takes place at high voltage (110 kV or above). Transformers are used at the substations to step the voltage down to a lower voltage for distribution to commercial and residential users.
Owing to the huge dependency on electricity run devices in our day to day life, any disruption in the electric supply may prove to be expensive and catastrophic, especially in an environment where mission critical equipments are being used. It is therefore a norm nowadays to continuously monitor the health of the transformers through a variety of routine tests such as DGA test, electrical test, SFRA test, oil test etc. Usually, results of each of these tests cannot be obtained instantaneously. Specific datasets for the purpose of each test is first collected. Subsequently, the datasets are worked upon based on established mathematical models and theories to derive an output indicative of the health of the transformer. The output is then analyzed by an expert to interpret the health of the transformer.

Human nature, workload and the complexity involved in the analysis of each set of data can cause otherwise responsible individuals to postpone the analysis of the set of the data collected to perform a specific test. The usefulness of collecting datasets for a test is thus defeated when the enormous quantity of data is not analyzed/interpreted in a timely manner. Consequently, certain conditions can go undetected until a catastrophic event occurs.
Online transformer monitoring systems are knovvn for monitoring transformer operations to detect malfunctions. Existing online transformer monitoring systems are based on directly comparing measured quantities to threshold values (constants). While this allows power producers and distributors to ascertain when certain measured quantities fall outside the threshold values (Standard acceptable limits), this approach generates a relatively large number of false alarms of transformer malfunction. OBJECTS OF THE INVENTION
An object of the invention is to provide a transformer health analysis system and method which automatically determines the health of the transformer quickly and accurately without generating false alarms. DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a transformer health analysis system comprising an interfacing means for receiving transformer test datasets, a processing means comprising at least one auxiliary analysis module, and a main analysis module wherein each auxiliary analysis module is designed to process a dataset based on a pre¬determined mathematical model for deriving an output and the main analysis module is designed to further process each output from the auxiliary analysis modules based on a

pre-determined model of comparison for deriving an output indicative of health status of the transformer and an outputting means for outputting the output indicative of the health status of the transformer and/or said outputs from the auxiliary analysis modules.
According to the invention there is provided a transformer health analysis method comprising the steps of obtaining a plurality of transformer test datasets; processing each dataset based on a pre-determined mathematical model for deriving an output; further processing each outputs from the auxiliary analysis modules based on a pre-determined model of comparison for deriving an output indicative of health status of the transformer and outputting the output indicative of the health of the transformer and/or said outputs from the auxiliary analysis modules.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 illustrates a block diagram of the transformer health analysis system according to one embodiment of the invention. The system comprises of an interfacing means 1, a processing means 2 and an outputting means 3. The interfacing means 1 is adapted to receive transformer test datasets manually by a user through a user interface 4 such as key board. Alternatively, the transformer test datasets are obtained through transformer testing instruments 5 interfaced with the interfacing means directly or through Internet or other communication links. Each transformer test dataset corresponds to a specific test to be conducted on the transformer. The processing means 2 comprises often auxiliary analysis modules (6-15) and a main analysis module 16. Each auxiliary module - i.e. the Voltage Ratio Test Module 6, Leakage Reactance Test Module 7,

Magnetic Balance Test Module 8, Insulation Resistance Test Module 9, Winding Resistance Test Module 10, C and Tan delta Test Module 11 for Bushing, C and Tan delta test Module 12 for Transformers, Sweep frequency response analysis (SFRA) Test Module 13, Excitation current test module 14 and thermo vision test module 15 corresponds to an algorithmic mathematical model of the specific test to be conducted on the transformer for deriving an output by processing the received datasets. For example, the Leakage Reactance Test Module 7 derives the %impedance value through the formula %impedance = (V1/V2)*(I2/I1)*100 after receiving the corresponding datasets comprising of VI, V2, II, 12 - the voltage and current ratings for two windings. The main analysis module 16 analyzes each output obtained from the auxiliary analysis modules (6-15) to determine the current health of the transformer. The analysis of outputs of each auxiliary module in the main analysis module 16 is based on different pre-configured comparison models. For example, analysis of one output from an auxiliary module may be based on comparing the output value with a reference value and subsequently determining the health of the transformer stored corresponding to the output of the comparison. Whereas, analysis of the other output from the other auxiliary analysis module may be based on determining the difference between the output and the reference value and subsequently determining the health of the transformer stored corresponding to the difference between the output and the reference value. With respect to the example stated above, after deriving the %impedance value from the Leakage Reactance Test Module 7, the main analysis module 14 compares the derived %impedance value with a reference %impedance value and calculates the deviation i.e. the difference between the reference and derived %impedance value. The deviation so calculated is then compared

to a database of analysis stored in the system to obtain the corresponding health analysis of the transformer, such as 'transformer healthy or transformer needs attention'. The health of the transformer thus determined is outputted through the outputting means 3 to the user for initiating appropriate action. The outputting means 4 may be a monitor, printer or any such device. The outputting means may also output, along with the health of the transformer, a detailed report of the all the outputs of each auxiliary analysis modules and other general data such as the make, manufacturing year, serial no, vector group etc of the transformer.
According to another embodiment of the invention, the processing means is adapted to convert the datasets into a format readable by the auxiliary analysis module. It will be appreciated by a person skilled in the art that the processing means may have any number of auxiliary modules.
In the method of transformer health analysis, at lea.st one transformer test dataset is first obtained 21 from the transformer testing instruments or other means available. Subsequently, each dataset is processed 22 based on a pre-determined mathematical model and output is derived. For example, the %impedance value is obtained through the formula %impedance = (V1/V2)*(I2/I1)*100 after receiving the corresponding dataset i.e. VI, V2, II, 12 - the voltage and current ratings for two windings of the transformer. Similarly, dataset obtained from a variety of transformer testing instruments are processed to derive a corresponding output. Thereafter, each such output is further processed 23 based on a pre-determined model of comparison to derive an output which being indicative of the health status of the transformer. For example, after deriving the %impedance value, it is compared with a reference %impedance value and a deviation is

derived by calculating the difference between the reference and derived %impedance value. The deviation so calculated is then compared to a database of analysis stored in the system to obtain the corresponding health analysis of the transformer, such as 'transformer healthy or transformer needs attention'. The health of the transformer thus determined is outputted 24 through the outputting means to the user for initiating appropriate action. The outputting means may be a monitor, printer or any such device. The outputting means may also output along with the health of the transformer, a detailed report of the all the outputs of each auxiliary analysis modules and other general data such as the make, manufacturing year, serial no, vector group etc of the transformer.
According to the invention, generation of test reports of the transformer and the corresponding interpretation is made quick, easy and automatic without any human intervention thereby rendering the test reports error free. Also, the cycle time of the generation of the reports and its interpretation is reduced considerably thereby allowing a quick corrective action, if any.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim
1. A transformer health analysis system comprising of
• an interfacing means for receiving transformer test datasets;
• a processing means comprising at least one auxiliary analysis module and a main analysis module wherein each auxiliary analysis module is designed to process a dataset based on a pre-determined mathematical model for deriving an output and the main analysis module is designed to further process each output from the auxiliary analysis modules based on a pre-determined model of comparison for deriving an output indicative of health status of the transformer; and
• an outputting means for outputting the output indicative of the health status of the transformer and/or said outputs from the auxiliary analysis modules.

2. The transformer health analysis system as claimed in claim 1, wherein the transformer test datasets are obtained from transformer testing instruments interfaced with the interfacing means directly or through internet or other communication links,
3. The transformer health analysis system as claimed in claim 1, wherein the interfacing means is adapted to receive the datasets from the user directly through inputting means such as keyboard.
4. The transformer health analysis system as claimed in claim 1, wherein said auxiliary and main analysis modules are configurable.

5. The transformer health analysis system as claimed in claim 1, wherein said outputting means is a monitor for displaying the outputs.
6. The transformer health analysis system as claimed in claim 1, wherein said outputting means is a printer.
7. A transformer health analysis method comprising the steps of obtaining a plurality of transformer test datasets; processing each dataset based on a pre-determined mathematical model for deriving an output; further processing each outputs from the auxiliary analysis modules based on a pre-determined model of comparison for deriving an output indicative of health status of the transformer and outputting the output indicative of the health of the transformer and/or said outputs from the auxiliary analysis modules.
8. The method as claimed in claim 1, wherein the datasets are obtained through transformer testing instruments interfaced with the interfacing means directly or through internet or other communication links.
9. The method as claimed in claim 1, wherein said processing is carried out by means of computer based processor.
Dated this 12th day of November 2009
(Irfan Modi)
Agent for the Applicants
of Khaitan & Co
RegNoIN/PA-1586