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
A system for detecting partial discharge location in transformers
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Kumar Santosh Annadurai, Ameer Abdul Quadir and Remje Deepak; all of Crompton Greaves Limited, Advanced Materials and Process Technology Centre, Condition Monitoring & Diagnostic Research Centre, CG Global R&D Centre, Kanjurmarg (East), Mumbai -400042, Maharashtra, India; all 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 transformers.
Particularly, this invention relates to a system for detecting partial discharge location in transformers.
BACKGROUND OF THE INVENTION:
A Transformer is an electrical device that transfers energy from one circuit to another by magnetic coupling without any moving parts. It works on the Principle of Faradays Law of Electromagnetic Induction together with other laws of electricity. When a magnetic flux linked with an electric circuit varies, an electro motive force (voltage) is generated in the electric circuit, proportional to the rate of variation of flux with time.
The basic functional parts of the transformer are a core made of magnetic material, a primary winding, and a secondary winding. The primary winding is connected to a source of an alternating current and the secondary winding is connected to the output. As the alternating current flows through the primary winding, the change in current in the primary windings creates a time-varying magnetic flux in the core, which induces a voltage in the secondary windings.
Windings could be either two or more coupled windings viz. primary and secondary in nature, or a single tapped winding. The wire used is generally a good conductor, like a copper or Aluminum wire with a coating of varnish or some other insulation. Windings basically act as electrical conductors. They are coupled with each other and hence have mutual inductance. The equation for the working of ideal transformer is:

The instantaneous induced EMFs in the various windings are proportional to their number of turns.
Vp corresponds to Primary Voltage.
Vs corresponds to Secondary voltage.
Np corresponds to Number of turns on Primary side.
Ns corresponds to Number of turns on Secondary side.
In an ideal scenario, the number of turns in both the windings equals each other, and the ratio stands as 1. Hence, voltages on either sides of the transformer are ideally the same. To increase the functionality of the transformer, the numbers of turns, number of windings are varied or a single winding may be tapped for an output. This categorizes transformers into step-up, step-down, multiple input/output or Auto mode type.
Transformers are a vital component for many large industries and industrial applications. It is essential to maintain the health of transformers for effective and smooth running of associated equipment.
Frequently, transformer failure can be associated with initiation of partial discharge which leads to complete breakdown in insulation. PD may occur due to ingression of moisture or presence of cavity. This interferes with the inductance and capacitance of the transformer.
The movement of electrical charges through an insulating (dielectric) medium, initiated by electron avalanches is called as electrical discharge. A partial discharge (PD) can be described as a localized electrical discharge that only partially bridges the insulation between conductors and which can or cannot occur adjacent to a conductor. These discharges might occur in

any void between the conductor and the ground. The voids may be located between the conductor and insulation wall, or internal to the insulation itself, or between the outer insulation wall and the ground frame. Once begun, PD causes progressive deterioration of insulating materials, ultimately leading to electrical breakdown. Since power and distribution transformers form important components in the electricity grid, failure of such important components has imposed an alert to monitor the transformer through on-line monitoring system in order to avoid the serious damage to the power system and reduce the cost incurred during the failure.
Each large transformer is independently designed according to client requirement thus causing changes in the geometry of construction. There is, therefore, a need to identify partial discharge locations (with relation to windings or winding taps) without worrying about the geometry of the construction so that repairs can be carried out expeditiously.
PD is located by winding transfer function, which needs the transformer geometry, hence it makes difficult for sensor and system manufacturers to locate PD in each transformers due to its complex construction and drivers' internal, proprietary geometry construction.
Also, since this needs FFT and its other real time features to be analyzed it makes it difficult for developing a system which can locate the PD in a transformer on an online/ real time basis.
There is a need for a PD location system which is independent of the transformer winding geometry or any other complex signal processing on a real time basis.

PRIOR ART:
JP2004056970 discloses a method for diagnosing slack of winding of AC rotary machine.
Location of PD in relation to a multi-winding transformer, especially with respect to leads coming out of transformer housing is not disclosed.
JP2004172174 discloses a system and method for diagnosing pole transformer insulation.
A laser is used in accordance with this document. It locates partial discharge (insulation deterioration); but this technique is not expandable to a multi-winding transformer.
US6178386 discloses a Method and apparatus for fault detection. A partial discharge fault in a transformer tank is determined by sensing supersonic vibrations at a multiplicity of points about the tanks and establishing a threshold amplitude and a frequency range for pulse vibrations to be evaluated. Sensitivity and noise can be an issue whilst dealing with such supersonic noise vibrations.
JP60100060 discloses a partial discharge detecting apparatus.
This relates to acoustical detection which is prone to noise, and hence,
reduces efficiency and accuracy of PD location determination.
OBJECTS OF THE INVENTION:
An object of the invention is to provide a Partial Discharge location system which is independent of the transformer winding geometry.

Another object of the invention is to detect Partial Discharge in a transformer with unknown geometry.
Yet another object of the invention is to locate Partial Discharge in a transformer with unknown geometry.
Still another object of the invention is to detect and locate Partial Discharge in a transformer with unknown geometry without the use or need of any complex signal processing on a real time basis.
SUMMARY OF THE INVENTION:
According to an embodiment of this invention, there is provided a system for
detecting partial discharge location in transformers, having at least two
windings and leads extending therethrough, said system comprises:
1) calibration means adapted to calibrate said system for testing, said
calibration means including pulse input means for providing High
frequency pulse to each of said windings through said leads and
obtaining sensed inputs at each of the remainder of said windings
correspondingly, said calibration means comprising:
a. first input means adapted to input a first calibration amplitude voltage
to a first winding and a second sensing means adapted to sense second
amplitude with respect to said first calibration amplitude at said
second winding and a third sensing means adapted to sense third
amplitude with respect to said first calibration amplitude at said third
winding;
b. second input means adapted to input a second calibration amplitude
voltage to a second winding and a first sensing means adapted to
sense first amplitude with respect to said second calibration amplitude

at said first winding and a third sensing means adapted to sense third amplitude with respect to said second calibration amplitude at said third winding;
c. third input means adapted to input a third calibration amplitude
voltage to a third winding and a first sensing means adapted to sense
first amplitude with respect to said third calibration amplitude at said
first winding and a second sensing means adapted to sense second
amplitude with respect to said third calibration amplitude at said
second winding;
d. first database means adapted to store each of said input calibration
amplitude voltages and said corresponding sensed amplitude voltages
in a matrix format;
e. first computation means adapted to compute calibration ratios of
amplitude voltages according to pre-defined equations; and
f second database means adapted to store each of said computed calibration ratios; 2) testing means adapted to test said system for partial discharge, said testing means including pulse input means for providing High frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly, said testing means comprising:
A. first input means adapted to input a first test amplitude voltage to a
first winding and a second sensing means adapted to sense second
amplitude with respect to said first test amplitude at said second
winding and a third sensing means adapted to sense third amplitude
with respect to said first test amplitude at said third winding;
B. second input means adapted to input a second test amplitude voltage
to a second winding and a first sensing means adapted to sense first

amplitude with respect to said second test amplitude at said first winding and a third sensing means adapted to sense third amplitude with respect to said second test amplitude at said third winding;
C. third input means adapted to input a third test amplitude voltage to a
third winding and a first sensing means adapted to sense first
amplitude with respect to said third test amplitude at said first winding
and a second sensing means adapted to sense second amplitude with
respect to said third test amplitude at said second winding;
D. third database means adapted to store each of said input test amplitude
voltages and said corresponding sensed amplitude voltages in a matrix
format;
E. second computation means adapted to compute test ratios of
amplitude Voltages according to pre-defined equations; and
F. fourth database means adapted to store each of said computed test
ratios;
3) comparator means adapted to compare each of said computed calibration ratios with each of said computed test ratios, correspondingly, to obtain a matched compared score and a mismatched compared score; and
4) location determination means adapted to determine location of partial discharge in relation to each of said windings and each of said compared values depending upon corresponding input amplitude test voltage relating to said mismatched compared score.
According to this invention, there is provided a system for detecting partial discharge location in transformers, having at least two windings and leads extending there through, said system comprises:
1) calibration means adapted to calibrate said system for testing, said calibration means including pulse input means for providing High

frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly, said calibration means comprising:
a) first input means adapted to input a first calibration amplitude voltage to a first winding and a second sensing means adapted to sense second amplitude with respect to said first calibration amplitude at said second winding;
b) second input means adapted to input a second calibration amplitude voltage to a second winding and a first sensing means adapted to sense first amplitude with respect to said second calibration amplitude at said first winding;
c) first database means adapted to store each of said input calibration amplitude voltages and said corresponding sensed amplitude voltages in a matrix format;
d) first computation means adapted to compute calibration ratios of amplitude voltages according to pre-defined equations; and
e) second database means adapted to store each of said computed calibration ratios;
2) testing means adapted to test said system for partial discharge, said testing means including pulse input means for providing High frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly, said testing means comprising:
A. first input means adapted to input a first test amplitude voltage to a first winding and a second sensing means adapted to sense second amplitude with respect to said first test amplitude at said second winding;

B. second input means adapted to input a second test amplitude voltage
to a second winding and a first sensing means adapted to sense first
amplitude with respect to said second test amplitude at said first
winding;
C. third database means adapted to store each of said input test amplitude
voltages and said corresponding sensed amplitude voltages in a matrix
format;
D. second computation means adapted to compute test ratios of
amplitude voltages according to pre-defined equations; and
E. fourth database means adapted to store each of said computed test
ratios;
3) comparator means adapted to compare each of said computed calibration ratios with each of said computed test ratios, correspondingly, to obtain a matched compared score and a mismatched compared score; and
4) location determination means adapted to determine location of partial discharge in relation to each of said windings and each of said compared values depending upon corresponding input amplitude test voltage relating to said mismatched compared score.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a schematic of a transformer with windings; and
Figure 2 illustrates a schematic of a transformer with windings and tap.
The invention will now be described in relation to the accompanying drawings, in which:

Figure 3 illustrates a system for detecting partial discharge location in transformers;
Figure 4 illustrates lumped parameter model of transformer winding;
Figure 5 illustrates a simplified high frequency model for transformer;
Figure 6 illustrates a calibration pulse;
Figure 7 illustrates PD pulse measurement when pulse injected to HV
Figures 8, 9, and 10 show the signal captured in HVE, LVN, HV-BT
respectively;
Figure 11 illustrates PD pulse measurement when pulse injected to LV; and
Figures 12, 13, and 14 shows the signal captured in HVE, LVN, HV-BT, respectively.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a schematic of a transformer (10) with windings (12) (LV
- Low Voltage and HV - High Voltage); and
Figure 2 illustrates a schematic of a transformer (10) with windings (12) (LV
- Low Voltage and HV - High Voltage) and tap.

The windings (12) are wound around a core (14) and immersed in oil (16). The oil serves as a dielectric medium. The windings (12), the core (14), and oil (16) are placed in a transformer housing (18).
Occurrence of PDs in electrical insulation is always associated with emission of several high frequency signals in the range of DC to several MHZ. During the PD generation there, PD can produce a number of signals at different locations within a large transformer including a discharge current in the neutral, a displacement current through the capacitive tapping of a bushing , pressure waves and ultra high frequency electromagnetic signal.
According to the prior art, Partial Discharge is detected by means of the following:
1) Acoustic emission Detection (AE Method) (is insensitive)
2) Electrical Detection - High Frequency Current Transformer (HFCT Method)
3) Electro Magnetic Detection - Ultra High Frequency Antennae (UHF Method) (is prone to noise)
PD activity in solid high voltage insulation induces small high frequency currents in the earth of the electrical system. These impulses travel along the equipment earth to the substation earth. Using a HFCT they can be detected as they pass through the CT. HFCT works on the principle of electromagnetic coupling. It is placed around the conductor to couple the pulse signals.
Acoustic detection, like electrical detection, focuses on the acquisition and recording of a signal generated by a partial discharge. However, instead of

capturing an electrical signal, acoustic PD detection endeavors to sense and record the acoustic signal created during a PD event. This signal is created because when the current streamer is formed within the void, the material around the hot streamer is vapourized. This vapourization causes and explosion of mechanical energy, which then propagates through the transformer tank in the form of a pressure field. The disadvantage of using the acoustic sensor is that in order to locate the complete geometry of the transformer is should be understood and complicated mathematic tool should be used for location. Secondly, when the pressure wave propagates through the oil medium, the signal may be attenuated due to the various structures present inside the transformer. Due this many attenuation mechanisms, received acoustic signals have very low intensity and so sensors must be very responsive to small changes in signal amplitude in order to detect a PD.
PD under oil are very fast electrical processes and radiate electromagnetic waves with frequencies up to the ultrahigh range (UHF: 300 - 3000 MHz). Electromagnetic waves are detectable with UHF probes inserted through oil valve provided in the tank. But the UHF method misses the possibility of a calibration because electro-magnetic UHF waves are attenuated by internal structures according to their travelling paths to the sensor. The UHF method also requires a pre-amplifier in order to increase the sensitivity and digital signal processing tool for discriminating the PD signals from other interferences.
Each of the above methods is prone to problems and is employed for purposes of detection of partial discharge. But, in these systems, there is always a need to know the geometry of construction of the windings, tap, and core with respect to the transformer housing. Since all large

transformers are designed according to client order and requirement, the geometry is dynamically variable and although a standard test can be employed for detection of partial discharge, its locations detection is not plausible.
According to an embodiment of this invention, there is provided a system (100) for detecting partial discharge location in transformers.
Figure 3 illustrates a system for detecting partial discharge location in transformers. Typically, these transformers have multiple windings and taps and leads extending from the windings. The leads are connected to High Frequency Current Transformer (HFCT - shown in Figures 1 and 2 of the accompanying drawings) through which HV calibration pulse is given.
An insulation fault in the transformer winding results in a PD current impulse injected into the winding at the position of the fault. This electrical signal then propagates along the winding before it reaches the two main terminals, i.e. the line and neutral ends. The electrical method for PD detection/location involves the use of appropriate sensors at the two winding ends to pick up the electrical signals. At the neutral end, HF current transformer can be used. At the line end, another HF current transformer clamped around the HV bushing tap or a capacitive coupler. By comparing the signals picked up at the two winding ends, it is then possible to locate the PD source.
Since PD generates high frequency signal, the transformer winding for the high frequency signal can be represented with equivalent circuit shown in the Figure 4 of the accompanying drawings.

The Impedance offered by the capacitance is less than the inductance so inductance can be neglected during the high frequency analysis.
In the higher frequency range, the capacitive ladder network applies. The ratio of the two terminal signal magnitudes can be used for location. This is called the capacitive ratio method or Amplitude ratio method. When PD is generated, the discharge current flows through the low impedance path which is offered by the capacitance for the high frequency signals. The equivalent circuit shown in Figure 4, of the accompanying drawings, can be simplified into a circuit which is shown in Figure 5 of the accompanying drawings.
Here, in Figure 5,
CC-L - Capacitance between core & Low voltage winding
CLV-HV • Capacitance between Low voltage & High voltage winding
CHv-Tank - Capacitance between High voltage winding & Tank
CLV - Low voltage winding capacitance
CHV - High voltage winding capacitance
CBT - Bushing tap capacitance
E - Earth
In accordance with an embodiment of this invention, there is provided a calibration means (30) adapted to calibrate the system for testing. The calibration means includes pulse input means for providing High Voltage pulse to the transformer windings and taps through the leads. The calibration pulses are input in a pre-determined format.

For the purposes of this invention, it can be assumed that the transformer to be tested has three windings; a first winding (HV - winding 1), a second winding (LV - winding 2), and a third winding (tap - winding 3).
A first pulse having a first calibration amplitude (voltage A) is given to the first winding (winding 1) by means of the first input means (32) and amplitudes at the second winding (winding 2) and the third winding (winding 3) are sensed as voltage A' and voltage A" respectively by means of second sensing means (35) and third sensing means (37) respectively.
Further, a second pulse having a second calibration amplitude (voltage B) is given to the second winding (winding 2) by means of the second input means (34) and amplitudes at the first winding (winding 1) and the third winding (winding 3) are sensed as voltage B' and voltage B" respectively by means of first sensing means (33) and third sensing means (37) respectively.
Still further, a third pulse having a third calibration amplitude (voltage C) is given to the third winding (winding 3) by means of the third input means (36) and amplitudes at the first winding (winding 1) and the second winding (winding 2) are sensed as voltage C and voltage C" respectively by means of first sensing means (33) and second sensing means (35) respectively..
In accordance with another embodiment of this invention, there is provided a first database means (38) adapted to store each of said calibration input pulse corresponding to each of said sensed pulse as below:

Winding 1 Winding 2 Winding 3
A A' A"
B' B B"
C' C" C
This is the calibrated amplitude matrix.
In accordance with another embodiment of this invention, there is provided a first computation means (40) adapted to compute ratios of amplitudes. Calibration ratios of A:A':A", B:B':B", and C:C':C" are computed.
In accordance with yet another embodiment of this invention, there is provided a second database means (42) adapted to store each of said computed calibration ratios.
In accordance with yet another embodiment of this invention, there is provided a testing means (50) adapted to test said system for partial discharge, said testing means including pulse input means for providing High Voltage pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly
The pulse input means is adapted to input pulse with a first amplitude (A) at a first winding, to input pulse with a second amplitude (B) at a second winding, to input pulse with a third amplitude (C) at a third winding.
In accordance with still another embodiment of this invention, there is provided a sensing means (first sensing means for first winding depicted by reference numeral 53, second sensing means for second winding depicted by

reference numeral 55, third sensing means for third winding depicted by reference numeral 57) adapted to sense: I. amplitudes at second winding (A') and third winding (A") when input
pulse with a first test amplitude (A) is given to first winding by means
of a first input means (52); II. amplitudes at first winding (B') and third winding (B") when input
pulse with a second test amplitude (B) is given to second winding by
means of a second input means (54); and III. amplitudes at first winding (C) and second winding (C") when input
pulse with a third test amplitude (C) is given to third winding by
means of a third input means (56).
In accordance with an additional embodiment of this invention, there is provided a third database means (58) for storing each of said input amplitudes (A, B, C) and each of said sensed amplitudes (A', A", B', B", C, C") in a matrix format as shown below:

Winding 1 Winding 2 Winding 3
PD1 A A' A"
PD2 B' B B"
PD3 C C" C
In accordance with yet an additional embodiment of this invention, there is provided a second computation means (60) adapted to compute test ratios of amplitudes such as A:A':A", B:B':B", and C:C':C".
In accordance with still an additional embodiment of this invention, there is provided a fourth database means (62) adapted to store each of said computed test ratios.

In accordance with another embodiment of this invention, there is provided a comparator means (70) adapted to compare each of said computed calibration ratios with each of said computed test ratios, correspondingly, to obtain a matched compared score and a mismatched compared score.
In accordance with another embodiment of this invention, there is provided a location determination means (80) adapted to determine location of partial discharge in relation to each of said windings and each of said compared values depending upon corresponding input amplitude test voltage relating to said mismatched compared score.
A, B and C are the injected amplitude of PD in mV/ mA and A' and A", B' and B" and C and C" are the measured mV / mA at the other windings simultaneously.
Since this HFCT sensors are of low cost, the total system becomes cheaper with only one sensor per winding and no complicated software or hardware.
Thus, detection and location (of Partial Discharge in a transformer) using this system, can be carried out.
In order to form the amplitude ratio matrix, calibration was carried for transformer using a standard PD calibrator which was used as per IEC -60270 shown in the Figure 6 of the accompanying drawings and discharge current measured through HFCT which is connected in LV Neutral (LVN), HV Earth (HVE) and HV Bushing Tap (HV-BT).
Figure 6 illustrates a calibration pulse.

According to a first non-limiting exemplary embodiment, PD pulse of 500 pC was injected across HV winding and measured through HFCT connected in LVN, HVE and HV-BT as shown in Figure 7 of the accompanying drawings
Figures 8, 9, and 10 show the signal captured in HVE, LVN, HV-BT respectively.
Table 1 shows PD pulse value at each terminal for 500 pC pulse injected in HV

S.NO HVE (mV) LVN (mV) HV-BT (mV)
1 187 26.5 90
Table 1
According to a second non-limiting exemplary embodiment, PD pulse of 500 pC was injected across LV winding and measured through HFCT connected in LVN, HVE and HV-BT as shown in Figure 11 of the accompanying drawings
Figures 12, 13, and 14 shows the signal captured in HVE, LVN, HV-BT. respectively. Table 2 shows the measured value through HFCt's in mV.
Table 2 shows PD pulse value at each terminal for 500 pC pulse injected in HV
Table 2

An amplitude matrix was formed with respect to the measured signal in each winding with the help of a PD calibrator. This system and method does not require any structure design information of transformer and complicated signal analysis to locate the PD inside the transformer. E.g. when the signal is injected in HV winding, then the measured signal at HVE earth is taken as reference and ratio for other two is taken with respect to that as shown in the table 3. The above system and method is also applicable for three winding transformers.
Table 3 illustrates an amplitude ratio matrix

HVE (mV) LVN(mV) HV-BT (mV)
PD in HV 1 0.14 0.48
PD in LV 0.16 1 0.11
Table 3
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1) A system for detecting partial discharge location in transformers,
having at least three windings and leads extending therethrough, said
system comprising:
i. calibration means adapted to calibrate said system for testing, said
calibration means including pulse input means for providing High
frequency pulse to each of said windings through said leads and
obtaining sensed inputs at each of the remainder of said windings
correspondingly;
ii. testing means adapted to test said system for partial discharge, said testing means including pulse input means for providing High frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly;
iii. comparator means adapted to compare each of said computed calibration ratios with each of said computed test ratios, correspondingly, to obtain a matched compared score and a mismatched compared score; and
iv. location determination means adapted to determine location of partial discharge in relation to each of said windings and each of said compared values depending upon corresponding input amplitude test voltage relating to said mismatched compared score.

2) A system as claimed in claim 1 wherein, said calibration means comprising:
a) first input means adapted to input a first calibration amplitude voltage to a first winding and a second sensing means adapted to sense second amplitude with respect to said first calibration amplitude at said second winding and a third sensing means adapted to sense third amplitude with respect to said first calibration amplitude at said third winding;
b) second input means adapted to input a second calibration amplitude voltage to a second winding and a first sensing means adapted to sense first amplitude with respect to said second calibration amplitude at said first winding and a third sensing means adapted to sense third amplitude with respect to said second calibration amplitude at said third winding;
c) third input means adapted to input a third calibration amplitude voltage to a third winding and a first sensing means adapted to sense first amplitude with respect to said third calibration amplitude at said first winding and a second sensing means adapted to sense second amplitude with respect to said third calibration amplitude at said second winding;
d) first database means adapted to store each of said input calibration amplitude voltages and said corresponding sensed amplitude voltages in a matrix format;
e) first computation means adapted to compute calibration ratios of amplitude voltages according to pre-defined equations; and
f) second database means adapted to store each of said computed calibration ratios.

3) A system as claimed in claim 1 wherein, said testing means comprising:
A. first input means adapted to input a first test amplitude voltage to a
first winding and a second sensing means adapted to sense second
amplitude with respect to said first test amplitude at said second
winding and a third sensing means adapted to sense third
amplitude with respect to said first test amplitude at said third
winding;
B. second input means adapted to input a second test amplitude
voltage to a second winding and a first sensing means adapted to
sense first amplitude with respect to said second test amplitude at
said first winding and a third sensing means adapted to sense third
amplitude with respect to said second test amplitude at said third
winding;
C. third input means adapted to input a third test amplitude voltage to
a third winding and a first sensing means adapted to sense first
amplitude with respect to said third test amplitude at said first
winding and a second sensing means adapted to sense second
amplitude with respect to said third test amplitude at said second
winding;
D. third database means adapted to store each of said input test
amplitude voltages and said corresponding sensed amplitude
voltages in a matrix format;
E. second computation means adapted to compute test ratios of
amplitude voltages according to pre-defined equations; and
F. fourth database means adapted to store each of said computed test
ratios.

4) A system for detecting partial discharge location in transformers,
having at least two windings and leads extending there through, said
system comprising:
i. calibration means adapted to calibrate said system for testing, said calibration means including pulse input means for providing High frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly; ii. testing means adapted to test said system for partial discharge, said testing means including pulse input means for providing High frequency pulse to each of said windings through said leads and obtaining sensed inputs at each of the remainder of said windings correspondingly;
iii. comparator means adapted to compare each of said computed calibration ratios with each of said computed test ratios, correspondingly, to obtain a matched compared score and a mismatched compared score; and
iv. location determination means adapted to determine location of partial discharge in relation to each of said windings and each of said compared values depending upon corresponding input amplitude test voltage relating to said mismatched compared score.
5) A system as claimed in claim 3 wherein, said calibration means
comprising:
a) first input means adapted to input a first calibration amplitude voltage to a first winding and a second sensing means adapted to sense second amplitude with respect to said first calibration amplitude at said second winding;

b) second input means adapted to input a second calibration amplitude voltage to a second winding and a first sensing means adapted to sense first amplitude with respect to said second calibration amplitude at said first winding;
c) first database means adapted to store each of said input calibration amplitude voltages and said corresponding sensed amplitude voltages in a matrix format;
d) first computation means adapted to compute calibration ratios of amplitude voltages according to pre-defined equations; and
e) second database means adapted to store each of said computed calibration ratios.
6) A system as claimed in claim 3 wherein, said testing means comprising:
A. first input means adapted to input a first test amplitude voltage to a
first winding and a second sensing means adapted to sense second
amplitude with respect to said first test amplitude at said second
winding;
B. second input means adapted to input a second test amplitude
voltage to a second winding and a first sensing means adapted to
sense first amplitude with respect to said second test amplitude at
said first winding;
C. third database means adapted to store each of said input test
amplitude voltages and said corresponding sensed amplitude
voltages in a matrix format;
D. second computation means adapted to compute test ratios of
amplitude voltages according to pre-defined equations; and

E. fourth database means adapted to store each of said computed test ratios.