Volume 32 No. 3July - September 2015

1. ERDA’s Laboratories for Evaluation of

Insulating Materials: A Capability

Profile

ERDA has state-of-the-art laboratories forcertification evaluation of liquid and solidinsulating materials used by the electricalengineering industry. The liquid dielectricslaboratory undertakes evaluation of mineral andsynthetic oils used in electrical products such astransformers. Evaluation of new as well as in-service oils is undertaken. Facilities are alsoavailable for evaluation of lubricating oils. The soliddielectrics laboratory is engaged in evaluation ofsolid insulating materials such as papers,pressboards, laminates, rubbers, etc. Bothlaboratories have been providing services to utilitiesand industries for over four decades.

ERDA’s NABL accredited Liquid DielectricsLaboratory has state-of-the-art equipment forevaluation of transformer, capacitor, & lubricatingoils. The laboratory is also equipped to undertakeevaluation of natural and synthetic ester based oilsas per various national and international standards.Sophisticated diagnostics and evaluation equipmentavailable with this laboratory include automated gaschromatographs with headspace system, HPLC forFuran analysis, flash point apparatus, interfacialtensiometer, rotating bomb oxidation stability setup(RBOs), resistivity and tan delta bridge, etc. Thelaboratory is also equipped with specializedanalytical test facilities such as FTIR spectrometerfor PNA analysis and detection of presence ofoxidation inhibitors along with a sophisticated gaschromatograph for identification of PCBs in oil.

The laboratory has nearly thirty ongoing ratecontracts of oil evaluation with generation,transmission and distribution companies as well asvarious process sector industries such as cement,petrochemicals, etc. The laboratory evaluates morethan 10,000 oil samples every year. This translatesinto condition assessment of more than 8,000 powertransformers every year.

The laboratory provides consultancy in liquiddielectrics and also undertakes R&D projects

1.1.1 Introduction

1.1 Liquid Dielectrics Laboratory

Con

tents

Pg. No.

1.0 ERDA’s Laboratories for Evaluation of Insulating Materials: A Capability Profile

2.0 Major Business Contract and Empanelments Received

3.0 Letters of Appreciation

4.0 Customer Meetings

5.0 Research & Development

6.0 Important Visitors and Industrial Visits

7.0 Invited Lectures at ERDA

8.0 Training Programs Conducted / Planned

9.0 Health & Happiness Program by Art of Living

10.0 Technical Articles

11.0 Inspiring Leader: Dr. M. Visvesvaraya ... 12

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... 05

... 06

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related to liquid dielectric insulation systems. MajorR&D projects successfully executed includedevelopment of an online evolved hydrogen gassensor for rapid fault detection in transformers.This pioneering and innovative invention has wonmany national & international awards and has beensuccessfully technology - transferred to a majortransformer manufacturer in the USA.

To facilitate decentralized and quick access to itscustomers in different regions of the country, the

Gas Chromatograph (GC)

Tensio Meter

02

laboratory has established NABL accreditedfacilities for oil evaluation at Rabale, Navi Mumbai(ERDA-West), Rajahmundry (ERDA-South), &Sonepat (ERDA-North). The laboratory is alsoequipped with a mobile van for undertakingtransformer oil evaluation at site. The laboratoryprovides regular services for collection oftransformer oil samples from in-servicetransformers at customer’s site.

With it highly qualified, skilled and experiencedmanpower along with its state-of-the artinfrastructure with outreach centers spread all overthe nation, combined with the massive scale of itsoperations, the laboratory has emerged over theyears as the number one laboratory of choice of theIndian utilities and industries.

1.1.2 Certification Evaluation & Testing Capability

• Dissolved GasAnalysis [IS:10593-2006]

• PNA Analysis [IS: 13155-1991)

• Furan Analysis [IEC:61198-1993]

• Oxidative Inhibitor Content [IS:13631]

• Moisture Content Determination in PaperInsulation

• Degree of Polymerization of Paper used in OilFilled Transformers

1.1.2.1 Evaluation of Used Mineral Oil Filled inTransformer [as per IS & IEC]

1.1.2.2 Evaluation of New Transformer Oil[as per IS & IEC]

1.1.2.3 Specialized Evaluation Services:

1.1.2.4 Services Provided Through Mobile TestLaboratory for Oil Evaluation at CustomerDoorstep and through Site Laboratories[ERDA (West) – Navi Mumbai, ERDA (North)

– Sonepat and ERDA(South) – Rajahmundry]

High Performance Liquid Chromatograph

View of Mobile Van

Resistivity & Tan Delta Testing in Mobile Van

Moisture Content Determination & Dissolved Gas Analysisin Progress in Mobile Van

The mobile test laboratory and the site laboratoriesare equipped with facilities for following NABLaccredited transformer oil tests:

• Electric Strength (BDV)

• Water Content

• Resistivity

• Tan Delta

• Dissolved GasAnalysis

• Flash Point

• Acidity

• Sludge

• Inter Facial Tension

03

• In-service, oil testing capability

• Density (only available at site laboratories)

• FuranAnalysis

(only available at ERDA(West) laboratory)

• Development of Demonstration Model ofTransformer Oil Reconditioning Plant for RuralAreas

• Residual Life Assessment of Power Transformerby Laboratory Simulation

• Development of Online Evolved Hydrogen GasSensor for Transformer Fault Detection

• Development of Prototype Thermosyphon forPower Transformer

• Field Trial of Thermosyphon in PowerTransformers in GEB Grid

• Development of Natural Ester basedTransformer Oil

• Evaluation of Synthetic Ester Oils

• Failure Investigations of Oil Filled Equipment

The solid dielectrics & polymers laboratory has anarray of sophisticated facilities & instrumentationfor certification testing & characterization of a largeclass of dielectric & polymeric materials in variousforms and shapes, as per national and internationalstandards. These state-of-the-art facilities includeinstrumentation for characterization/identificationof rubbers & plastics, determination of glasstransition (Tg) and melting point (Tm) of polymersas well as measurement of degree of polymerization.

A subset of the solid dielectric & polymericmaterials routinely evaluated as per National /International standards include:

• Papers

• Press Phan Papers

• Press Boards and Pre Compressed Boards

• Laminates

• Cable Jointing Compounds

• Adhesive Tapes

• Non-Ignitable Boards

1.1.3 Major Research & Development ProjectsSuccessfully Executed

1.2.1 Introduction:

1.2.2 Products / Materials Evaluated:

1.2 Solid Dielectrics Laboratory

• Plastics

• B-Stage Epoxy Glass Cloths

• Molding Materials

• Varnishes

• Resins

• Combined Flexible Insulation Sheets

• Fiber-Glass Reinforced Laminates

• Rubberized Cork Sheets

• PGAM Tape / Semica Therm Tapes

• Rubber / Fiberglass Sleeves

• Poly Propylene Films

• FiremanAxe, Multi Edge RescueAxe

• SMCs/DMCs

• Cable Truncking

• Piercing Connectors

• Dead-end Clamps

• Rubbers

• Insulating Sleeves

• Cable Filling Compound/Cable Outer Sheath forOxidative Induction Time (OIT)

• Security Seals

• UV Exposure

• ClimaticAgeing

• Tensile Strength

• Flexural Strength

• Heat Deflection

• Impact Strength

• Volume Resistivity

• Surface Resistivity

• Dielectric Strength

• Dissipation Factor and Dielectric Constant

• Conductivity and pH of Aq. Extract for KraftPaper / Press board

• Air Permeability

• Degree of Polymerization

• ThermalAnalysis by TGA/DSC

• To facilitate the Indian industry in meeting ROHsregulations while exporting electro technical

1.2.3 Some Major Evaluation Tests Undertaken atSolid Dielectrics Laboratory:

1.2.4 Specialized Evaluation Tests:

04

items to the European Union, the solid dielectrics& polymers group at ERDA has set up alaboratory for certification testing for ROHscompliance as per the framework of IEC 62321.The compliance testing against this standard canbe conducted at two levels at ERDA. At level-I,an Innov-X Systems make X-Ray FluorescenceSpectrometer (XFS), is used for rapid screeningfor Pb, Hg, Cd, Cr, & Br (300 ppm cap). Formore precise quantification of the five hazardouselemental species, capability exists for the nextlevel-II tests using a state-of-the-art PerkinElmer make Atomic Absorption Spectroscopy(AAS)

• ERDA also has capability for facilitating precisequantification of hexavalent Chromium ions(Cr+6) as well as Poly-Brominated Biphenyls(PBBs) and Poly-Brominated Diphenyl Ethers(PBDEs), as per the requirements and guidelinesof IEC 62321

• Specialized test services such as ESDD/NSDDbased measurements for pollution levels oninsulators

• Optical emission spectroscopy based chemicalanalysis of MS, SS, & Cu (IS 228/IS 440).

1.2.5 Major EquipmentAvailable with the Laboratory

X-Ray Fluorescence Spectrometer (XRF)

Optical Emission Spectrometer

UV - Accelerated Ageing - Weathering Test Chamber

Fourier Transform Infrared Spectrometer

High Performance Liquid ChromatographAtomic Absorption Spectrometer (AAS)

05

2.0 Major Business Contracts and

Empanelments Received

2.1 Empanelment with NTPC

2.2 Power Quality Measurement as per CEAGuidelines:

ERDA has been empanelled as an agency forcarrying out energy audit and performanceassessment by NTPC for 3 years. This empanelmentwill enable ERDA to grow rapidly in the area ofperformance efficiency assessment of thermalgenerating stations.

ERDA received offer from Powerica Ltd forcarrying out power quality measurement at the pointof common coupling (PCC) where, 20 MW windgenerat ing sta t ion of Powerica Ltd isinterconnecting with 66 kV grid of GETCO. Thework involved measurement of mandatoryparameters (as per CEA guidelines) such as voltageand current harmonic content, DC injection andflicker for wind power plants. The measurementswere carried out for a continuous period of 24 hours.

The recorded data included frequency, current,voltage, active power, reactive power, apparentpower, power factor, current TDD, voltage THD,short term flicker, long term flicker and DC currentinjected from wind generating station to grid.

Comparative Tracking Index (CTI) TesterUniversal Testing machine (UTM)

Fig. 1. Temperature Contour

The captured data, voltage and current waveformswere analyzed up to 25th order harmonics using FastFourier Transform (FFT) algorithm and current totaldemand distortion (TDD) and voltage totalharmonic distortion (THD) were calculated. Usingthe FFT algorithm, DC component in current wasextracted from harmonic data and compared withlimits as per CEA guidelines. Calculated voltageTHD and current TDD were compared with limitsgiven in CBIP publication no. 251-1996 and IEEE519:2014 respectively. Flicker limits werecompared with limits mentioned in IEC 61000-3-7

The measurements were carried out in presence ofofficers from Powerica Ltd and GETCO. Detailedr e p o r t w i t h d e t a i l e d c o n c l u s i o n s a n drecommendations was submitted to Powerica.

As part of a residual life assessment contract fromGSECL, ERDA undertook detailed numericalsimulation of a 210 MW BHELKWU design turbinerotor with the objective of predicting its remnant lifewith respect to the degradation mechanisms of creepand low cycle fatigue. This work was undertaken byconducting coupled structural and thermal analysisin steady state and transient solution modes. Typicalresults obtained are shown in Figs.1 and 2, below:

2.3 Residual LifeAssessment of Turbine Rotor

06

The edited extracts of a letter of appreciationreceived from an esteemed customer is presentedbelow:

“………..We wish to thank you for the courtesyextended to our engineer and got the test conductedon top priority in spite of your busy schedule. Thisgesture will go a long way in the professionalrelation of ERDA and us. Our special thanks to theengineers of Short Circuit, Impulse and HighVoltage Laboratory. We really appreciate the promptservice provided by ERDAStaff………..”

3.1

3.0 Letters of Appreciations

4.0 Customer Meetings4.1 Delhi Metro Rail Corporation (DMRC)

4.2 Gujarat State Electricity Corporation Limited(GSECL)

“Presentation on ERDA Capabilities” wasorganized at DMRC, “Metro Bhawan”, New Delhion 26th August 2015. Key speakers from ERDAwere Mr. Nilesh Pandya on Cables, Mrs. SangeetaGodkhindi on Insulator Testing and a GeneralPresentation by Shri Rajat Varshney. A Total of 17Officials of DMRC including Director Mr. A.K.Garg & Two Executive Directors Mr. A.K. Singh &Mr.A.K. Sharma attended the presentation.

A one day program on Performance EfficiencyTesting & Condition Monitoring of Thermal Power

A View of the Customer Meet Program at GSECL, Wanakbori

Plants was organized on 10th August 2015 forGSECLofficers at Wanakbori Thermal Power Plant.A total of 61 engineers from their various powerstations attended the program.

ERDA organized an “Interactive Session” atTANGEDCO Headquarters on 20th August topresent its credentials and capabilities to theofficials of TNEB Ltd., as a part of its marketingplan.

The program began with a show of various videosfollowed by general presentation. Thereafter,technical presentations pertaining to testing oftransformers, CT/PTs, energy meters, EMI / EMC,T&D hardware, reliability studies, cables as well ascondition monitoring of electrical products weremade by senior officers of ERDA.

In all, 38 engineers from the Generation,Transmission and the Distribution sectors of TNEBattended the meeting. They found the session veryuseful and informative.

The participants inquired specifically aboutharmonics measurement, specifications for themobile van apart from active participation duringthe presentations. Dr. P. A. Krishnamoorthy, Dy.Director and Shri K. V. Annadhurai coordinated theevent.

4.3 Interactive Session at TANGEDCO, Chennai

Fig. 2. Equivalent Stress Contour

A View of the Interactive Session at TANGEDCO, Chennai

07

1. Energy Efficiency Improvement ofMotorized Fluid Handling Machinery:Case Studies

2 Design and Development of PilotMicrogrid System & Test andCertification

3 Importance of Testing andConformance in LED Manufacturing

4 Energy Efficient Motors & Pumps

5 Cables – Flammability Evaluation

6 Solar Cables for Photovoltaic Systems

7 Industrial Pumping Systems:Fundamentals and EnergyConservations

B. Vasiyani andG.S. Grewal

Asheesh Dhaneria,Satish Chetwani,Gautam Brahmbhatt

Gautam Brahmbhatt,Nitin Patel,Vinod Gupta

R.P.Singh,Satish Chetwani,Gautam Brahmbhatt,Vinod Gupta

Nilesh Pandya

Nilesh Pandya,Sheetal Panchal,Jay Purohit

G.S. Grewal

Electrical India, Vol. 55; No.7; July 2015;p.66-70

Conference on Solar Power Development(Including Roof Top Solar Systems) andIssues for its Grid Connectivity, organizedjointly by CBIPand CIGRE India on 30-31July 2015 at New Delhi

Conference on 'Make in India: BrightProspects of LED Manufacturing'organized by PHD Chamber, Delhion 14th August 2015

Seminar on 'Standardized Pumps ForEnergy Conservation’ organized by BISAhmedabad on 03rd September 2015

IEEMA Journal, Vol.7, Issue No.1,September 2015, p. 58-62

Electrical India, Vol.55, No.9, September2015; p. 52-54

Invited talk delivered at Essar LearningCentre, Essar Steel Ltd., Hazira, 18thSeptember 2015 as a part of Engineers DayCelebrations

Sr. Title Authors Name of the Journal / Conference

5.0 Research & Development

5.1 Papers Published / Presented / Invited Talks Delivered

5.2 Completed R&D Project: Development of 2.2kWIE4 Motor

Electric motors used for industrial applicationsconsume 60-65% of the generated electrical energyworldwide. Electric motor systems are, by far, themost important type of load in industry, accountingfor approximately 70% of industrial electricity. Inthe tertiary sector (non-residential buildings),although not so relevant, electric motor systems useabout one third of the consumed electricity. In orderto promote a competitive motor markettransformation, a new international standard, theIEC 60034-30 has been approved. This standardglobally harmonizes motor energy-efficiencyclasses in general-purpose, line-fed, three-phase,squirrel-cage, induction motors (IMs). In thisstandard, four efficiency classes are proposed,namely Standard Efficiency (IE1), High-Efficiency(IE2), Premium Efficiency (IE3) and Super-Premium Efficiency (IE4). IE1, IE2 and IE3 classes

are normative, but IE4 class is intended to be onlyinformative, since sufficient market andtechnological information is not available to allowIE4 standardization.

In order to help electrical motor manufacturers todevelop indigenous technologies for IE4 classmotor, ERDA has taken up an internal R&D projectto develop an IE4 class motor.

ERDAhas developed an IE4 class efficiency, 2.2kWcommon 3 Φ squirrel cage machine, which is easy tomanufacture and does not use costly permanent

ElectromagneticAnalysis of Motor

CFD Analysisfor Fan Design

08

magnets. This development was possible throughdesign optimization carried out using CFD and FEAbased electromagnetic analysis for stator, rotor,winding and the fan.

The developed motor was tested at ERDAand foundto have efficiency of 90.73%, with a ower factor of0.748 and a temperature rise of 29˚C. The samemotor can also be classified under dual rating of2.2kW IE4 and 3.7 kW IE3 in the same frame as perthe test results achieved.

p

Acase of failure of a water-wall boiler tube of a coal-based thermal power plant was received for failureanalysis study. The failed tube had a rupture parallelto the longitudinal axis of tube with a shape of a“fish-mouth” caused due to internal hoop-stressassisted fracture. The rupture lips showed extreme

5.3.1 The Evidence:

5.3 Failure Investigation of Power Plant Tubing

Developed 2.2kW IE4 Class Motor

thinning. The external surface of tube wall at-and-near rupture indicated erosion caused due to fluidimpingement. The tube wall also showed reductionin thickness from external side (outer surface) at andnear rupture, on the fire-side of tube (Fig.1). Thechemical composition analysis of the tube materialconfirmed that it was a plain carbon steel of gradeSA 210 Gr. A1 as per design specification.Metallographic examination indicated that the tube-material was in normalized (heat-treatment)condition, as per requirement. No degradation withrespect to high-temperature or creep degradationwas observed, (Fig. 2). Hardness measured on thecut samples at various locations was 148 HV, whichis as per requirement (HV165 HV max) of thestandard.

The evidence of wall thinning along with theerosion-corrosion type topography of the tubesurface at & near rupture suggested the failuremechanism to be erosion corrosion driven wallthickness reduction, eventually leading to unstablecrack propagation. As the tube is located in thevicinity of the soot-blower, impacting steam flowconditions due to malfunctioning of soot blower ledto rapid erosion corrosion with eventual failureunder excessive hoop stress.As a remedial measure,it was suggested to ensure adequate alarming andinter locking circuitry in the soot blower system toenable undertaking of timely corrective action.

5.3.2 The Conclusions

Fig. 1: Ruptured water-wall tube in as-received condition shows opening-up of tube due to rupture (1),

and erosion of tube surface at & near crack-tips (2) & (3)

Fig.2: Micrograph shows ferrite (bright) and pearlite (dark)

phases indicating normalized (heat-treatment) condition.

No degradation with respect to creep was observed

09

6.0 Important Visitors and Industrial Visits

6.1 A team, comprising of Shri S. Sumanth, Director(Transmission), Shri M. S. Prabhakar, Suptg.Engineer (T&P) and in charge Chief Engineer(T&P), Shri Renuprasad, Executive Asst to Director(Transmission) and Shri Ananthashayana Iyengar,Executive Engineer from Karnataka PowerTransmission Co. Ltd., (KPTCL), Bengaluru visitedERDAon 31st July 2015.

6.2 A team of Senior Executives from BESCOM,Bengaluru visited ERDAon 4th & 5thAugust 2015.The team comprised of Mrs. G. Sheela, GeneralManager (QS&S), Mr. H. Narayana Naik, Chief

Engineer (T&P), Retired from KPTCL, Mr. B. R.Somashekar, Dy. General Manager and Shri T.Raghu,Asst. General Manager

Bangladesh Rural Electrification Board (BREB)officials, Mr. Md. Yeakub Ali Patwary, Jt. Secretaryand Mr. Md. Mostafa Kamal, Project Directorvisited ERDAon 4th September 2015.

6.3

6.4 Seven Senior Officers from Reliance IndustriesLimited., Mumbai and Vadodara, Dr. Ajit Sapre, Dr.Rakshvir Jasra, Dr. Sanjeev Katpi, Dr. PradipMunshi, Mr. Ninad Ingle, Mr. Jayesh Vora, and Mr.Gordhan Goyal visited ERDA on 4th September2015.

6.5 Industrial Visits

Final year Electrical Engineering students from seven engineering colleges [total number of 420 students] havemade industrial visits to ERDA. In July – September, 2015.

A view of Engineering Students at our Campus during Industrial Visit

10

7.0 Invited Lectures at ERDA

Mr. Amelendu Mohanty, Technical Advisor, TBEA delivered a lecture on Power Transformers on 23rd July 2015at Chemburkar Learning Centre. Fifty nine ERDA staff members participated in the lecture. This highlyinformative and interactive lecture was widely appreciated by the participants.

A view of Mr. Amelendu Mohanty, Technical Advisor, TBEA Delivering his Lecture

8.0 Training Programs Conducted / Planned

9.0 Health and Awareness Workshop by NGO - “Art of Living”

8.1

8.2

8.3 Training Course Planned

A two day training on Design Aspects & Performance Evaluation of Motors & Pumps was conducted on 6-7August 2015. Alarge number of participants from utilities and industries participated in the program

A special program on Evaluation of Cables & Accessories, was conducted for RITES Ltd., Mumbai on 25-26September 2015 at our premises.

1. High Voltage Evaluation Techniques 8-9 October

2. Foundation Course of Smart Grid [Jointly with India Smart Grid Forum (ISGF)] 15-17 October

3. EMI/EMC Evaluation Techniques for Electronic Equipment & Machinery 16-17 October

4. Uncertainty Measurement in Electrical Discipline 27-28 November

5. Condition Monitoring of Motors, Generators, Pumps & Turbines 3-4 November

6. Industrial Energy Management Techniques 16-17 December

ERDA organized a “Health and Happiness” workshop from 7th - 11th September 2015. A total of 25 ERDAemployees participated in the workshop. This workshop is specially designed for corporates by “Art of Living”,the biggest NGO in the world, and has proved to be the best solution for Stress Management. The workshopincludes various yoga exercises such as ‘Sudarshan Kriya’, Asanaas, Meditation etc. The workshop wasconducted by well-known yoga trainer Dr. M. Makkar. The workshop has been deeply appreciated by allparticipants and many employees have requested for a second batch.

A view of the Asanaas being Performed during the Workshop Workshop Participants with Yoga Trainer, Dr. M Makkar

11

10.0 Technical Articles: Dissolved GasAnalysis for New Transformers

10.1 Introduction

10.2 New Transformers

10.3 Before &After Heat Run Tests

The trouble free performance of a transformerduring its service life is of paramount importance inpower stations to ensure uninterrupted andeconomic power supply of transformers whichoperate under complex environmental conditionsand variable thermal and electrical stresses duringservice. As a result of normal ageing process,insulating oil breaks down and produces gases likehydrocarbons, hydrogen and carbon oxides whichdissolve in oil. The rate of generation and presenceof some combustible gases in large quantitiesdefinitely indicate some internal fault in incipientstage and if not monitored regularly, even at anadvanced stage. Therefore, it is advisable to detectthe faults in its early stage, so that the developmentof major faults with consequent damage to atransformer can be avoided.

Analysis of dissolved gases has been a proventechnique in use for the last 2-3 decades formonitoring the health of a transformer in service bysensing incipient fault well in advance before, eventhe Buchholz relay operates. Moreover, the latesttrend is also to conduct DGAas a special test on newtransformers at manufacturer’s end, before and afterthe heat run test.

DGA may be carried out on oil immediately afterfilling the transformer, prior to starting the heat runtest, followed by the next DGA, approximately 2 &24 hours after the termination of heat run test at themanufacturers’ works. However, during the test,additional oil samples may be taken at intervals ofabout 4 hours each, if required.

At site, the analysis may be carried out on new oilafter filling in the transformer and before charging.This forms the initial bench mark for thetransformer for trend monitoring in service. Theanalysis may be repeated after three months ofservice to ensure that no abnormality is indicatedduring the initial period of operation of newtransformer after commissioning.

The existing methods of interpreting DGA resultsare not applicable for new transformer, oil as beforethe test, there may initially be small amount of gasesdissolved in the oil, the source of which may begases formed during the refining processes and not

completely removed from the oil by degassing &gases formed during drying and impregnating thetransformer in the factory. Furthermore, duration oftest is short and only small amount of gas isgenerated.

Therefore, for the interpretation of DGA resultsbefore & after heat run tests, a guideline has beensuggested by CIGRE working group. Table-1indicates the maximum values of gases which canbe dissolved in the oil of new transformer beforeheat run test. The interpretation method after heatrun test is based on the rate of increase of particulargases and fixed permissible limits. It is alsosuggested to ensure that the detection sensitivity ofequipment should be consistent with the actualconcentration levels to be measured with thechanges which yield significant information. Thesmallest detectable quantity (Sd) of the individualgases is also given in Table-1.

Gas Concentration of Minimum Detectable Value‘Sd’ and Maximum Permissible Value of Gases‘(X)1’in Oil

Sl. No. Gas Sd (X)1(ppm) (v/v) (ppm) (v/v)

1 CO 10.0 200.0

2 CO 5.0 80.0

3 H 2.0 15.0

4 CH 0.1 2.5

5 C H 0.1 2.0

6 C H 0.1 2.0

7 C H 0.1 1.0

To decide the permissible changes of individualgases during heat run test, the “maximum analyticalspread (Sa)” should be evaluated as follows, for anygas (say X);

Sa(X) = 0.1 (X)1+ 2 Sd (X)

Where, X1 = Original quantity of gas X

Sd = Smallest detectable quantity

If the difference in concentration of any gas beforeand after heat run test is less than ‘Sa’ of the gas,transformer is healthy and no further interpretationis required. Otherwise, resource has to be taken toStage-IIAnalysis.

If all the criteria in range1 given in Table – II arefulfilled by DGA result it can be concluded that the

10.3.1Stage – I: Analysis

Table-1

10.3.2 Stage – II: Analysis

2

2

4

2 6

2 4

2 2

Edited & Published by Dr. G. S. Grewal for Electrical Research & Development Association,

Registered Office & ERDA (West) Laboratory : R-336, TTC Industrial Area, Thane - Belapur Road,

MIDC, Rabale, Navi Mumbai - 400 701

ERDA Laboratory Complex, ERDA Road, Makarpura Industrial Estate, Vadodara - 390 010

e-mail: gurpreet.grewal@erda.org, erda@erda.org, website : http//:www.erda.org

Printed by : Multiprints - 0265-2285592 (M) 9825034026

Tel. +91(0265) 3043128-31, 3048044, 2642942, 2642964, 2642377, Fax: +91 (0265) 2638382,

Toll Free No. : 1800 233 2668,

ELECTRICAL RESEARCH AND DEVELOPMENT ASSOCIATION(Accredited by the National Accreditation Board for Testing and Calibration Laboratories, Govt. of India)

ERDA Road, GIDC, Makarpura, Vadodara - 390 010

transformer has no thermal fault. However, if one ormore criteria exceed the range 1 limits and all thecriteria lie below the range 2 limits, there is apossibility of a fault caused by load current and/orleakage flux. In such cases, oil during service shallbe closely monitored by DGA.

If one or more of the limits of range 2 are exceeded,more oil samples taken during heat run test shall beanalyzed to obtain more information for which, anarrangement between purchaser and manufactureris required.

12

Table - 2No. Criteria Range 1 Range 2

1. (C H )2 – (C H )1

2. 1/t{[(H )2–(H )1]+[(CH )2–(CH )1]

+[(C H )2 – (C H )1] +[(C H )2 –

(C H )1]}

3. 1/t [(CO)2 – (CO)1]

4. 1/t [(CO )2 – (CO )1]

5. (C H )2 – (C H )1

(C H )2 – (C H )1

Here t is duration of heat run test in hours, (X)2 and (X)1 are concentrations ofgas X, after and before the test.

5 criteria may only be used if increase in gas concentration of C H &C H

before and after heat run test are > 10 Sa

2 2 2 2

2 2 4 4

2 4 2 4 2 6

2 6

2 2

2 4 2 4

2 6 2 6

2 4 2 6

<Sa(C H ) <Sa(C H )

<2 ppm (v/v)/hr <5 ppm(v/v)/hr

<5 ppm (v/v)/ hr < 25 ppm(v/v)/hr

< 20 ppm (v/v)/hr < 100 ppm(v/v)/hr

< 1 ppm (v/v)/hr < 3 ppm (v/v)/hr

2 2 2 2

th

11.0 Inspiring Leader: Dr. M. Visvesvaraya

Dr. M. Visvesvaraya was born on the 15 of September 1861.All through his student days he worked hardand in a systematic way. He was an early riser and started his work quite early. When he was twenty, hejoined the Science College in Poona to study Engineering. Three years later, by sheer determination andhard work he ranked first in the L.C.E. and the EC.E. Examinations. He started his career as AssistantEngineer at Nasik for Government of Bombay. From Bombay, Visvesvaraya went to Hyderabad as ChiefEngineer. Here he achieved something that was simply impossible at that time. The river Moosa dividedthe city of Hyderabad into two. When rains lashed, the river was in floods and the waters of the river pouredinto many houses, and men and cattle were carried away. Visvesvaraya planned dams to tame the Moosaand also suggested that parks should be laid out on the banks of the river.

His resourcefulness earned him the position of a Chief Engineer in Mysore State. Visvesvaraya continuedto be the Chief Engineer of Mysore for three years. In 1912 when he was 51, the Maharaja of Mysore chose Visvesvaraya as his Dewan.

Visvesvaraya realized that industry was the backbone of a country. So he developed the existing industries. He also got experts fromother countries to help by teaching their skills. Thus many new industries came up during his chief minister ship. He started theSandal Oil Factory, the Soap Factory, the Metals Factory, the Chrome Tanning Factory and Bhadravati Iron and Steel Works. He wasalso the key in the opening of the Bank of Mysore. He also brought in many hotels into Mysore and played a major role in the layingof railway lines. Visvesvaraya did in six years what many others could not have accomplished in sixty years. In 1955 when he was94 years of age, Visvesvaraya was honored and made a 'Bharat Ratna' or the Gem of India. Even at that age he was so particular abouthis dressing that people who went to see him were surprised for he was so neat and tidy.His memory even when he was almost ahundred years old remained pristine. Fifty years after he had tamed river Moosa, at the age of 97, there was a discussion about theriver with certain others where some references were made to some intricate details. Visvesvaraya called a helper and, pointing to abookshelf, said, "Bring the three or four books in the middle of the third row." Then he opened one of them and pointed exactly to thedetail under discussion on that page.

Visvesvaraya silently passed away on 14th of April 1962. He was 101. Visvesvaraya led the country to the path of progress, everyone of his creations was considered mighty and magnificent. But far mightier and far more magnificent was the matchless dreamer,doer and leader who paved the way to modern India. In his honour, his birthday is celebrated all over the country as Engineers Day.

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