News letter - 31-12-2013 - ERDA News 1.2 Major Infrastructure 1.3 Some Major Facilities ...Relay,...

1. Switchgear Testing: State-of-the Art Laboratory 2at ERDA

2. ERDA's Environmental Corrosion Facility: 6The Salt Spray Test

3. Employee Welfare Activities 8

4. Customer Service Orientation Training 8

5. Important Visitors 9

6. Seminar on Total Power Quality Management 10

7. Training Courses Conducted 10

8. Open House 2013 10

9. Customer Feedback: Extract from Apprecation Letter 11

10. Diwali Celebrations 11

11. Technical Article: Environmentally Friendly WO 112

Doped Ag-SnO Contacts Prepared 2

by Powders Processed through Electro-chemical Route

12. Thomas Alva Edison 15

CONTENTS

Electrical Research & Development Association

ERDA News

Vol. 30 No. 4 October - December 2013

"ERDA Wishes Happy New Year 2014,to all its Valued Readers"

Electrical Research & Development Association2

ERDA News

1.2 Major Infrastructure

1.3 Some Major Facilities

1.3.1 20kA 3Ø Stabilized High Current Source

1.3.1.1 Major Tests

1.3.1.2 Major Products Tested

?Short circuit making & breaking capacities -120 kA, 575V and & 50 kA, 525 V for Switchgear.

?Short time withstand current test - 120 kA for 1 s or 70 kA for 3 s at Savli and 50 kA for 1 s, at Makarpura

?Impulse Test - 1600kV, 80kJ and High Voltage one minute power frequency test - dry & wet - 700kV, 350kVA.

?20kA & 10kA stabilized High Current source for temperature rise test.

?Time current characteristics up to 40kA, 40V

?Mechanical endurance test set up for HT circuit breaker up to 145 kV.

?170 Channel computerized temperature scanner.

?Electrical endurance and Making & Breaking setup, 2.5kA at 415V, 2 kA at 690V, 1 kA at 415V, - 200A at 415V

?24kV, 1.2/50 µs Impulse generator

?Ring wave cum current surge generator. Current surge - 3000A,8/20 microsec, Ring wave - 250A, 0.5 microsec 100 kHz

?Computerized single phase & three Phase Relay testing kit.

?Feeder load unit - 4 Nos. (each of 8 ways outgoing feeder).

0?Environment (Humidity) chamber: - 40 C to +180 C, Size: 950 mm x 1000 mm x 950 mm.

0?Cold chamber : - 65 C, Size : 580mm x 550 x 1120 mm

?IP test ( Degree of Protection ): 40 Ton, Size: 6.8 Mtr x 5.8 Mtr. x 5.0 Mtr

?Time current characteristics

?Short-time withstand current

?Busducts

?HT Panels

?HT Circuit

?Breakers

?RMU

?Bushings

?Transformer Tap changer

0

1. Switchgear Testing

1.1 Introduction

ERDA's Switchgear test facilities are being utilized for certification of products to be exported to European and Middle East markets, under the ASTA mark. Intertek Testing and Certification, UK has accredited ERDA test facilities for testing of electrical products for issuing ASTA-BEAB certificates

Impulse Laboratory

State-of-Art Switchgear Laboratory at ERDA

120 kA Short Circuit Laboratory at Savli

3Electrical Research & Development Association

ERDA News

1.3.2.2 Major Products Tested Recently

?Development testing for Auto Transfer Switch (ATS) as per IEC and UL standard. This ATS was having rating of 400A, 480V and 600A, 525 V with a minimum change over time of 15 millisecond.

?Type tests on three phase, 2000A sandwich bus duct as per Japanese standard in the presence of Mr. Jun Harayama -Japan Electrical & Environment Tech. Lab, Japan and Mr. Kim-Ji Chang - Pacific MK, Malaysia

1.3.2 40kA, 1Ø Stabilized High Current Source

1.3.2.1 Major Tests

Switchgear section is having a customized high current source, which is used for verification of time current characteristics of ACB/MCCB, Fuse, etc.

The source has Continuous current rating:6 kA and Short time current rating: 40kA

?Temperature-rise test

?Time current characteristics

?Short-time withstand current

Testing of 20 kA Bushing

20 kA High Current Source

40 kA Time Current Characteristic Test Facility

400A Auto Transfer Switch Testing

2000A Sandwich Bus Duct Temperature Rise Test as Per Japanese Standard

Temperature Rise Test on Sandwich Bus Duct for Intertek Certification

4 Electrical Research & Development Association

ERDA News

?Recharging time of operating device

?Duration of opening & closing command impulse

?Bounce measurement

?Time-travel chart

All the above characteristics can be recorded at :

?Rated supply voltage & rated filling pressure for operation

?Maximum supply voltage & maximum filling pressure for operation

?Maximum supply voltage & minimum functional pressure for operation

?Minimum supply voltage & minimum functional pressure for operation

?Minimum supply voltage & maximum filling pressure for operation

1.3.3 Computerized Circuit Breaker Analyzer Kit & Mechanical Endurance Test Set up for HT Circuit Breaker upto 145kV

1.3.3.1 Major Tests Conducted

The facility has automated circuit breaker test system for monitoring & evaluating, characteristics of various circuit breakers as per IEC: 62271 -100 - 2008 & as per customer requirement. Four breakers can be tested in parallel for mechanical operation test.

?Operating characteristics

?Time-travel characteristics

Horizontal Load Test on Sandwich Bus Duct as per Japanese Standard

4000A Temperature Rise Test on Sandwich Bus Duct for Intertek Certification

5000A Temperature Rise Test on Sandwich Bus Duct for Intertek Certification

Mechanical Endurance Test Facility for HT Breaker

1.3.4 1Ø & 3Ø Power System Simulator Relay Test Setup for all Types of Relay

?ERDA - Switchgear Lab has expertise in testing for all kinds of static & numerical relays.

?Maximum source configurations are 6 - voltage & 6 - current sources or 12 - current sources.

?High range current sources with high power output

Ø1450VA, 3150VA & 6x75VA Constant power output.

Ø1675VA, 3225VA for 1.5 & 190A, 330A & 67.5A continuous in steps of 0.001A

(190A output is capable to do testing of 5A relays up to 10-15 times (Highset))

?All sources are independantly controlled with frequencies & phase angle.

?Frequency output:

Range : 0.1Hz - 2kHz & DC in steps of 0.001 Hz, DC - 3.1kHz Transient

?Phase angle output :

Range : 0 - 359.9 Degree(Lag/Lead insteps of 0.1 degree)

?6-voltage & 6 - current sources are capable to do testing of end - to - end scheme testing with backup protection using one PC.


ERDA News

1.3.5 40 Ton IP Test Facility - A Unique Test Facilities in Asia

Relay Testing Setup

Humidity Test Chamber (-40° C To 180°C)

Oven (Upto 180°C)

Computerised Setup for Characteristics (for MCP, RCCB, RCBO, MCCB, DOL Starter. etc.)

40 Ton IP Test Facility

ERDA has three IP test chambers as per following details (IP5X & IP6X):

?Chamber 1: 5.8m (l) x 6.8m (w) x 5 m (h) with 40 Ton payload

?Chamber 2: 2.5m (l) x 1.8m (w) x 2.5m (h) with 5 Ton payload

?Chamber 3: 2.5m(l) x 1.8m (w) x 2.5m (h) with 5 Ton payload

IPX1, IPX2, IPX7, IPX8 Facilities also available

?PLC based Electrical Endurance and Making & Breaking setup

?Relay, MCB, RCCB, RCBO, MCCB, ACB, SFU, SDF, SD, DOL Starter, Star Delta Starter, Air Break Contactors, Vacuum Contactor, Push Button Limit Switch, Rotary Switch, Selector Switch, Push Button, etc.

?Voltage & Current rating up to :

2.5kA at 415V, 2.0kA at 690V, 1.0kA at 415V, 200A at 415V

1.3.6 1kA, 2kA & 4kA PLC Based Electrical Endurance Test Setup

1.3.6.1 Major Products Tested:

1.3.6.2 Testing Specifications:


ERDA News

Co., Ltd., Malaysia.

?Mr. Darren Ng of Furutec Electricals SDN BHD, Malaysia.

?Mr. Maximo S. Espino of M/s. Industrial Electrical Project, Kuwait.

?Mr. Omar Salem of M/s. Arabian Gulf Industrial Co. Kuwait.

?Mr. Bui Hong Phuoc of M/s. HONG THINH Jont Stock Company, Vietnam.

?Mr. Khalid Hashem of M/s. ABB Arab, Egypt.

?Mr. Rajesh K Lakhwani of Al Rebou Elct. Switchgear, Abudhabi

?Mr. Thiagarajan Ponmani of M/s.Alfanar Electrical Systems, Riyadh, K.S.A

?Mr. P. K. Kashyap of Matrix Switchgear Industries L.L.C., Sharjah

?Mr. Prakash of M/s. Safety Electrical Trading Co. W.L.L., UAE

?Mr. K. Shrinivas of Powertech Switchgear Industries F.Z.E., UAE

?Mr. Adrian Sheridan of Powerbar Gulf LLC RAK Factory, UAE.

?Mr. P. K. Basu of Al Ishraf Electrical & Sanitary CONC. Co. L.L.C. UAE

?Mr. Sami Farraj, of M/s. Farraj Trading & Manufacturing Co., UAE.

?Mr. V. M. Kareem Gani of M/s. ETA-PCS SWITCHGEAR MANUFACTURING L.L.C., UAE.

The most reliable way to determine the corrosion and environmental behavior of a component is to expose it to the environment under service conditions and to assess the corrosion by means available in that particular case. In nearly every instance, this procedure is slow and costly. It is necessary to simulate and accelerate. The test can be accelerated in the hope that the results obtained in a few hours or a few days can predict a service life of years. Difficult to be sure, yet such considerations are the concerns of the environmental engineer. An accelerated salt spray corrosion test is one in which specimens are exposed either continuously or intermittently to a fine mist of salt- water solution.

1] Acceptance testing to assess the quality of a protective coating, metallic or non metallic. The salt spray test for galvanized steel (ASTM B 117) is the most commonly used method.

2. ERDA's Environmental Corrosion Facility: The Salt Spray Test

2.1 Introduction

2.2 Reasons for Laboratory Corrosion Testing

1.3.7 Capacitance Discharge Test

Switchgear Section has carried out Capacitance Discharge Test on High Burden Relays as per IEC Standards. This relay was tested with a capacitor of 0.5 µF.

4kA PLC Based Electrical Endurance Test Setup with 8 Channel Digitizer & Amplifier Measuring System

Test set up for Capacitance Discharge Test

1.4 Recent International Visitors / Customers to Switchgear Laboratory

?Mr. Sung Puay Kiang of M/s. Sunlight Electrical Pvt. Ltd., Singapore.

?Mr. Kullakavandar of M/s. Pacific MK Corporation, Malaysia.

?Mr. Nguyen Thanh Dien of M/s. DUY HAO Engineering


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?Zinc and Zinc-alloy plating

?Electroplated Chromium, Nickel, Copper, Tin

?Coatings not applied electrolytically, such as Zinc Flake Coatings according to ISO 10683

?Organic coatings

2] Testing to predict service life a test to determine how long a material will survive in specified environment.

3] Testing to determine suitability of component / material for a specified environment.

4] Test to determine the best material / component for an environment.

5] Testing to determine corrosion resistance of a new material / component.

Overall View of Salt Spray Chamber

Salt Spray Chamber with Lid Open Showing Salt Mist Fog Inside Chamber

Close Up of Control Panel of Salt Spray Chamber

2.3 Typical Uses

?Phosphated surfaces (with subsequent paint / primer / lacquer / rust preventive)

Bracket Before and After Salt Spray Test

Hot-dip galvanized surfaces are not generally tested in a salt spray test (see ISO 1461 or ISO 10684). Hot-dip galvanizing produces Zinc Carbonates when exposed to a natural environment, thus protecting the coating metal and reducing the corrosion rate. The Zinc Carbonates are not produced when a hot-dip galvanized specimen is exposed to a salt spray fog, therefore this testing method does not give an accurate measurement of corrosion protection. ISO 9223 gives the guidelines for proper measurement of corrosion resistance for hot-dip galvanized specimens.

Painted surfaces with an underlying hot-dip galvanized coating can be tested according to this method.

Testing periods range from a few hours (e.g. 8 or 24 hours of phosphated Steel) to more than a month (e.g. 720 hours of Zinc-Nickel coatings, 1000 hours of certain Zinc flake coatings).


ERDA News

(b) Participated / Represented in: District / State / National / International level competitions with or without securing any position

2. Education Scholarship for Children of ERDA Employees has been started to inculcate learning as a passion among children of ERDA employees and to promote education in science and engineering among young students. A regular student who has scored distinction in SSC or HSC examination in first attempt under the state or central educational boards and who is pursuing further education is eligible for the scholarship. In addition to the scholarship, the beneficiary students will be given special exposure to R&D activities being carried out in ERDA though workshops, lectures, educational tours of various ERDA test facilities etc. These ch i ldren wi l l a l so be e l ig ib le for Project/Training/Internship at ERDA, if required (as part of their academic curriculum) during their graduation and post-graduation programs in science and technology.

3. Emergency Medical Assistance Scheme has been created to assist ERDA employees in providing financial assistance in medical emergencies and accidental emergencies after exhausting the Personal Accident Scheme / Mediclaim Scheme entitlements as per ERDA rules and his/her own personal Mediclaim policy if any.

All confirmed ERDA employees who are diagnosed with diseases/disorders or accidents which involves high medical expenditure for treatment, such as cancer, heart and circulatory system disorders, liver & blood disorders, renal disorders, nervous system disorders, child birth & related complications (other than covered under Maternity Benefit Act) are covered under this scheme.

ERDA believes in developing a fully competent workforce which is capable of supporting the company to meet its goals effectively and efficiently. This is done through various functional, technical and behavioral training programmes conducted throughout the year. The employees are nominated for both in house and external training programmes.

The "customer is always right" is a famous business slogan. The underlying truth behind this statement is recognizing that customers are the life blood for any business. Understanding the importance of good customer service is essential for a healthy business in creating new customers, keeping loyal customers, and developing referrals for future customers.

4. Customer Service Orientation Training

2.4 Technical Specifications of the ERDA Test Chamber

1. Chamber useful volume: 1000 Liters

2. Chamber dimensions: 129 cm (l) x 106 cm (d) x 78 cm (h)

3. Accuracy of temperature control in chamber: ±1 °C

ERDA cares about its employees and is committed to their welfare. The basic purpose of employee welfare is to enrich the life of its employees and to keep them happy and motivated. ERDA believes in investing for the well-being of employees through employee friendly schemes and policies. The following polices have been formulated for the benefit of employees:-

1. Sports Scholarship Policy has been initiated to encourage budding sports talent among the children of ERDA employees by giving them financial assistance in form of sports scholarship for their playing kits, sports equipment, training etc. A child is eligible for the scholarship if he has:

(a) Participated/Represented and secured: 1st, 2nd or 3rd position in inter school or inter university tournament

3. Employee Welfare Activities

M.S Bolt Before and After Salt Spray Test


ERDA News

To improve the customer service orientation (CSO) of employees, a workshop for CSO was initiated for 'Management level' employees. The workshop consisted of combination of presentations, case studies and management games aimed at making the employees aware of the importance of "Outstanding Customer Service". The employees actively participated in the training session. Due to the overwhelming response received from the employees, the training will also be extended to all 'Engineers/Scientist level' employees.

Glimpses of Customer Service Orientation Training Programme

5. Important Visitors

1. Mr. Leopoldo Vazquez ABI Representative in Mexico and Mr. Acuna Hernandez Hector Quality and Testing Manager CFE/LAPEM, Mexico visited ERDA on 14th October 2013.

2. Dr. S Gomathinayagam, Executive Director and Mr. Rajesh Katyal of C-WET, Chennai (A Govt. of India Laboratory of MNRE) visited ERDA on 9th October 2013 to explore possibilities of Collaboration in Wind Turbine Testing and Wind Hydrogen R&D projects.

3. Electrical Engineering Students from various Engineering Colleges visited our Laboratories to see our facilities as part of curriculum requirements.

Visitors from Mexico in Discussion with Acting Director, ERDA and Other Executives

Dr. S Gomathinayagam, Executive Director and Mr. Rajesh Katyal of C-WET, Chennai with Acting Director and Other Senior Staff Members of ERDA

Undergraduate Electrical Engineering Students at Chemburkar Learning Centre in an Orientation Lecture

9


ERDA News

6. Seminar on Total Power Quality Management

ERDA Partnered with FICCI & ICPCI for organizing a Seminar on "Total Power Quality Management" on 25th October 2013 in Chemburkar Learning Centre. A total of 60-65 participants from ERDA, Industries and Power Utilities took part in the program.

Inaugural Session and a View of Participants

7. Training Courses Conducted

During the year the following regular training courses were conducted as per schedule and all programmes were well attended:

Sr. No. Title Dates

1 Evaluation of Cables & Accessories 27-28 June 2013

2 Condition Monitoring and Health Assessment of Power Transformers 30-31 July 2013

3 Design Aspects & Performance Evaluation of Motors & Pumps 17-18 October 2013

4 EMI/EMC Testing of Naval Equipment 17-18 December 2013

5 Quality Assurance of Wiring Accessories-Switches, Plugs & Sockets 19-20 December2013

A view of Participants and Group Photo with our Senior Staff Members

Coating, Holography, Hydrogen Fuelled Electrical

Generator, LED - based Lamp and Electroless Coating

were arranged on that day. The students were shown

around the laboratories. In all, 450 students from

various educational institutions participated in this

programme. Students and teachers showed keen

interest in the demonstrations.

8. Open House 2013

ERDA organized the 'Open House - 2013' programme

on 26th November 2013 for the benefit of students of

Higher Secondary (Science Stream) schools. Industrial

Training Institutes and Polytechnics. Demonstrations of

Electromagnetic propulsion, GIS Mapping, RTV Silicone

Electrical Research & Development Association 11

ERDA News

10. Diwali Celebrations

ERDA celebrated Diwali festival on 1st November 2013 with a glittering function organized by ERDA Welfare Committee.

9. Customer Feedback: Extracts from Apprecation Letter

A letter of appreciation from a customer has lauded ERDA staff for excellent service provided to them. The customer has stated"…Excellent Team of Officers having though knowledge of testing provided us required information right from the day we submitted samples and till the time reports were received by us. Undoubtedly ERDA is best testing laboratory in India, please keep it up…"

Students at Lamp Testing Section

Students in Technology Centre

Dr. M.K. Shah, Acting Director ERDA Inaugurating the Diwali Festival Celebrations by Lighting the Lamp

Students at Transformer Testing Laboratory

A View of ERDA Audience During the Diwali Festivities

11. Technical Article

Environmentally Friendly WO Doped Ag-SnO 2 2

Contacts Prepared by Powders Processed through Electro-chemical Route

During last few years a sizable number of investigations has been carried out with the aim to find a substitute for Silver - Cadmium oxide (Ag/CdO), which is the standard contact material for contactors for more than three decades now. The use of Cadmium and Cadmium-oxide is now being discouraged due to its toxicity, as Cadmium is poisonous and can cause serious health problems if ingested & inhaled. Cadmium compounds are considered to be carcinogenic. Acute exposure to Cadmium fumes damage the lungs as well as the kidneys. Therefore, it is now banned in countries such as Sweden, Japan and USA. Owing to the toxic

1.0 Introduction:


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optimal parameters for pressing, sintering were decided after carrying out various experiments. The physical properties like density, microstructure, conductivity & micro - hardness were studied for each composition of dopant. Then these contact tips were brazed on contact lugs of a commercially available contactor & electrically evaluated (endurance study, make, make-break study, & temperature rise study) for AC-3 rating for 32 A as per IS: 13947 (Pt. IV) Section I - 1993 and IEC 947-4-1(1990) (specification for low voltage switchgear & control gear) and an optimal composition has been identified. The optimal composition was subjected to AC-4 rating testing and it has passed this rating class test also.

Contact materials were characterized/evaluated using the following techniques:

1. Physical & Microstructural Characterization.

2. Electrical Performance Evaluation.

For purpose of this study, Ag-SnO contact material 2

containing 8.7 wt% of SnO and with various 2

concentrations of dopant were selected. The density obtained is about 98.61% of the theoretical density for Silver, (see Table 1).

For contact material with Tin oxide content of 8.7 wt% along with 0.3 wt % of ternary oxide (dopant), the density obtained is 98.41% of the theoretical density. This indicates good compacting properties. In-case of Tin oxide of 8.7 wt% with 0.5 wt% ternary oxide (dopant), the density obtained is 98.31% of the theoretical density, which is relatively less than the density obtained for contact containing 0.3 wt% ternary oxide. In-case of Tin oxide content of 8.7 wt% with 0.7 wt % ternary oxide (dopant), the density obtained is 97.50% of the theoretical density, which is relatively less than that obtained for contacts containing 0.3wt% & 0.5wt% ternary oxides.

Table 1: Physical Properties of Contacts with Various Concentrations of Dopant

3.0 Results & Discussion:

3.1 Physical & Microstructural Characterization

i) Density:

properties of Cadmium, many laboratories all over the world are engaged in the development of substitute material for Silver - Cadmium oxide.

From available literature, it may be concluded that, Silver-Tin oxide based contact materials are the most likely candidates for replacing Silver-Cadmium oxide contacts. However, it is also observed that Silver Tin Oxide contacts show more temperature rise when compared to Cadmium Oxide contacts. This is due to the higher thermal stability of Tin oxide. This problem is usually tackled by adding ternary oxides (dopant) such as Tungsten oxide, Indium oxide, Bismuth oxide, etc.

Silver-Tin oxides are commonly manufactured by Internal Oxidation (German) and Powder Metallurgy (Japan) routes. These require Silver powder of high purity, fineness and spherical morphology. This increases the cost of Silver-based contacts. In addition to this, these methods have limitations such as internal oxidation, inability to incorporate greater than 10% Tin oxide material, as well as long process time. Further, in the powder metallurgy process, needle like structures are observed to form which lead to embrittlement of the material.

In the present work, a new electro-chemical method for preparing AgSnO contact tips is proposed. The process 2

described here can be applied to many Silver - metal oxide systems, and is not limited in terms of composition by solid solubility considerations and produces fine homogeneous microstructures, which, as in many other metallurgical applications, are now recognized as being of paramount importance in obtaining optimum performance.

Powders of Silver tin oxide with dopant were prepared using the electro-chemical route. In this process, through a chemical reaction, Silver salt dissociates to give free Silver which gets deposited on Tin oxide particles. The ternary metal oxide is also added during the process. The presence of Silver & dopant was confirmed using EDS. The powders were prepared with different concentrations of dopants varying as 0.3 wt%, 0.5 wt% & 0.7 wt%. The contact tips were prepared using the powder metallurgy (pressing, sintering & secondary operations like hot pressing) route. The

2.0 Experimental Work:

Sr. No.

Contact Composition TheoreticalDensity

Micro-Hardnessat 40 g, VPN

Conductivity, % IACS

1 Without dopant 98.61 86 84

2 0.3 wt % dopant 98.41 87 78

3 0.5 wt % dopant 98.31 87 77

4 0.7 wt % dopant 97.70 87 76


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3.2 Electrical Performance:

3.2.1 Make-Break Study:

In order to study the electrical performance of the contacts, the commercially available 32 A contactor was used. The contact tips of required sizes and shape used in this commercial contactor (Fig. 2) were prepared and brazed onto the lugs & then they were subjected to the AC-3 & AC4 rating study as per IS 13947 - Section 4 part 11993 and IEC 947-4-1(1990) (specification for low voltage switchgear & control gear). Details of the make-break & performance (endurance) testing are presented below.

For carrying out make break test, parameters used for testing were as per clause No. 8.3.3.5. of IS: 13947 (Pt. IV) Section I - 1993 and IEC 947-4-1(1990) (specification for low voltage switchgear & control gear).

For evaluation of the contact tips, loss of material in terms of wt% after testing was computed.

It is observed that 0.3 wt% ternary oxide (Tungsten oxide) containing contacts showed minimum wear among other compositions tested i.e. without ternary oxide, 0.5 wt% ternary oxide (Tungsten oxide) and 0.7 wt % ternary oxide (Tungsten oxide) containing contacts. It is also observed that contact material with 0.7 wt% ternary oxide showed maximum wear, see Table 2 and Fig. 3. Thus, there appears to be an optimal level of Tungsten oxide incorporation beyond which the wear properties markedly degrade.

Utilization Category : AC3

Rated operational Voltage (Ue) : 415 V

Rated Operational current (Ie) : 32 A

Total No. of operations : 50

Off time : 10 sec

Test current : 10 times rated current

Power factor : 0.45

Total No. of Operations : 50

On Time : 45.3 sec

Off Time : 30 sec

Applied voltage : 436.5 V

Test current : 8 times rated current

Power Factor : 0.45

Conditions for Testing:

Make Only:

Making & Breaking Capacity:

These observations show that as the ternary oxide content increases, the density of the contact material decreases. This may be due to poor ductility of Tungsten oxide, which prevents attainment of adequate compaction during the die-pressing operation.

Hardness of the Silver Tin oxide composite is affected by the microstructure, wt% of Tin oxide and particle size. Further, secondary working also changes the porosity level and grain size of the compact.

In the present work, Tin oxide particles used are fine and uniformly distributed and hence the hardness is uniform and high. The hardness obtained without ternary oxide (0 wt%), 0.3wt%, 0.5wt% & 0.7wt% ternary oxide levels is in the range of 86-87 VPN. This indicates that the presence of ternary oxide does not affect hardness to any significant extent (See Table. 1).

Microstructure (see Fig. 1) shows uniform dispersion of Tin oxide particles in Silver matrix. In general, results indicate that electro-less deposition techniques allows uniform distribution of Tin Oxide particles in the matrix of Silver and also controls degree of agglomeration of the particulates. In addition to this, volume loading of Tin oxide can be controlled. The well dispersed Tin oxide particles serve to increase the arc welding resistance at the contact points in switches and circuit breakers. Further such particulates are not expected to grow into needle like crystals on thermal aging as they are well separated from each other. The uniform dispersion of Tin oxide particulates in Ag matrix is expected to give uniform erosion resistance and hence longer useful life of the contact. It was also noted that the incorporation of ternary dopants did not have any significance impact on the basic Ag-SnO2 composite. This is expected as the content of the ternary dopants is extremely low. As far as the inter-particle spacing of the Tungsten oxide dopants is concerned, it is found to be random and varies from location to location in the sample (Fig. 1).

Electrical conductivity measurements indicate that Silver Tin oxide contacts prepared by the electro-less technique have conductivity comparable to Ag-CdO contacts. For Ag-SnO contact without incorporation of 2

ternary oxide (dopants), the conductivity was 84% ICAS. After incorporation of 0.3 wt%, 0.5 t% and 0.7 wt% dopants, the conductivity values are in the range 78% to 76%. The trend of decreasing conductivity with increasing dopant content is expected.

ii) Hardness:

iii) Microstructure:

iv) Conductivity:


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Thus AC3 electrical performance studies show that contact with dopant level of 0.3 % is the most promising material. Subsequent to this finding, new contact tips were prepared & contactor was subjected to AC4 testing. The contact tips successfully passed in this rating also.

o It is possible to obtain dense and uniform deposition of Silver (Ag) on a colloidal solution of Tin oxide (SnO ) particulates using the electro-less deposition 2

technique.

o It is also possible to have concurrent deposition of Silver and ternary dopants in an efficient manner using the electro-less technique.

o AC3 make-break and endurance testing on the Silver - Tin oxide - Tungsten oxide (Ag-SnO -WO ) 2 3

system indicate that the most optimal degradation & wear resistant properties are obtained with incorporation of about 0.3 wt% dopant in the Ag-SnO system. 2

o The optimized ternary composition has also withstood AC4 rating.

o The process developed is suitable for other metal oxide dopants also.

4.0 Conclusions:

Table -2: Total Wt % Loss of Material after Make, Make - Break Testing

Sr. No.

Contact Composition Total Wt% loss of Material

1 Without Dopant 5.2

2 0.3 wt % Dopant 2.5

3 0.5 wt % Dopant 2.7

4 0.7 wt % Dopant 5.3

3.2.2. Performance (Endurance) Test:

Conditions for Testing:

For carrying out performance (endurance) testing, the test parameters used were as per clause No. 8.3.3.6 of IS: 13947 (Pt. IV) Section I-1993 and IEC 947-4-1(1990) (specification for low voltage switchgear &control gear).

The wear behavior of the contact tips was evaluated using mass loss measurements. It was observed that 0.3 wt% ternary oxide (Tungsten oxide) containing contacts showed the highest wear resistance among other compositions i.e. without ternary oxide, 0.5 wt% ternary oxide, tungsten oxide, and 0.7 wt % tungsten oxide containing Ag-SnO . 2

The results obtained for endurance testing indicate that the wear loss is the highest for 0.7 wt% Tungsten oxide containing Ag-SnO contacts. The wear loss data for 2

endurance testing has been systematically compiled in Table 3 and shown in Fig. 4.

Utilization Category : AC3

Rated operational Voltage (Ue) : 415 V

Rated Operational current (Ie) : 32 A

Calculated Parameters Measured Parameters(Average)

Applied voltage(V) : 415x1.05= 436 447V

Test current (I) Double the rated current : 64 A 64.4A

Power Factor (cosf) : 0.45 0.448

Total No. of operations: 6000

On time : 50 millisecond

Off time : 10 sec

Table 3: Total Wt % Loss in Material in Endurance Tests

Sr. No.

Contact Composition Total Wt% loss of Material

1 Without Dopant 4.6

2 0.3 wt % Dopant 1.6

3 0.5 wt % Dopant 4.1

4 0.7 wt % Dopant 15.5

Fig. 1: Optimized Ternary Silver – Tin Oxide Composition with 0.3 wt% Dopant

Fig. 2: Brazed Contact Tip Configuration for Electrical Tests


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a 3-year-old from being run over by an errant train, the

child's grateful father rewarded him by teaching him to

operate a telegraph. By age 15, he had learned enough to

be employed as a telegraph operator. For the next five

years, Edison traveled throughout the Midwest as an

itinerant telegrapher, subbing for those who had gone to

the Civil War. In his spare time, he read widely, studied

and experimented with telegraph technology, and

became familiar with electrical science.

In 1869, Edison moved to New York City and developed

his first invention, an improved stock ticker, the

Universal Stock Printer, which synchronized several

stock tickers' transactions. The Gold and Stock

Telegraph Company was so impressed, they paid him

$40,000 for the rights. Edison was only 22 years old.

With this success, he quit his work as a telegrapher to

devote himself full-time to inventing.

In 1870, Thomas Edison set up his first small laboratory

and manufacturing facility in Newark, New Jersey, and

employed several machinists. As an independent

entrepreneur, Edison formed numerous partnerships

and developed his products for the highest bidder.

Often that was Western Union Telegraph Company, the

industry leader, but just as often, it was one of Western

Union's rivals. In one such instance, Edison devised for

Western Union the quadruplex telegraph, capable of

transmitting two signals in two different directions on

the same wire, but railroad tycoon Jay Gould snatched

the invention from Western Union, paying Edison more

than $100,000 in cash, bonds and stock, and generating

years of litigation.

Becoming an Inventor

12. Thomas Alva Edison

Inventor Thomas Alva Edison was born on February 11,

1847, in Milan, Ohio. He was the last of the seven

children of Samuel and Nancy Edison. Thomas's father

was an exiled political activist from Canada. His mother,

an accomplished school teacher, was a major influence

in Thomas' early life. An early bout with scarlet fever left

him with hearing difficulties in both ears, a malady that

would eventually leave him nearly deaf as an adult.

At age 12, Thomas convinced his parents to let him sell

newspapers to passengers along the Grand Trunk

Railroad line. Exploiting his access to the news bulletins

teletyped to the station office each day, Thomas began

publishing his own small newspaper, called the Grand

Trunk Herald. The up-to-date articles were a hit with

passengers. This was the first of what would become a

long string of entrepreneurial ventures where he saw a

need and capitalized on opportunity.

While he worked for the railroad, a near-tragic event

turned fortuitous for the young man. After Edison saved

Younger Years

Early Career

Fig. 3: Graph Showing Wt % Loss in Different Contact

Compositions after Make Break Testing

Fig. 4: Graph Showing Weight % Loss of Material in Different

Compositions of Contact- Material after Performance Test


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business manager. The laboratory in West Orange was

too large and complex for any one man to completely

manage, and Edison found he was not as successful in his

new role as he was in his former one. Edison also found

that much of the future development and perfection of

his inventions was being conducted by university-

trained mathematicians and scientists. He worked best

in intimate, unstructured environments with a handful

of assistants and was outspoken about his disdain for

academia and corporate operations.

On a couple of occasions, Edison was able to turn failure

into success. During the 1890s, he built a magnetic iron-

ore processing plant in northern New Jersey that

proved to be a commercial failure. Later, he was able to

salvage the process into a better method for producing

cement. On April 23, 1896, Edison became the first

person to project a motion picture, holding the world's

first motion picture screening at Koster & Bial's Music

Hall in New York City.

Thomas Edison died of complications of diabetes on

October 18, 1931, in his home, "Glenmont," in West

Orange, New Jersey.

The article is reproduced with minor editing from

Wikipedia.

Reference:

Edison Illuminating Company

Industrialist and Business Manager

The 1880s were a busy time for Thomas Edison. After

being granted a patent for the light bulb in January 1880,

Edison set out to develop a company that would deliver

the electricity to power and light the cities of the world.

That same year, Edison founded the Edison Illuminating

Company-the first investor-owned electric utility-

which later became the General Electric Corporation.

In 1881, he left Menlo Park to establish facilities in

several cities where electrical systems were being

installed.

In 1882, the Pearl Street generating station provided

110 Volts of electrical power to 59 customers in lower

Manhattan. In 1884 Edison's wife, Mary, died, and in 1886,

he married Mina Miller, 19 years his junior. In 1887,

Edison built an industrial research laboratory in West

Orange, New Jersey, which served as the primary

research laboratory for the Edison lighting companies.

He spent most of his time there, supervising the

development of lighting technology and power systems.

He also perfected the phonograph, and developed the

motion picture camera and the alkaline storage battery.

Over the next few decades, Edison found his role as

inventor transitioning to one as industrialist and

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