Slides from our Understanding DGA Techniques and Interpretations Webinar. This technical webinar discussed the various gases found in transformer insulating oil, their relationship to various faults found in transformers, and tools to detect these faults.
Watch the webinar here - http://bit.ly/2Ea2DZE
Dissolve gas anylysis measurement and interpretation techniqueArun Ramaiah
DGA measurement & interpretation technique: it is a testing of insulating oil of transformer, which give the data about the internal damage, gases produce in the oil occurs due to overheating, acring etc. interpretation technique- gives the idea about he fault that causes by gases.
Dissolved Gas Analysis of conventional diagnosis techniques for transformer Hardikarathod
This presentation based on conventional transformer diagnosis techniques which is dissolved gas analysis. In the technique included topics such as Key Gas Method, Gas Ratio Methods, Duval's Triangle, Effect of Stray Gassing in DGA, Partial Discharge Identification using DGA.
Slides from our Understanding DGA Techniques and Interpretations Webinar. This technical webinar discussed the various gases found in transformer insulating oil, their relationship to various faults found in transformers, and tools to detect these faults.
Watch the webinar here - http://bit.ly/2Ea2DZE
Dissolve gas anylysis measurement and interpretation techniqueArun Ramaiah
DGA measurement & interpretation technique: it is a testing of insulating oil of transformer, which give the data about the internal damage, gases produce in the oil occurs due to overheating, acring etc. interpretation technique- gives the idea about he fault that causes by gases.
Dissolved Gas Analysis of conventional diagnosis techniques for transformer Hardikarathod
This presentation based on conventional transformer diagnosis techniques which is dissolved gas analysis. In the technique included topics such as Key Gas Method, Gas Ratio Methods, Duval's Triangle, Effect of Stray Gassing in DGA, Partial Discharge Identification using DGA.
Boiler purge is the basic process of resetting boiler before lightup. This presentation explains the logic, schematics & working of purge procedure. For enhanced knowledge of this topic, I can be reached at tahoorkhn03@gmail.com.
Load sound power levels for specification purposes of three-phase 50 Hz and 6...Power System Operation
Load sound power levels for specification purposes of three-phase 50 Hz and 60 Hz liquid-filled power transformers.
In the industry there is an increasing awareness observed that load sound, depending on transformer parameters and loading, contributes to, and may even dominate the total sound level of a transformer in service. This results in a growing tendency to specify the permissible sound level not only for no-load operation, but also for the loaded transformer when purchasing new transformers.
Specifying a realistic load sound level for power transformers is often challenging due to limited availability of reliable and validated information. This easily leads to physically unrealistic load sound level specifications, either unnecessary high, e.g. NEMA TR 1 standard [1], or, as has been a trend in recent years, unachievable low without using external sound mitigation measures.
The book describes the basics of heat rate, how it is to be calculated, the mass balance of the Thermal power station and the requisite data to be collected, the boiler efficiency, turbine efficiency and everything related to the heat rate of the Power Plant.
BOILER PRESERVATION.BOILER START UP IN COLD,WARM AND HOT AND EXTREMELY HOT CONDITION.BOILER INTERLOCKS AND PROTECTION.BOILER SAFETY.BOILER CHEMICAL DOSING
Heat/light/electrical energy is out today’s necessity and has scarcity also. Energy conservation is key requirement of any industry at all times.
In general, industries use heat energy for conservation of raw material to finished product. The source of heat energy is generally saturated or super heated steam. The steam generation is common use one boiler with carity of fuels. Whatever may be the fuel the generation should be as economy as possible which adds to the product cost. Further the usage of steam and recycling steam condensate back to boiler is an art depending on plant layouts.
In this project the steam generator is water tube boiler fired with rice husk. The steam is transferred to the tyre/tube moulds where tyres/tubes are cured while the heat is rejected to the tyres the condensate forms and this condensate is put back to the boiler. While doing so the steam is also stopped back to boiler without rejecting complete heat to the product. This gets flashed into atmosphere at feed water tank. The science of separation of condensate from steam saves energy. Better the separation more the fuel conservation.
In the steam generator the fuel is burnt to heat the water and form steam. This fuel burnt flue gas carries lot of energy, out through chimney. Prior to exhausting through the heat left in flue need to be recovered, through heat recovery mechanisms’. In this project an air-preheater condensate heat recovery unit is the major energy consuming station.
This is great Presentation with 3D effects which is all about production of ammonia from natural gas.
I am damn sure you will be getting everything here searching for.
its better to download it and then run in powerpoint 2013.
Boiler purge is the basic process of resetting boiler before lightup. This presentation explains the logic, schematics & working of purge procedure. For enhanced knowledge of this topic, I can be reached at tahoorkhn03@gmail.com.
Load sound power levels for specification purposes of three-phase 50 Hz and 6...Power System Operation
Load sound power levels for specification purposes of three-phase 50 Hz and 60 Hz liquid-filled power transformers.
In the industry there is an increasing awareness observed that load sound, depending on transformer parameters and loading, contributes to, and may even dominate the total sound level of a transformer in service. This results in a growing tendency to specify the permissible sound level not only for no-load operation, but also for the loaded transformer when purchasing new transformers.
Specifying a realistic load sound level for power transformers is often challenging due to limited availability of reliable and validated information. This easily leads to physically unrealistic load sound level specifications, either unnecessary high, e.g. NEMA TR 1 standard [1], or, as has been a trend in recent years, unachievable low without using external sound mitigation measures.
The book describes the basics of heat rate, how it is to be calculated, the mass balance of the Thermal power station and the requisite data to be collected, the boiler efficiency, turbine efficiency and everything related to the heat rate of the Power Plant.
BOILER PRESERVATION.BOILER START UP IN COLD,WARM AND HOT AND EXTREMELY HOT CONDITION.BOILER INTERLOCKS AND PROTECTION.BOILER SAFETY.BOILER CHEMICAL DOSING
Heat/light/electrical energy is out today’s necessity and has scarcity also. Energy conservation is key requirement of any industry at all times.
In general, industries use heat energy for conservation of raw material to finished product. The source of heat energy is generally saturated or super heated steam. The steam generation is common use one boiler with carity of fuels. Whatever may be the fuel the generation should be as economy as possible which adds to the product cost. Further the usage of steam and recycling steam condensate back to boiler is an art depending on plant layouts.
In this project the steam generator is water tube boiler fired with rice husk. The steam is transferred to the tyre/tube moulds where tyres/tubes are cured while the heat is rejected to the tyres the condensate forms and this condensate is put back to the boiler. While doing so the steam is also stopped back to boiler without rejecting complete heat to the product. This gets flashed into atmosphere at feed water tank. The science of separation of condensate from steam saves energy. Better the separation more the fuel conservation.
In the steam generator the fuel is burnt to heat the water and form steam. This fuel burnt flue gas carries lot of energy, out through chimney. Prior to exhausting through the heat left in flue need to be recovered, through heat recovery mechanisms’. In this project an air-preheater condensate heat recovery unit is the major energy consuming station.
This is great Presentation with 3D effects which is all about production of ammonia from natural gas.
I am damn sure you will be getting everything here searching for.
its better to download it and then run in powerpoint 2013.
Three basic methods used to control engine emissions:
1)Engineering of combustion process -advances in fuel injectors, oxygen sensors, and on-board computers.
2) Optimizing the choice of operating parameters -two Nox control measures that have been used in automobile engines are spark retard and EGR.
3) After treatment devices in the exhaust system -catalytic converter.
Biomass gasification is a chemical process that convert
biomass into useful convenient gaseous fuel. It has emerged as a promising technology to fulfill the increasing energy demands of the world as well as to reduce significantly the volume of Biomass waste generated in developing societies.
Gasification produce gases like CO,CO2, H2 and CH4; these gas released are called Syngas.
Gasification technology can be used for:
Household Fuel
Electricity and Steam Generation
In internal combustion engines as a fuel
In a gasifier, the biomass undergoes several different processes like drying, pyrolysis, combustion and gasification process
Prediction of Fault in Distribution Transformer using Adaptive Neural-Fuzzy I...ijsrd.com
In this paper, we present a new method for simultaneous diagnosis of fault in distribution transformer. It uses an adaptive neuro-fuzzy inference system (ANFIS), based on Dissolved Gas Analysis (DGA). The ANFIS is first “trained†in accordance with IEC 599, so that it acquires some fault determination ability. The CO2/CO ratios are then considered additional input data, enabling simultaneous diagnosis of the type and location of the fault. Diagnosis techniques based on the Dissolved Gas Analysis (DGA) have been developed to detect incipient faults in distribution transformers. The quantity of the dissolved gas depends fundamentally on the types of faults occurring within distribution transformers. By considering these characteristics, Dissolved Gas Analysis (DGA) methods make it possible to detect the abnormality of the transformers. This can be done by comparing the Dissolved Gas Analysis (DGA) of the transformer under surveillance with the standard one. This idea provides the use of adaptive neural fuzzy technique in order to better predict oil conditions of a transformer. The proposed method can forecast the possible faults which can be occurred in the transformer. This idea can be used for maintenance purpose in the technology where distributed transformer plays a significant role such as when the energy is to be distributed in a large region.
Pollutant,their formation and control in Internal Combustion EnginesHassan Raza
This presentation was prepared by Mechanical Engineering students during their Internal Combustion Course. Students belong to a very prestigious Engineering institute of Pakistan "University of Engineering and Technology Lahore"
Condition monitoring of rotating electrical machinesAnkit Basera
Condition monitoring of rotating electrical machines, Construction, Operation, Types, Specification Of Electrical Machines, Different Failure Modes Of Electrical Machines, Failure Modes And Root Causes In Rotating Electrical Machines
Stepper Motor Basics and Types with different modes of operation
1. Basics of stepper motor
2. step angle
3. types
4. Variable reluctance stepper motor
5. 1-phase-on mode
6. 2-phase-on mode
7. half step mode
8. PM stepper motor
9. Hybrid Stepper Motor
10. Application
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
3. • Internal faults in oil produce gaseous by products, including hydrogen (H2),
methane (CH4), acetylene (C2H2), ethylene (C2H4) and ethane (C2H6).
• The total of all combustible gases (TCG) with increases of gas generating rates
may indicate the existence of any one or a combination of thermal, electrical
or corona faults.
3
4. • Evaluation procedures
for DGA have been
implemented widely
based upon the
guidelines
recommended by IEC,
IEEE and CIGRE.
Hydrocarbon Gas Evolution In Transformer Oil Against Temperature
4
5. • The areas include normal operating temperatures go up to about 140 C, hot spots extend
to around 250 C and high temperature thermal faults to about 1000 C.
5
7. Key Gas Method
• The key gas method relates key gases to fault types and attempts to detect four fault types based
on key gas concentrations (C2H4, CO, H2, C2H2) expressed in ppm (part per million).
1) Overheating of oil: Decomposition products include C2H4 and CH4, together with small quantities
of H2 and C2H6. Traces of C2H2 may be formed if a fault is severe or involves electrical contacts.
The principal gas is C2H4.
2) Overheating of cellulose: Large quantities of CO2 and CO are evolved from overheated cellulose.
Hydrocarbon gases, such as CH4 and C2H4, are formed if a fault involves an oil-immersed
structure. The principal gas is CO.
3) Corona: Low-energy electrical discharges produce H2 and CH4, with small quantities of C2H6 and
C2H4. Comparable amounts of CO and CO2 may result from discharges in cellulose. The principal
gas is H2.
4) Arcing: Large amounts of H2 and C2H2 are produced, with minor quantities of CH4 and C2H4. CO2
and CO may also be formed if a fault involves cellulose. The insulation oil may be carbonised. The
principal gas is C2H2.
7
8. Sr No. Gas Fault Type
1 O2 and N2 non-faults
2 H2 corona
3 CO and CO2 overheating of cellulose insulation
4 CH4 and C2H6 low temperature overheating of oil
5 C2H4 high temperature overheating of oil
6 C2H2 arcing
Since the key gas method does not give numerical correlations between fault types and gas types directly,
the diagnosis depends greatly on experience.
8
9. Combustible Gassing Rate
• Once a suspicious gas presence is detected, it is important to sample again
and calculate the gassing rate of a gas, which can indicate whether the fault
that generated the gas is active or not.
𝑅𝑖 =
𝐶𝑖2 − 𝐶𝑖1
𝛥𝑡
𝐺
𝜌
gassing rate (ml/h or day) second sample concentration (ppm)
first sample concentration (ppm)
total oil weight (ton)
Density of oil (ton/m3)
actual operating time of a sampling interval (hour or day)
9
10. Gas Ratio Methods
• The gas ratio methods are coding schemes that assign certain combinations
of codes to specific fault types.
• The most commonly used gas ratio method is the Rogers Ratio Method
Ratios of gases
Code of range of ratios
C2H2/C2H4 CH4/H2 C2H4/C2H6
<0.1 0 1 0
0.1/1 1 0 0
1-3 1 2 1
>3 2 2 2
10
11. Rogers Ratio Method
Cases Fault Characteristic
Code of Range of Ratios
Example
C2H2/C2H4 CH4/H2 C2H4/C2H6
0 No fault 0 0 0 Normal aging
1 Partial discharges of low energy density 0 1 0 Discharges in gas-filled cavities
2
Partial discharges of high energy
density
1 1 0
As above, but leading to tracking or
perforation of solid insulation
3 Discharge of low energy 1 0 1 Continuous sparking in oil
4 Discharge of high energy 1 0 2
Arcing - breakdown of oil between
windings or coils
5
Thermal fault of low Temperature
< 150 C
0 0 1
General insulated conductor
overheating
6
Thermal fault of low temperature range
150C–300C
0 2 0 Local overheating of the core due to
concentrations of flux. Increasing hot
spot temperatures; varying from
small hot spots in core, shorting links
in core, overheating of copper due
to eddy currents, bad contacts
7
Thermal fault of medium temperature
range 300C–700C
0 2 1
8
Thermal fault of high Temperature >
700C
0 2 2
11
12. IEEE Method (Doernenburg Ratio Method)
• This method utilizes the gas concentration from ratio of CH4/H2, C2H2/CH4,
C2H4/C2H6 and C2H2/C2H4.
• at first value must exceed the concentration L1.
Key Gas Concentration L1 (in ppm)
Hydrogen (H2) 100
Methane (CH4) 120
Carbon Monoxide (CO) 350
Acetylene (C2H2) 35
Ethylene (C2H4) 50
Ethane (C2H6) 65
12
13. IEEE Method (Doernenburg Ratio Method)
• According to IEEE Standard C57.104-1991, the step-by step procedure to diagnose faults
using Doernenburg ratio method is:
Step 1: Gas concentrations are obtained by extracting the gases and separating them.
Step 2: If at least one of the gas concentrations (in ppm) for H2, CH4, C2H2, and C2H4
exceeds twice the values for limit L1 and one of the other three gases exceeds the values
for limit L1, the unit is considered faulty; proceed to Step 3.
Step 3: If at least one of the gases in each ratio CH4/H2, C2H2/CH4, C2H2/CH4 and
C2H6/C2H2 exceeds limit L1, the ratio procedure is valid. Otherwise, the ratios are not
significant, and the unit should be resample and investigated by alternative procedures.
Step 4: Assuming that the ratio analysis is valid, each successive ratio is compared to the
standard values.
Step 5: If all succeeding ratios for a specific fault type fall within the values (column) given
in Table 1, the suggested diagnosis is valid.
13
14. Fault Diagnosis for Doernenburg Ratio Method
Suggested Fault
Diagnosis
Ratio (R1)
CH4/H2
Ratio (R2)
C2H2/C2H4
Ratio (R3)
C2H2/CH4
Ratio (R4)
C2H6/C2H2
Thermal
Decomposition
>1.0 >0.1 <0.75 <1.0 <0.3 <0.1 >0.4 >0.2
Corona (PD) <0.1 <0.01 Not Significant <0.3 <0.1 >0.4 >0.2
Arching 0.1<R1<1.0 0.01<R2<0.1 >0.75 >1.0 >0.3 >0.1 <0.4 <0.2
TABLE 1
14
15. Fault Detectability Using Dissolved Gas Analysis
• The majority of faults are slow to develop, which can be detected by DGA
monitoring.
• Locations of faults detectable using DGA as reported by CIGRE are:
1. Within a winding.
2. Cleats and leads.
3. In a tank.
4. A selector switch.
5. A core.
• However, instantaneous faults are rapid and sometimes cannot be predicted by
DGA. Instantaneous failures that cannot be prevented by DGA are:
1. Flash over with power follow-through.
2. Serious failures, developing within seconds to minutes and therefore not possible to be
detected using DGA.
15
16. Combined Criteria for Dissolved Gas Analysis
• A combined DGA criteria, which are rooted on the guidelines from IEC, IEEE and the
new modification recommended by CIGRE Task Force 15.01.01
1) Detection and Comparison:
a) Detect concentrations and gassing rates of any gases dissolved in the oil, and compare
them with ‘‘normal’’ quantities using appropriate guidelines.
b) CIGRE TF 15.01.01 has set up a table with typical values for the key gases H2, C2H2, the
sum of the C1- and C2-hydrocarbons and the sum of CO2 and CO for generator and
transmission transformers as shown in Table 2.
c) Attention should also be paid to CO and CO2 when it is suspected that cellulose
materials are involved.
d) Additionally, a new ratio C2H2/H2 is introduced by CIGRE TF 15.01.01 to determine
whether fault gases diffuse into a tank from a leaking OLTC or not.
e) When an internal fault is suspected, the gas ratio methods and the key gas method
should be combined to identify the type of faults.
16
17. Key gas
Key gas concentration
(ppm)
Suspect of indication
C2H2 >20 Power discharge
H2 >100 Partial discharge
CxHy (x=1,2) >500 Thermal Fault
COx (x=1,2) >10000 Cellulose degradation
TABLE 2. Typical Values Of Key Gases For Generation And Transmission Transformers
17
18. Combined Criteria for Dissolved Gas Analysis
2) Assessment: Based upon the combined assessment results using various
DGA guidelines, further inspections should be carried out to identify the
type and location of faults, such as tests of no-load characteristics of
winding DC resistance, insulation, partial discharge and humidity content
measurements.
3) Action: Recommended actions should be taken, such as increasing
surveillance, shortening sampling intervals, reducing the load on the
transformer and finally removing the unit from service.
18