Dissolved Gas Analysis & Monitoring-GE

Digital Energy

05 June 2013, Argentina

Dissolved Gas Analysis & Monitoring

Technology, Products and applications

GE Monitoring & Diagnostics

June 2013 Donal Skelly

Introduction & Monitoring

Two factors are important to assess transformers:

Dissolved gas

The change in gas concentration

This may be indicative that there is an active fault. If concentrations are changing faster than normal aging would result in, a fault may be present.

The change in relative gas concentrations

If gas concentrations or gas concentration changes indicate that there is a fault a look at the relative concentrations of one gas to an other can be used to diagnose the nature of the fault

Moisture content

The relative saturation level of moisture in the oil

As a general rule, for every doubling of moisture in oil (and my inference moisture in the paper) the life of the transformer will be halved. Additionally increased moisture exposes the transformer to increased risk of short circuit

6/5/2013

Periodic testing

If a customer does not have on-line monitoring the only way to verify a transformer is to

perform periodic off line DGA and moisture analysis. This involves:

• Manually collecting 2 separate oil samples from the transformer and ship to a

laboratory.

• Wait for analysis (several days normally) • Laboratory GC for analysis of dissolved gas.

• Karl Fischer titration for determination of moisture content.

You then compared the measured values with the values from previous tests looking for any

increase and for the trend of this increase.

Disadvantages of periodic testing: • Periodic testing is not without cost: it takes time, ties up workers and requires

the transformer to be drained of some oil.

• Because of the requirement to visit the transformer to collect the sample, tests are generally carried out only every 1 to 2 yrs.

• It is performed on a sample that is normally several days removed from the condition when the sample was collected resulting in possible loss of sample integrity.

• Significant or even critical transformer faults can develop in a fairly short period time and in between annual offline tests check. Periodic tests will not detect quickly progressing problems.

On-line dissolved gas analysis systems can now continuously monitor dissolved gas content and relative saturation of moisture, detect developing faults at an early stage, enabling to schedule an outage for maintenance /replacement and prevent a catastrophic failure from occurring

Why do on line Monitoring

Dissolved Gas Analysis (DGA) is the industry defacto standard for transformer main tank and tap changer health assessment.

• Normal paper aging indicated by slow rise in CO2 – Accelerated or abnormal aging indicated by rapid rise in Carbon Monoxide

• Local low temperature hot spot indicated by rise in CH4

• Local High temperature hot spots indicated by rise in C2H4

• Detection of increasing quantities of Acetylene show arching occurring within transformer.

• Rules available to allow for quick and accurate determination of the presence of a fault and the nature and severity of that fault

Why Dissolved Gas Analysis?

GE Multigas Products - History

o Product line developed by a private company named Kelman

o Kelman looked at all available technology for measurement of gas and for gas extraction from oil.

o Decision was to employ Infra-red spectroscopy and headspace gas extraction. Many reasons why.

o All multigas products now based on these two core techniques.

o Kelman went on to dominate the market for multigas DGA – were acquired by GE in 2007

o GE product are now market leader in almost every country global and are overall global leaded for online monitoring.

GE Multigas DGA Products

TRANSPORT X* • Portable DGA

• 7 fault gases + moisture

• Simple & reliable

TRANSFIX* • Full 8 gas +

moisture on-line DGA

MINITRANS* • Cost-Effective on-line DGA

• Discrete gas measurement

(H2, CO, C2H2 + H2O)

MULTITRANS* • Full 8 gas multi tank DGA

TAPTRANS* • Full 8 gas on-line DGA for

main tank & LTC in one

unit

All based on Photoacoustic Spectroscopy and Headspace gas extraction

Photoacoustic Spectroscopy

Photoacoustics - Basics

• Photo-acoustic affect discovered by A. G. Bell

• Measures individual gas in a mixture without physical separation.

• Spectral domain identification

• Photo-acoustic effect quantification

• No carrier gases - operates in ambient environment.

Photoacoustic Spectroscopy - History

– 1960s environmental monitoring (CO, NOx, SOx)

– 1970s Operating theatre (Nitrous Oxide, CO2)

– 1990s Auto and construction industry (Sox, Nox, CO, CO2, H20, Hydrocarbons)

– 2000s Dissolved Gas Analysis - KELMAN (CO, CO2, CH4, C2H2, C2H4, C2H6, H2O)

– 200,000 PAS based detectors worldwide for all the above application, and others

– There are 7000+ GE PAS instruments worldwide

What is IR

Infrared absorption

• Almost every compound in the universe will absorb IR energy

– Every compound in existence has a unique absorption profile – like a finger print.

– If we target a region of the IR energy spectra that is unique for a compound we can measure its concentration.

– For DGA application, compounds are all simple gases

Photo-Acoustics – Basic Components

• Radiation Source at approx 900oC.

• Chopper pulses radiation at 29.5hz

• Filters optically distinguish one gas in a mixture.

• Sample sealed in analysis chamber.

• Microphones measure intensity of pressure pulse.

Acoustic Intensity + Filter selected = Gas Concentration (ppm)

Evolution of Photoacoustic Signal

START: Optical IR

Absorption

Heating of gas

Thermal expansion of

gas

Pressure waves

END:

Acoustic detection

Simple IR Spectrum – CO2

Photoacoustic IR Filters

IR-light pulses Sound wave proportional to gas

concentration

GAS

Photo-acoustic affect discovered by A. G. Bell Measures individual gas in a mixture without physical separation. Spectral domain identification Photo-acoustic effect quantification Employs one detector and no carrier gases Operated in ambient environment.

PAS Layout

DGA Gases Spectra – Simple broad absorption peaks

DGA Gases Spectra

#5 methane CH4 #0 water

#2 CO

#1 CO2

#4 ethane C2H6

#6 acetylene

C2H2

# 3 Ethylene

C2H4 LW

# 8 Ethylene

C2H4 SW

Full Spectrum & Filter positions for DGA

IR-active vib modes (rough guide)

#5 methane CH4 #0 water

#2 CO

#1 CO2

#4 ethane C2H6

#6 acetylene

C2H2

# 3 Ethylene

C2H4 LW

# 8 Ethylene

C2H4 SW

Full Spectrum & Filter positions for DGA

IR-active vib modes (rough guide)

Where are Hydrogen, Nitrogen and Oxygen?

Benefits of PAS

•No regular calibration or maintenance required

•No costly consumables such as calibration or carrier gases

•Capable of measuring at very low detection levels (e.g. 0.5ppm for acetylene) and very high detection levels (>50,000ppm)

•Capable of measuring individual gases in a mixture

•Ability to move from high gas levels to lower gas levels without cross contamination (TRANSPORT X, Tap TRANS

•Direct measurement of both CO & CO2, vital gases for understanding cellulose condition, giving increased accuracy & repeatability

User Benefits of choosing PAS

•Minimal maintenance required so not an O&M burden – with no ongoing support costs of either parts or labor

•Through rugged technology, repeatability is enhanced – this is vital for online monitoring as it is trend changes we are looking for

•Ability to monitor both multiple compartments (TapTrans) and multiple tanks (MultiTrans)

•No requirement for carrier or calibration gases – these can be expensive and difficult to transport

Gas Extraction from oil

Gas Extraction Techniques

• No technique allows for measurement of the gas while it is still a component of the oil.

• The gas must be removed from the oil or a representative sample of it removed prior to analysis.

• After removal the gas is passed to the detector eg, GC, PAS, solid state sensors etc.

Gas Extraction by online monitoring equipment

• All online equipment use headspace technique for gas extraction.

• Coil = Cgas X Partition Coefficient x Volumetric Ratio

• A membrane is a type of headspace extraction

• but there Is no volumetric ratio to consider

• GE use headspace as laid out in ASTM 3612 : Standard Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography.

Transfix Plumbing Basic

Transfix Plumbing Visualisation

TRANSPORT X Schematic

Products

What is it?

An on-line system that continuously monitors: • The concentration of 9 key gases in the

insulating oil of electrical equipment. • The concentration of moisture in

insulating oil. • Optionally transformer load and tank

temperatures around others

It will alert personnel of fault conditions at an early stage and provide vital health information on the transformer or tap changer.

TRANSFIX

Product Summary

Differentiated Value

• An integrated solution from a sole supplier.

• When the TRANSFIX is integrated with a BMT 300 bushing monitor unit, GE can offer a unique all-in-one solution that provides a more in-depth view of the transformer's health

• Enabling more condition based maintenance, resulting in reduced maintenance costs.

What does the TRANSFIX measure

Using separate oil collection and return point for

sampling, TRANSFIX can collect a discreet

representative oil sample up to once every hour for

analysis

• DGA: Measurement of 9 key gases

o Hydrogen

o Methane

o Ethane

o Ethylene

o Acetylene

o Carbon Dioxide

o Carbon Monoxide

o Oxygen

o Nitrogen

• Oil moisture analysis

o Moisture (ppm)

o Relative Saturation

DGA is measured as follows:

Oil pumped through the TRANSFIX unit, past an oil immersed Oxygen and Moisture sensor and on to fill a sample chamber to a predetermined volume. Gas extracted out of sample in sample chamber and analysis of this gas using a photo-acoustic gas analyzer

Moisture is measured as follows:

Oil flows over a capacitance moisture sensor and during sampling and together with oil temperature (if recorded) ppm and RS are determined

TRANSFIX – View of an Installed Unit

TRANSFIX – Complete DGA

Real-time Online DGA

8 gas + moisture analyser

Hourly Measurements*

Extensive communication/alarm options

No consumables or calibration

6 Analog Inputs, 3 Digital inputs

Full PERCEPTION integration

Can be upgraded to include fibre optic temperature sensors

TRANSFIX – Technical Specifications



Oil Manifold: 1. Takes oil sample from

Transformer 2. Extracts Gas from oil

PGA: 1. Performs measurement

on extracted gas

System Board: 1. Provision of I/O 2. Provision for communications

modules

Host Board: 1. Controls unit measurement

scheduling 2. Stores records

Simplified Overview of TRANSFIX

MINITRANS is similar - simplified manifold, PGA & system board

Standard • Two separate channels for remote

communications, local USB connection and Ethernet connection.

Protocols supported • MODBUS®, • MODBUS/TCP, • DNP3.0, • IEC61850®. Modules options available for connection • RS232, RS485, • Ethernet, PSTN modem and GSM or

CDMA wireless modems. • 16 channel 4-20mA analogue output

TRANSFIX Communications options

(All options are mounted inside TRANSFIX enclosure)

Fiber Convertors available

• Ethernet to Fiber, Singlemode

• Ethernet to Fiber, Multimode

• RS232 to Fiber, Singlemode

• RS232 to Fiber, Multimode

• RS485 to Fiber, Singlemode

• RS485 to Fiber, Multimode

TRANSFIX Communications options

(All options are mounted inside TRANSFIX enclosure)

TRANSFIX – View of Installed Units

MINITRANS – Cost Effective DGA

Real-time Online DGA

Measures

• Hydrogen

• Carbon Monoxide

• Acetylene

• Moisture



Load Sensor input





MiniTrans

PG

A

Simplified

PGA and

simplified

construction

Measureme

nt of:

H2

C2H2

H2O

CO

ΣCnHn

MULTITRANS – Multi tank DGA

Multi tank Real-time Online Transformer Monitoring

Monitors up to 3 separate single phase tanks









Oil Manifold: 1. Takes oil sample from



on extracted gas


modules



Simplified Overview of MULTITRANS

Oil Switching: 1. Selects tank

PGA

TAPTRANS – DGA for LTCs

Complete Online DGA for Transformer & Load Tap Changer

Monitors Main, Selector & Diverter tanks in one unit


Hourly Measurements







Oil Manifold 1: Main & Selector 1. Takes oil sample from



on extracted gas


modules



Simplified Overview of TAPTRANS

Oil Switching: 1. Selects Main or Selector tank

Oil Manifold 2: Divertor 1. Takes oil sample from


Failure Modes

Australia and New Zealand 457 failures over 10 years

0

5

10

15

20

25

30

Windings

Windings accessories

Core

Tap Changer

Motor driv

es parts

Bushings

Cooling

Others

%

0

5

10

15

20

25

30

35

Windings

Core

Tap Changer

Main tank &

oil syst.

Bushings

Auxiliarie

s

Others

ESKOM 1996 to 2006 136 severe and intermediate failures

%

CEA outages between 1997 to 2006

0

5

10

15

20

25

30

35

Bushings

Windings

OLTCCore

Leads

Cooling E

quipment

Auxiliary

Equipment

Other

%

Combining the 3 set of data along transformer elements

• Core and coils (including leads and winding accessory)

• Tap changer (including driving mechanism)

• Bushings

• Cooling system (including main tank)

• Others (including auxiliary components)

Relative importance of each component as a contributing factor

0

5

10

15

20

25

30

35

40

Core and

coils

Tap

Changer

Bushings Cooling

System

Other

Perc

enta

ge (

%)

Australia

Eskom

CEA


Complete Online DGA for Transformer & Load Tap Changer

Monitors Main, Selector & Diverter tanks in one unit


Hourly Measurements





Control room

Data transfer to control room

Reliable uninterrupted power is the lifeblood of many industries,

transformers are a critical tool in the production cycle

Solutions

Monitoring transformer health using TRANSFIX can reduce the

requirement for routine transformer maintenance and provide for

condition based maintenance and early fault detection.

TRANSFIX - Application Example

TRANSFIX Features & Benefits

Feature Benefit

On-line DGA Advance warning of Transformer needing maintenance/replacement

Enables Condition Based Maintenance (CBM)

Avoids catastrophic failure and /or transformer loss

Avoids need for routine visits to site and manual sampling

Early warning of possible arcing in main transformer tank

Tracks load current, moisture content and ambient temperature for advanced trending capabilities

Integration with MO150 (TRNSFIX Plus) Addition of models data for a more complete view of transformer internal faulth activity

Integration with BMT300 Bushing monitor Provides a complete transformer solution to effectively monitor

the majority of root causes of transformer failures.

Uses same PERCEPTION software to visualize data

Less vendors installing equipment in your switchyard

Single vendor integrated solution that works/communicates

• Combines TRANSFIX and MO150 in one enclosure

• Ethernet switch available for combined communications

• Will be integrated into PERCEPTION at next release (Feb 2011)

.

TRANSFIX Plus Online DGA with Models

.

TRANSFIX with BMT300

M&D’s Integrated Solution

The GE’s Intellix BMT 300 can easily be integrated with a GE’s TRANSFIX DGA analyzer, giving the end user a unique all-in-one solution that provides a more comprehensive view of the

transformer's overall condition: from bushing diagnostic and PD to complete main tank

monitoring.

Having an all-in-one GE integrated solution will significantly increase the ability to detect

potential transformer problems at an early stage, decreasing the risk of unplanned

downtime and improving asset reliability.

The integrated solution will provide:

o Developing key fault gases H2, CO, C2H2, C2H4, C2H6 as well as O2, CO2, CH4

o Moisture content in oil o Partial discharge activity

o Deterioration of the bushing insulating

All this information can be downloaded and visualized on the same PERCEPTION software as

with TRANSFIX, thus increasing familiarity and reducing learning curve.

Finally, the solution comes from a single supplier, ensuring reliable communication between

components and reducing the number of vendors working in the customer’s switchyard.

M&D Integrated Solution – Substation Application

BMT 300 – associated with

TRANSFIX multigas

Perception - Software

BMT 300 – standalone

Diagnostics

Main Tank 30%

OLTC 35%

Bushing 15%

Cooling System 5%

Others 15%

Main Tank: Windings failure, Partial Discharge, Excessive H2O, surface contamination, connection failure,

circulating currents, overloading hazard.

OLTC: contact overheating and coking, desynchronization, excessive number of operations, mechanical damage,

neutral switch inactivity

Bushing: moisture penetration, oil leak, partial discharge

Cooling System: clogged coolers by pollen or dust, fan/pump failure, sludge, oil leak

DGA can provide for detection of the majority of the above faults by tracking changing gas concentrations

or gas ratios

Other Failure Modes not detectable by on-line monitoring: External, such as lightning, animal interference,

operation error,

Location of Transformer Failure

Main tank

LTC

Bushing

Cooling system

Other

Transformer failure locations & modes

Key DGA gasses, and what they indicate

H2 Hydrogen Nearly all fault conditions, low energy PD

CH4 Methane Oil overheating between 200ºC and 500ºC

C2H6 Ethane Oil overheating between 300ºC and 500ºC

C2H4 Ethylene

Oil overheating over 500ºC, possible formation of carbon particles

C2H2 Acetylene High energy arcing, oil overheating over 800ºC, strong formation of carbon particles, metal melting

CO Carbon Monoxide Paper insulation overheating

CO2 Carbon Dioxide Oil oxidation, paper degradation

O2 Oxygen Oxidation, leak

Bushing – Power Factor

• Transfix is equipped with a direct connection, via USB

for data download capability

• Remote download available when utilizing one of the

various communication protocols

• TransConnect is used for Transfix settings and the

configuration of Alarm limits

Perception is used for data downloading and analysis of

DGA results to provide a diagnosis of the fault, if one is

detected

TRANSFIX – DGA for Fault detection

Utility value

Advanced Transformer Management Software • Specially designed for the power industry • Provides simplified trending • Provides advanced transformer diagnostics • Intuitive/configurable interface

What is Perception

6/5/2013

Utility value

What is Perception

• Shipped with Transfix unit • Designed for single user/local

database • Requires manual result

download • Recommended for low

number of DGA units

Enterprise version of Perception. In addition to Express features: • Multiple users • Central database • Scheduler (Console) for

automated results download • Email alarm notification

6/5/2013

Transformer Services

Transformer Field Services

Team of transformer design and test experts available to perform

• In-depth condition assessments • Condition based ranking of fleet • Design reviews • Training.

Our methodology uses extensive On-Line

testing. • test the transformer in its real life state. • less reliance on outages and less

disruption to the customer.

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