insulating materials: analyses and their application for

TRANSFORM Partner

Dr. Jürgen Schübel

Messko GmbH

Insulating Materials: Analyses and their application for transformer and tap changer monitoring

06.06.2013 Dr. Jürgen Schübel, Messko GmbH

Personal Introduction

Name Dr. Jürgen Schübel

Age 49

Studies

1983 – 1989

1989 - 1991

Chemistry at Ludwig-Maximilians-

University, Munich

PhD – Thesis at Max-Planck-

Institute for Polymer Research,

Mainz

1991 - 2011 Work at a Mineral Oil Company,

Refining

Since 2011 Head of Basic Development, Oil

Laboratory and Diagnostics at

Messko Instruments, Oberursel

Email [email protected]

1. Oil and paper degradation processes

2. Analyses for monitoring these degradation processes

3. Data interpretation for transformers and tap changers

4. Online analysis systems

5. Conclusion – Integrated Control System


Agenda


Degradation processes – Mineral Oil

C C

C C

C C

C C

corr

osiv

e p

rocess

degra

dation p

rocess

+

O-O . C

C C

+

OH

CHO

O

C C

C

C C

C

C C

C

COOH C C

C

+ COO - H+

C C

C Corrosion

+

C C

C C

C

H2, CH4, C2H2, C2H4, C2H6 C

C C

C C

C C

C C

C C

Oil Sludge

+

Ch

em

ica

l ca

taly

tic p

roce

ss

Energ

y „

inp

ut“

pro

ce

ss

Chemical high reactive

intermediate products

Acid value


Degradation processes

reduction of oil quality (carbon + ketones)

fast reduction of depolymerisation value (DP)

chemical reaction water + acid

reduction of oil quality (water + gases)

carbonisation of paper

oxidative / hydrolytic depolymerisation

low activation energy This aging process you will also find

in deenergized transformers in the presence

of oxygen and moisture

thermal depolymerisation

high activation energy

chemical reaction

chemical reaction

oil dissolved gases

alcohols, acids

oil sludge

cellulose carbon monoxide CO

carbon dioxide CO2

dissolved glucose rings

oxidation water

acids

ketones

(carbon bounded molecules)

hydrolysis dissolved glucose molecules

Oxidative Hydrolysis water + acids + oxygen Pyrolysis temperature

Ambient 118°C 150°C 100°C 105°C 75°C - 98°C

water water


Analyses methods

DGA

Color Index

Interfacial Tension

Moisture

Breakdown Voltage

Solids

Neutralization number / Aciditiy

Impurities

Furane analysis

Degree of polymerisation (DP)


Data Interpretation – Chemical and Electrical Parameters

Propert y Categor y a Recommended

action limits

Good Fair

Poor

Recommended action b, c Notes

Colour and appearance All Clear and Dark

and/or without visible

turbid

contamination

As dictated by other tests Dark colour is a symptom of chemical

contamination or ageing.

Turbidity is a symptom of high water content

Breakdown voltage (kV) O, A, D > 60 50 to 60 <

50

Good: Continue normal sampling.

Fair: More frequent sampling. Check other

parameters, e.g. water, particle content and

perhaps DDF/resistivity

and acidity.

Poor: Recondition the oil (see 11.2) or,

alternatively, if more economical

because other tests indicate severe ageing,

replace (see Clause 12) or reclaim (see

11.3) the oil combined

with subsequent drying procedures

B, E > 50 40 to 50 <

40

C > 40 30 to 40 <

30

F < 30 kV for OLTC in star-point

appl ication.

< 40 kV for OLTC in delta

or l ine-end appl ication

G < 30

W ater content (mg/kg at

transformer operating

temperature)

O, A < 15 15 to 20 >

20

Good: Continue normal sampling.

Fair: More frequent sampling. Check other

parameters e.g. breakdown

voltage, particle content and perhaps

DDF/resistivity and acidity.

Poor: Check source of water,

recondition the oil (see 11.2) or,

alternatively, if more economical

because other tests indicate severe ageing,

replace (see Clause 12) or reclaim (see

11.3) the oil combined

with subsequent drying procedures,

although regard should be taken of the quantity

of water that will sti l l be

retained in the solid insulation

The values of water content shall be always

regarded together with the values for breakdown voltage. In

case of a suspicion of a moisture

problem, sampling at different equipment

temperatures is recommended.

In case of switching equipment without paper

insulation (Category F), the values of breakdown voltage are

of overriding importance.

The listed l imit values represent 90 % statistical values and

are valid for transformer operating

temperatures. The equilibrium between sol id and liquid insulation under 40 °C is not rel iable and for heavy loaded

transformers with oil temperature

over 70 °C an implementation of the correction procedure

described in Annex A may be useful.

B, D < 20 20 to 30 >

30

C, E < 30 30 to 40 >

40

F Action

necessity > 40

G Not a routine test

Table 5 – Application and interpretation of tests (1 of 4), IEC 60422 - 2013

Data Interpretation – DGA / Transformer

Key gas ratio acc. to Rogers


Key gas ratios according to

Rogers

Principal gases

Key gas ratio acc. to Doernenburg

Source: IEEE C57.104


Data Interpretation – DGA / Transformer

Duval Triangle acc. to DIN EN 60599


Data Interpretation – DGA / Tap Changer

generated by CIGRE Working group D1.32 (disbanded); see Final Report: CIGRE Brochure 443

Examples:

– GE LRT-72, McGrawEdison 550, Westinghouse UTT, UTS :

– Reinhausen OILTAP® M, ABB UCG :

– Reinhausen VACUTAP® RMV-II, GE LRT-200..700 :

– Reinhausen VACUTAP® VR series, VACUTAP® VM :

AXC

ARS

VXC

VRS


Data Interpretation – DGA / Tap Changer

R

VAC

Classification:

VRS

H2 C2H2 CH4 C2H6 C2H4 CO

H2 C2H2 CH4 C2H6 C2H4 CO

bar

rier

bo

ard

transformer tank selector tank

Heating Pattern <300°C

Sparking Pattern

Very low absolute ppm levels

Temperature

mechanical thermometers

bellow type

type with Bourdon spring

Moisture

systems based on capacity measurement

DGA

gaschromatographic systems (5 to 9 gases)

IR spectroscopic systems (3 to 9 gases)

photoacoustic systems (up to 9 gases)

systems based on semiconductive metal oxides sensors (1 to 2 gases)

systems based on fuel cells (1 gas or sum of gases)


Online Analysis Systems


Integrated Control System - Summary

Integrated Control System

Laboratory Analysis

• Break down voltage

• Interfacial tension

• Furane analysis

• …

Online Analysis

• DGA (2 to 5 gases)

• Moisture

• Temperature

with easy-to-use and

robust systems

Specific Knowledge

•Transformer

•Tap Changer

• Chemistry

• Physics

• Data evaluation

Laboratory

Online

Knowledge

• Integration of laboratory and online data together with knowledge

leads to enhanced operational safety and projectable maintenance

in a short period of time

• Together with additional qualification of the staff cost reductions

and longer life cylce times can be expected in a medium period of

time

• Collecting many data of normal and failure operation leads to big

data basis generating increased knowledge, better analyses and

data interpretation and enhancement of standards.

Dr. Albert Hauser founds the company

Concentration on radiator thermometers for motor vehicles

First thermometer with bourdon tube

The brand was born

Main focus on industry/plant engineering

First thermometer of Compact Series

Start of Oil Level Indicator Series

Messko moves to new location

Becomes the subsidiary of Maschinenfabrik Reinhausen

Market introduction MESSKO® MPreC© and MESSKO® MTraB©

New Messko works in Oberursel

New Flow Indicator MESSKO® MFloC® will be launched

100th anniversary

Introduction MESSKO® MSafe® Buchholz Relay and MESSKO ® MLog®

06.06.2013

Messko Instruments

Foundation of Messko Nordic in Sweden

1911

1922

1932

1935

1954

1960

1975

1989

1999

2003

2008

2010

2011

2012

Dr. Jürgen Schübel, Messko GmbH


Thank you for your attention !

1. M. Duval: “The Duval triangle for Load Tap Changers, Non-Mineral Oils and Low temperature Faults in Transformers“, IEEE Electrical

Insulation Magazine, 0883-7554/07, 2008

2. P.Birkbeck et.al.: “Electric Arc Furnace Tap Changers – A Multifaceted Approach to Improving the Reliability and Performance of EAF On-

Load TapChangers“, AISTech Pittsburgh, 2010

3. Final Report of CIGRE WG D1.32: CIGRE Brochure No. 443, Dec 2010

4. IEEE PC57.139: “Draft Guide for Dissolved Gas Analysis in Transformer Load Tap Changers”,

D16, Oct 2010

Literature

T H E P O W E R B E H I N D P O W E R .

www.reinhausen.com

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