SPLN 49-1B_1982.pdf

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Publication22

. - _ v

Guide

our

amaintenance

des uilessolanles

et

asurueillance

en eruice

Maintenance

nd uperuision

uide

for nsulatingilsnseruice

Droits

e eproduction

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Bureauentrale aCommissionlectrotechniquenternationale

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7/23/2019 SPLN 49-1B_1982.pdf


R6vision de

la

pr6sente publication Revision

of

this

publication

L€ contenu technique des

publications

de

la CEI est cods- The techrdcal content of

IEC

publications

is kept under

tafiment revu

par

la Commission a.fin d'assure

qu'il

reflete constant

review by

the IEC, thus ensufing that the content

bien l'€tat actuel de 1a echnique, reflects current technology.

I-€s renseignements relatifs i ce travail de revision, i

l'6ta-

Information on

the

work of

revision, the issue

of

revised

blissement

des editions r6vis€es et aux

mises i

jour

peuvent

editions and amendment sheets may be obtained from IEC

etre obtenus auprCs des

Comitds nationaux de la CEI et en National

Committees

and

from the following IEC

sources:

consultant les documents ci-dessous:

a

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la

CEI

a

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publie

hime,striellement

Published

quarterly

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Report on IEC Activiti€s

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yearly

O

Catalogue d€s

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de

la

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O

Catalogue ofIEC

Publications

Publi6 annuellement

Published

yea y

Terminologie utilis6e dans a

pr6sentepublication

Terminology used n this

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Seuls sont deflnis ici les tetmes sp€ciaux s€ rupportant i Ia

ODly special telms required for the

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pr6sente publicatiotr. arc defined hereio'

Eo ce

qui

co[ceme

la

terminologie

g€n6rale,

le lecteur

se

For

geneml

terminology, readeN arc referred to IEC Publi-

reportera e h Publication 50 de la CEI:

Vocabulairc

Electro-

cation 50: International Electote.hnical Vocabulary

(I.E.V.),

technique

International

(V.E.I.), qui

est etablie sous

forme

de

which

is issued in the form

of

separate chapters each

dealing

chapibes

s€pards raitant chacun

d'un sujet defini,l'index

g6n€-

with a specific field, the GeneEl Index being

published

as a

ral 6tant

pubtd

s6par€ment. Des details complets sur le

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separate booklet. Full details of the

LE.V.

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Deuvent CtIe obtenus sur demande.

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es symboles

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this

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contained n IEC Publication 27.

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c 0 M M r s s r 0 Nt r c T R 0 T E c H N r 0 u EN T E R N A T t 0 N A L E

(affili6e

l'0rganisationnternationaleeNormalisationlS0)

R E C ( ) M M A N D A T I l l NEL A C E I

I N T E R N A T I ( l N A LL E C T H O T E C H N I C A L( ) M M I S S I ( } N

(aff i l iated

o the nternationalrganizationor Standardizati onlS0)

I E C R E C ( ) M M E N I l A T I ( l N

Publicalion

22

Premi i re

d i t ion F i rs t

d i t ion

1 9 7 3

Guide

our

des

lamaintenance

huiles

solantes

et a

surueillance

en

eruice

Maintenance

nd uperuision

uide

for nsufalingilsnseruice

PERP''ST

KAAN

IIMBAGA

r..rtriiol-r..

{ETF,I\IAGAAN

No.

Ageoda

qW

T a n g g a l

, 9

- - 9 -

Dro i ts

e eproduct ion

eserv6s

Copyr igh t

a l l iqh ts

eserved

Aucune ar t ie

e ce t t e

pub l r ca t ron

e

peu t

e t re

epr0 r lU i t e

i L r t i l i s6e

ous

No

par t

o f

t h rs

pub l i ca t r0n

ay

be reproduced

r

u t r l i zed

n any

que lque

orme

que

ce soi t t r t

pa r

aucun

procede ,

lec t ron iq r i e

u

mEca-

form

t r r

any

means ,

lec t r0nic

r mechan ica l ,

nc lud ing

ho t ocopy ing

n t que ,

compr is

a

pho t ocopre

t esmicrol i lms,

ans

'accord

cr i t e

' ic l i teur .

and

microf i lm,

i t hou t

e rm iss ion

n

wr i t ing

rom he

pub l i sher .

Bureau

entral

e

a

Commission

lectrotechnique

nternationale

1, ue

e

Varembd

6eneve,

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iii:Ji

,

34 0

7/23/2019 SPLN 49-1B_1982.pdf


- 3 -

CONTENTS

FonrwoRo

PnrnlcE

Clause

1.

Introduction

Scope

Oil deterioration

and recommended

ests .

3.1. Deterioration

of

oils

in

service

3.2.

Special ests

Frequency

of examination

of oils in service

Action to

be taken

Criteria

7. Test

methods

.

7.1.

Sampl ing

7.2.

Electric

strength .

7.3.

Water

content

7.4. Dielectric

dissipation

actor .

7.5. Resistivity

7.6. Neutralization

value

7.7.

Sediment

and

precipitable

ludge

7.8. Flashpoint .

7

9.

Interfacial

ension

7.10. Dissolved as

.

7 l l .

Co lour .

7.12. Appearance

7.13.

Oxidation stabil i ty .

7.14.

Compatibility

.

7.15.

Other field

tests

AppExorx

A1

-

Application to

oils in transformers

AppeNolx

A2

-

Application

to

oils in switchgear

Apprxolx B

-

General

procedure

or handling,

reconditioning

and

Frcung I

Page

)

5

2.

a

7

7

7

7

l 1

1 3

1 3

1 5

l 5

1 5

l 5

t 5

l 5

r 7

1 7

l 7

t 9

1 9

t 9

l 9

1 9

t 9

t 9

l 9

4.

5 .

6.

replacing

oi l

2 l

23

25

32

7/23/2019 SPLN 49-1B_1982.pdf


- 5 -

INTERNATIONAL

ELECTROTECHNICAL

COMMISSION

MAINTENANCE AND SUPERVISION GUIDE

FOR

INSULATING

OILS IN

SERVICE

FOREWORD

l) The

formal

decisions

r agreements

f

the IEC

on

technical

matters,

prepared

by

Technical

Committees

n

which

al l

the National

Committees aving

a special

nterest

herein

are

represented,

xpress,

s nearly

as

possible,

n

international

consensus

f opinion on

the

subjects ealt

with.

2) They have the form

of

recommendations

or

international

use and they

are acceptedby the

National

Committees n

that sense.

3)

In

order

to

promote

nternational

unification, he IEC

expresseshe

wish that

all

National

Committees hould

adopt

the

text

of the IEC recommendation

or their national

ules n

so

far

as national

conditionswill

permit.Any

divergence

between

he

IEC recommendations

nd

the

corresponding ational ules

should,as

far

as

possible,

e clearly ndicated

in

the

atter.

PREFACE

This

recommendation

has

been

prepared

by Sub-Committee

10A, Hydrocarbon

lnsulating

Oils, of

IEC Technical

CommitteeNo. 10,

Liquid and

Gaseous

Dielectrics.

The drafts

were

discussed uring the mee tingsheld

in

Tehran

in

1969

and

in Brussels

n

1970.

As a

result of this latter

meeting

a new draft,

document l0A(Central

Office)14,was

submitted to

the National

Committees or approval under the Six Months'Rule in October 1971.

The

following

countries

voted explicitly in favour

of

publication:

Australia

Poland

Austria

Portugal

Belgium

Romania

Canada

South Africa

Czechoslovakia

Srveden

France

Switzerland

Germany

Turkey

Israel

Union of Soviet

Italy SocialistRepublics

Japan

United

Kingdom

Netherlands

Yugoslavia

7/23/2019 SPLN 49-1B_1982.pdf


2.

- 7 -

MAINTENANCE

AND

SUPERVISION

GUIDE

FOR

INSULATING

OILS

IN

SERVICE

lntroduction

Many countries

possess

odes

or

the maintenanceof

insulating oils

in

service.

A comparative

examination

of

these documents

has

made it

possible

o

propose

an

International Guide.

The

values

of

the various characteristics

mentioned

therein

should be

consideredas

indicative

only.

In

fact, for

the

proper

interpretation of

results,

account

has

to

be

taken of various

factors,

such

as

the conditions

of use,

he type of eq uipment,

and

the

generalprogression

f

the

oil 's

charac-

terist ics.

Reference

hould

also be

made to the equipment

manufacturer's nstructions.

lt is

not intended

hat the

contents

of

this documentshould

give

he

full

detailsof

the instruc-

tions which are

necessaryo

deal

with all

types of oil-filled equipment

of all sizes.The

intention

is to give a common basis on which more complete codes may be prepared when these are

necessary.

In the

present

Guide,

the

causes

of oil

deterioration are discussed,

nd

recommendationsare

made

for

the various

tests. ndications

are also

given

regarding

the type

of

treatment

to

which

the

oil should

be subsequently

ubjected,

f

applicable.

Scope

This Guide

applies

o mineral oils, both

uninhibitedand

inhibited againstoxidation,

n

service,

under

normal operating

conditions,

n

transformers,switchgearand

similar electrical

equipment

where oil

sampling

is

permissible.

These oils

are of

the

same

type as

those

described

n IEC

Publication 296: Specification or New Insulating Oils for Transformersand Switchgear.

Application

of

the recommendationsof

this

document

to oil

in transformers of

low

power

or

voltage

<

I

MVA

or

{

36

kV)

may require

variation in the

light

of

local

economic

circumstances

(see

preliminary

remark

No. 2 in Appendix

Al).

Oil

deterioration

and recommended

ests

Deterioration

of oils

in

service

In

service,

nsulating

oils

are subject

to normal deterioration

due

to the

conditions

of use.

For example, n many applications the oil is in contact with the air. It is therefore subject to

oxidation

reactions

accelerated

y

temperature

nd

the

presence

f

catalysts

solid

ron and copper,

dissolved

metallic compounds).

As a

result, here

s

a change

n colour, and acid

products

are

formed. The dielectric

dissipation

factor may

increase

and,

at an advanced

stage

of oxidation, sepafation

of sludge

may

occur.

In certain

special

cases,

other

changes

n

the

characteristicsof

the oil

may

be

a sign of abnormal

deterioration

of certain

other

materials used

n the

construction

of

the

equipment.

All these

changes

may

affect

both solid

and

liquid

insulating

materials,

interfere with

the

proper

functioning of

the

electrical

equipment,

shorten ts

working

life

and,

n

some

cases,

ncrease

the no-load

osses.

3.

3 . 1

7/23/2019 SPLN 49-1B_1982.pdf


9 -

Any

kind

of deterioration

of

an

oil

is made

evident

by changes

n

one or

more

of the

character-

ist ics

mentioned

below.

The

appearance

f an

odour and a

change n colour,

although not

being of a decisive

nature,

may,

by

comparison, ive

useful ndications

about the trend

of c hange n

an oil.

The following contaminants nay be found in insulatingoils in service.

3 .1 .1

Wate r

Water

may

originate from

the

atmosphere

or be

produced

by the

deterioration

of insulating

materials.

ts

presence

s

harmful; it may

reduce he

electricstrength

and the resistivity

of

the

oil

and

accelerate

he

deterioration

of

insulatingpaper.

Irlote.

-

Resistivity

and

dissipation factor

are

adversely

affected by

undissolved water

and to a much lesser

extent

by water in

solution,

but a decrease

of

resistivity

may

sometimes

be observed

with no

appreciable rise

in

dissipation factor.

3.1.2

Solid

porticles

i.e.

sediment,

eeSub-clause

.7.)

Solid particlesmay be classif iednto four categories, ccording o their origin:

l)

Insoluble

oxidation

or degradation

roducts

of

solid or

l iquid

insulating

materials.

2) Deteriorationproducts

due to

condit ionsof service

f

the

equipment:

carbon, metal,

metallic

oxides.

3) Various

products

resulting

rom inadequate

leaning

of

the

equipment

before

being

put

into

service.

4)

Fibres

of diverse

origins.

The

presence

f these

particles

normally

reduces he

electricstrength

of

the

oil

and, in

addition,

deposits

hinder heat-exchange,

hus

encouraging urther

deterioration

of the insulating

materials.

3.

.3

Polar

substances

These

are oil-soluble

compounds

esulting

rom

oxidation

of

the

oil

itself,

or from the

solution

in the

oil of

external

contaminants

r materials

used n

the construction

of

the

equipment.

Measurements

f the

dissipation actor

and to a

lesser

extent,

resistivity

and

interfacial

ension

of the

oil

enable

such

contamination o

be detected

nd

periodically

assessed.

A

comparison

of th e rate

of changeof the neutralizatio n

alue with

that

of one

of

these hree

characteristics ives,

o some

extent, an

indication

of the

probable

cause

of the

deterioration

of

the

oil.

For

example,

a

high

value

of dissipation actor

associated

with a low

neutralizationvalue

may

sometimes

be considered

as an

indication

of

oil contamination

other than

of oil origin.

a) Dielectric dissipation

factor

This

characteristic

s

very

sensitive o the

presence

n

the oil

of solublecontaminants

and ageing

products.

Changes n

this

characteristicmay

be

monitored

evenwhen the

oil is heavily

con-

tarninated.

his

determination s

therefore

of special nterest.

b) Resistit,ity

For

any

given

oil,

there

s

generally

a

relationship

between

dissipation

actor

and resistivity:

if the

dissipation

actor

increases,

here is

a reduction in

resistivity.

Useful

additional

information

can be obtained

when it is

possible

o

do the

resistivity

est

at

both

ambient emperature

nd 90

"C.

A satisfactory

esult

at

90'C coupled

with

an unsatis-

factory

value

at

the

lower

temperature

s an indication

of

the presence

f water

or

cold

pre-

cipitable material,

without

undue chemical

deterioration

or

general

contamination.

7/23/2019 SPLN 49-1B_1982.pdf


3 . 1 . 4

3 . 1 . 5

3 . 1 . 6

3 . r .7

3.2

3 .2 . r

-

l l

-

Unsatisfactory

results

at both temperatures indicate

a

greater

extent of contamination than

a

poor

value at the lower

temperature

only, and that the

oil is

therefore

less likely to

be

restored o

a satisfactory evel

by

drying and

low

temperature iltration.

The

measurement

of

resistivity

can be

more

easily carried out on site than that

of dielectric

dissipation actor.

c) Interfocial

tension

This characteristic

changes airly rapidly

during

the

first stagesof ageing.Afterwards,

the rate

of change

decreases

s

the

values hemselves

ecome ower.

For this reason,

he results

are difficult to interpret

especiallywhen the

oil

is

heavily

con-

taminated.

Organic

acidity

The

acid

products

formed

by

the

oxidation of the

oil actively encourage

deterioration

of

insulating

paper

and

pressboard.

t is therefore

essential o

detect and

monitor

this

process.

The determination

of organic acidity

by

measurement

of the neutralization

value is the most

convenientand direct method of assessinghe chemicalageingof an oil. The presence f dissolved

COr in the

oil

(see

Sub-clause

.1.6.)apparently ncreases

his

acidity, but dissolved

CO,

content

is considerably

educed f

vacuum treatment

s

applied

to the

oil.

Precipitable

sludge

This

refers

to

sludge

which

is

precipitated

by

adding

n-heptane

o the

oil

but which may

be

subsequently

dissolved

by the solvent

specified n the test method

(see

Sub-clause

7.7.2.).

The

presence

of such a deposit,

consisting of

products

formed

at an advanced

stageof oxidation, is

undesirable

and

is

a

premonitory

sign of insoluble

sludge.

Dissolved gases

Under normal

service

conditions, the

production

occurs

of only small

quantities

of

CO,

CO,

and

very small

quantities

of hydrogen

and hydrocarbons.

Large

amounts of

dissolved

gases,

other

than

atmosphericcomponents,may

be

an

indication

of

an

incipient

fault in the

equipment.

Light

hydrocarbons

Light hydrocarbons

are formed during the

degradation

of oil

under the influence

of

heat,

and/or

electrical stresses.

arge

amount of

these

hydrocarbons

may

be

an

indication

of an

incipient

fault in the

equipment.

The

presence

f some ower hydrocarbon

deterioration

products

may

be detectableby measuring

he flash-point

of the

oil.

Special

tests

Oxidation

stability of

inhibited oils

Inhibited

oils

do

not

deteriorate

more

than slightly

as

ong

as

he active

nhibitor

is

still

present.

For

a

given

oil, the

induction

period

is

generally proportional

to the

active inhibitor

content,

provided

that the

inhibitor

has

been added

to

a

new

non-aged

oil. The

oxidation

test for

new

inhibited

oils enables

he induction

period

of

an oil

to

be

easily

measured

by

means

of determi-

nation

of volatile acids

developed.

This test,

applied to

a used oil

previously

tested,

will indicate to

what

extent the induction

period

has

been reduced.

7/23/2019 SPLN 49-1B_1982.pdf


t 3 -

3.2.2

Compatibility

of

insulating oils

Compatibility

tests may

be

required to deterrnine

he

feasibility of

mixing rrew oils of different

type

and

origin

or new oil with

oil

in

service,

f

the make-up is

more than

5\ .

These ests are of particular interest in the case of inhibited oils.

The

main characteristics

f

the mixture, including oxidation

stability,

must not

be

less avour-

able

than those of

the worst

individual oil.

4.

Frequency

of examination

of oils

in

service

This

dependson

the

power, loading, construction and other

service

conditions

of

the

equip-

ment.

Hence, it is

not

possible

o

lay

down

a

general

rule applicable

to all

types

of oil-filled

equipment.

By way of a

guide,

tables showing

the application and

frequency

of

tests

suitable

for

different

types

of equipment

are

given

in Appendices

Al and

42.

Generally,

check

measurements

an

be

carried out on

the basis

of

paragraphs

l),

2)

and 3)

below, which apply particulary to transformer oils:

1)

Check

periodically

characteristics,

t

intervals

as

suggested

n Appendix A1, unlessotherwise

defined by

manufacturer.

2) It desired,check at

more frequent

intervals

those

characteristics

eterminable on site.

3)

If rapid deterioration or acceleration

n the

process

of

deterioration

s observed, ecommend:

a)

to confirm

the last value by

means of a

further test

on

a

fresh sample;

b)

to inform the manufacturer of

the equipment;

c)

to

check

the

condition

of

the oil

rnore frequently,

according

o the

size

of the equipment

and

the

degree

of deterioration

observed.

As regards

oil

in switchgear, t

may

be

sufficient

to

check

the electric

strength either

periodically

or after a

given

number of operations.

5.

Action

to be taken

The

following casesare

considered as a

function

of

the degree of

deterioration

of the

oil:

a) The characteristics

re

normal: no action

is necessary.

b)

Only

the value of

the

electric

strength

is

too low:

remove

water and solid

particles

by

re-

conditioning (e.g. filtering, centrifuging or vacuum dehydrating) (see Appendix B, Sub-

clause83.2).

The efficacyof

the treatment should be

controlled.

In

casesof high

humidity

of

transformer

oil,

it may

be

necessary lso

to

dry

out

the insulation of

the

active

part

of

the transformer.

c)

One

or

more

characteristicsof

the oil change

rapidly:

supplementary

ests

of

the

oil

(see

Sub-clause

.3) .

d) Several

characteristicsare

unsatisfactory:

according

to

economic

factors

and

local circum-

stances,

t should be decided

to

examine

the oil more

thoroughly,

to

reclaim

the oil or

to

replace

t

altogether.

In

caseswhere

oil

is

reclaimed

or replaced,

the

equipment

should be

thoroughly flushed

before

refilling,

with special attention

to the

windings,

to

minimize contamination

of

the

new

oil by ageingproducts (Appendix B).

7/23/2019 SPLN 49-1B_1982.pdf


1 5 -

If

the

oil has

been eclaimed,

ts

characteristics

hould

be checked

and, f

necessary,

ts

oxidation

stability

should

be reinforced

by addition

of inhibitor.

The characteristics

of reclaimed

oil

should

be verified

after

addition

of

inhibitor.

if this

is

applicable.

It is

always

advisable

also to

carry

out a laboratory

test

before reclamation

of the

used

oi l

in order to ensure hat the treatment s appropriate.

Note-

General

rocedure

or reconditioning

f oil

by several

rocesses

s

given

n

Appendix

B.

A

guide

of

reclaiming

as

been

ublished

*

6.

Criteria

The values

of

perrnissible

lirnits

for the

different

criteria

listed

in

Appendices

Al

and

A2

are

given

for

guidance

only

and they

should

be interpreted

n

terms

of the

type

and

size

of the

apparatus.

Depending

on

such

type

and

size,not

all

of the

tests

given

n these

Appendices

need

to

be done.

As a generalrule, severalcharacteristics ave to be unfavourable n order to justify rejection

of

an oil

unless,

f

course, he

electric

strength

s

below the

limits given.

n

such

a case,

rrespective

of

the

values

of

the

other

characteristics,

ppropriate

action is

essential.

7.3

Test

methods

Sampling

Under

consideration

v IEC.

Electric

strength

See

EC Publication

156:

Method

for

the

Determination

of the

Electric

Strength

of Insulating

Oils.

Water

content

See

SO

Recommendation

R

760.

Note.-

Temperature

f

the

oil and transformer

perating

onditions

must

be noted

at the

time

of sampling

(see

EC

sampling

nethod).

D e

ect

ic

dissipation

actor

See EC

Publication

250:

Recommended

Methods

for the

Determination

of

the

Permittivity

and Dielectric

Dissipation

Factor

of Electrical

Insulating

Materials

at Power,

Audio

and Radio

Frequencies

ncluding

Metre

Wavelengths,

and IEC

Publication

247:

Recommended

Test

Cells

for Measuring

the

Resistivity

of

Insulating

Liquids

and Methods

of

Cleaning the

Cells.

Carry

out the measurement

at

90

"C

and

power

frequency.

7"

7.1

7.2

7.4

*

See

IEEE

Guide

for

Acceptance

and

Engineers

March 1969

(IEEE

No.

Maintenance

of

Insulating

Oil in

Equipment

".

Inst.

of

Elestrical

and Electronics

64),

7/23/2019 SPLN 49-1B_1982.pdf


7 .5

- t 7 -

Resistit,ity

See EC Publications

3 Recomntertded

ethods

of

Test

or

Volume

and SurfaceResistivities

of Electr ical

nsulat ing

Mater ia ls,

nd IEC Publ icat ion24T.

Carry

ont

the

nteasurement

t 90

C

after

a d.c. voltage

gradient

of 250

V/mm has

beenapplied

for one minute.

l''lote.

Another

cmperature

ay

bc

chosen.

See

elationship

resistivity-ten-rperatLlrc",

igurc

1,

page

32.)

Netrtralization

yalue

See EC

Publ icat ion

96,

Clause l .

Sedinrcnt

antl

precipitable

sludge

7.6

7 .7

7 .7 .1

Scope

This

method

covers

he

detemrination

f

sediment

nd of

precipitable

ludge n

used nsulating

o i ls .

Sediment:

any

solid

substauce

hich is insoluble

n the

oil after

dilution with

n-heptane

an d

in the

solvent

mixture

mentioned

below.

Precipitable

sludge;

oil

deterioration

prodircts

or contarrir-rants,

r

both, which

become

insoluble

uporl

di lut ion

of

the

oil with

n-heptane

under

prescribed

onditions

but which

ar e

solr , rb le

n the

hereunder-ment ioned

olvent

nixture.

7.1.2

Procedure

Thoroughlyagitate he satttple f usedoil in the originalcontainer .rntil ny sedinelt is homo-

gerreously

uspended

n the

oi l .

Weigh

approximatively

0

g

of

oil

to the

nearest

,1 g,

in

a stoppered

onical

lask

apd intro-

duce

a volutne

of n-heptane

orresponding

o l0

nrl for

each

granrme

of

oil

taken.

Tl-roroughly

mix

the

sarnple

lnd solvent

and

allow to

stand l-r

he

glass

lask,

n

the

dark, for

18-24

hours.

If

er

olid deposit

s

observable,

i l ter the

solution

hrough

a

tared

Grade

4

sintered lass

rucible

with the

assistance

f

vacuum,

insing

he

flask

with lresh

n-heptane

o

ensure

omplete

ransfer

of

the precipitate

o

the

crucible.

Wash the

crucible

ar-rd

recipitate

with heptane

until

free

rom

oil.

Allow

any heptane

o

evaporate

nd

then

dry

the

crucible

n

an

oven

at 100-110

C

for

one hour,

cool

in

a desiccator

nd

weigh;

calculate

he increase

n

weight

of the

crucible

as a

percentage

of

the

weight

of

oil

taken.

Denote

his

value,

epresenting

he otal

of

insoluble

material

suchas a

sedirrrent

nd

precipitable

sludge,

as

"A".

Dissolve

he

precipitated

sludge

n the

crucible

by treatrnent

with the

rninirnum quantity

of

a

Irlixtttre

of equal

parts

of toluene,

acetone

and alcohol

(either

ethanol

or isopropapol

nay

be

Itsed.

a

purity

of

95

being

satisfactory

n

either

case),

at approximately

50

'C,

until no

more

n'ill

dissolve,

ud

collect

he

washings

n

an

accurately ared

flask. Disti l

offthe

solvent;visual

exatninatiotr

f the

flask

coutent

at this

stage

will

show

whether

any residue

i.e.

precipitable

sludge

n

1he

oi l )

is

present.

This n-ray

ltf f ice;

f however

a

quantitative

alue

s reqr-rired,

ry

the

flask

n

an

oven at 100-

ll0'C

for

one hour,

cool

in

a

desiccator

nd weigh.

Calculate

he

weight of residue

n the

flask

as a

percentage

f the

weight

of oil taken.

Denote

such

value

as

"8".

The difference A-B", if any, will represent sediment" n the oil.

7/23/2019 SPLN 49-1B_1982.pdf


- 1 9 -

7.8

Flash point (closed

cup)

See

EC

Publication

296A:

First

supplement

o Publication

296

(page

25).

Field

test:

suitable

equipment

s

commercially

available.

7.9 Interfacial tension

See

EC Publication

296,

Appendix.

Field

test: interfacial

tension

of

electrical

nsulating

oils

of

petroleum

origin

against

water

may

be determined

more

easily

n

the

field

by the

drop-weight

method.*

7.10

Dissolved

gas

Under

consideration.

7. l l

Colour

Any

applicable

National

Standard

or

petroleum

products

may

be

used.

See SO Recommendation S 2049.

7.12

Appearance

See EC

Publication

296,

Clause

6.

7.13

Oxidation

stability

Uninhibited

oils:

see

EC

Publication

74: Method

for

Assessing

he

Oxidation

Stability

of

Insulating

Oils.

Inhibited

oils

under

consideration.

7.14

Compatibility

The

main

characteristics

ncluding

oxidation

stability

are

determined

on

a

mixture

of

the

new

oil

and the

used

oil.

The ratio

of this

mixture

is

the

same

as that

effectively

chosen

n

practice.

If this

ratio

is

not

known

at

the

laboratory,

ests

are to

be

made

with

a mixture

containing

one

part

of

new

oil

and

one

part

of

used

oil.

7.15

Other

field

tests

See

eference

n

footnote,

page

15.

*

As examplea descriptionof this method is given n ASTM Method D 22g5-6g.

7/23/2019 SPLN 49-1B_1982.pdf


a

d

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c F *

O

: : F :

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6 p 9

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lr

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r-.

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8

' E g

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+ E E ' F E _ E

; e i - - E F a . i

E o . E i o ' H

. F F

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E *

f r A z r ,

3 € ; : s €

E i

i

f i 9

=

h # e c

z y , x E 3 ; t r

E E

6

L

()

'o

()

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q)

)

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bi

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oo

tr

(.)

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q-1

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n

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l c o E - H - f " a

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t r t

a

a

q.)

(*

O

c)

C)

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a.)

a

0)

ho

00

a

o c )

t r o o

x t r

6 >

tll

L)

(t)

tr

0,)

()

tr

Q

F . J

- 2 1

-

a

I r l

Y A

p n

a i

z ;

s z

i <

Z Q

= <

o F

z Q

a \ <

o

? > )

F l l

4 ' a z

\

F O

X

i n

l + A

A' n

v

Z z 3

x r 9 ,2

H

H 3

= < F

1 - x ,

7 0

I

A -

/1. \)

F

. - l

r r \ H

\

fr

Fr

L

r- i

r-7

*1

Fi.

A

^ ( ,

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=

7/23/2019 SPLN 49-1B_1982.pdf


- 2 3 -

APPENDIX A2

INTERPRETATION OF TESTS ON OIL

IN SWITCHGEAR

AND ASSOCIATED APPARATUS *

Characteristic

measured: Electric strength

Testmethod: IEC 156

Test

venue:

Field or

laboratory

Equipment voltage

Breakdown

voltage

equired

Permissibleimit:

>l7okv

>

30

kv

<

l70kv >

20kv

Frequencyof

test: Seemanufacturer's

specification

Action

if

outside

permissible

limit: Reconditioning r

replacement

f

the

oil.

t

Excluding ap changeequipmentof

power

transformers.

7/23/2019 SPLN 49-1B_1982.pdf


8 1 .

- 2 5 -

APPE,NDIX

B

GENERAL

PROCEDURE FOR

HANDLING, RECONDITIONING

AND

REPLACING

OI L

Scope

The scope

of this appendix is

to

give general

principles

that can

be applied

to

l-randling,

e-

condit ioning

and

replacingof insulatingoils.

The

general

naintenanceules

o

be

followed may

be

found

either

n

IEC

publications

ssued

by

those Committeesdealing

with

a

given type

of

equipment,

or in manufacturer's nstructions.

The

rnain

precautions

o

take in handling, replacing and

for

processing

o improve charac-

terist icsof the oil are described.

There are

two types

of cleaning

processes:

a)

Reconditioning:

This

involves

a

process

o elirninate, nly by

physical

means,

olid

particles

rom the

oil and

to

decrease

water content to an acceptable

evel.

b) Reclaiming:

This involves a

process

o

eliminate

rom the oil al l contarninants,

nsoluble

and

dissolved,

to obtain, at

the

end

of

the

process,

n oil

with

similar

characteristics

o those chosen

or

the new

product.

In this appendix,only the caseof " Reconditioning will be exarnined. he applicabilityof

the " Reclaiming

of

the

oil dependson economic

and

local fact ors which

are

not considered

in

this document.

If

"

Reclaiming

"

is

considered

o

be

desirable,

ecommendations

may

be

found in

a

suitable

document

(see

ootnote,

page

15).

Handling

To

ensuresatislactoryservice, he utmost care

n handling the

oil before

filling into the equip.,

ment

is

essential.

Drums

used

or transport

and

storage

should be

kept

under

cover. In

practice,

owing to contamination n the containers,difficulty may be experiencedn maintaining the purity

of

the

oil when it

is transferred rom

one

vessel o

another,

and

once

a vesselor drum

has

been

filled with moist

oi l , i t

is

difficult

to

clean. Oil-handling equipment

pipework,

pumps)

should

be

kept

clean and

free from moisture. Before

use,

his

equipment should be

carefully

inspected

to

ensure

hat i t is free rom

dirt and water. and

flushed

with clean

oil.

When oil

is

stored n drums, these

should be

placed

n

such

a

posit ion

that

there is

a

head

of oil on

the

bung or

plug

to

prevent

he entry

of

water

during storage.

However,

t is recogmzed

that

storageof

oil in

drums s not alwayssatisfactory, nd

transfer

of such oil

to

electr ical quip-

ment through a

suitable

reatment

plant

is recommended.This

also applies

o

oil

in

drums

which

have

been

bent

or

otherwise

damased n transit or storase.

B2.

7/23/2019 SPLN 49-1B_1982.pdf


and

solids

rom

oil include

several ypes

The

best choice

of temperature

or

purification

depends

on circumstances. f

vacuum

treat-

rnent

is

employed to remove

water, temperatures

up to

80

oC

are advantageous ; f

not,

it is

advisable

to limit

the

temperature

to

60

oC

to

prevent

oxidation.

If

it is

desirable o reduce

precipitable

sludge

or

free

water without

vacuum treatment),

cold treatment may

be appropriate.

B3.2

Reconditioning

rocesses

83.2.1 Filters

Filter devicesare generallybased upon the principle

of

forcing

oil

under

pressure

hrough

absorbing material

such

as

paper.

Filters

of this type

are capable of removing

contaminants

n

suspension,

but they

cannot remove

them

effectively when

they

are dissolved

or

in

colloidal

form. These

devices

will

not

remove

air

and in

fact

tend to

aerate

he

oil.

The water-removing

ability

of the filter

is

dependant

upon

the

dryness

of the filter media.

When filtering

oi l

containing

water,

the filter

medium rapidly

comes nto

equilibrium

with the

water content

of

the

oil.

A continuous

ndication

of

the

water content

of the

outgoing

oil

is

very

helpful o fol low

the

efficiency

of the

process.

83.2.2

Centrifuges

83 .

8 3 . l

83.2.3

- 2 7 -

Reconditioning

*

G

eneral consideratiorts

The

physical

means

hat

are used or removing

water

of filter, centrifugeand vacuumdehydrator.

Another means or separatingcontaminants n suspension s the continuous centrifuge. n

general,

he

centrifuge

can handle

a

much greater

concentration

of contamination than

can

the

conventional

ilter

but cannot

remove

some of

the

contaminants

as completely

as

a

filter.

Conse-

quently,

the

centrifuge

s

generally

ound

in

use

for

rough

bulk

cleaning where

large

amounts

of

contaminated

il are to

be

handled.

Frequently,

he

output

of the

centrifuge s

put

through

a filter for

the final

clean

up .

Vacuum

dehydrators

The

vacuum

dehydrator

s

an efficientmeans

of

reducing

he

gas

and

water content

of an

insulating

oil

to

a very low

value. There

are two

types

of vacuum

dehydrator,

both of them

functioning

at elevated

emperature

or

a short time. In

one

method,

he treatment s accomplished

by

spraying

the

oil into

a vacuum

chamber; in

another, the

oil is

allowed to flow

over

a

series

of

baffies

nside

a vacuum

chamber

thus formins

thin

fllms.

If the

oil contains

solid

matter,

t is

advisable

o pass

t

through

processing

nder

vacuum.

The

operation

of vacuum

dehydrators s

continuous.

n

addition

dehydrators

will

degas he

oil and remove the

more

volatile

acids.

some kind

of a

filter

befbre

to

removing

water, vacuum

*

See reference

n footnote,

page

15 .

7/23/2019 SPLN 49-1B_1982.pdf


83.3

8 3 . 3 . 1

- 2 9 - -

Application

o electricalequipment

Direct

purification

The

oil

is removed

hrough

a

purilying plant

into

suitable

containers

nd,

when

the

electrical

equipment s to be refilled,passed hrough the purifier again nto the equipment.This method

should

be used

or

switchgear. t

is

suitable,

oo, for the

smaller

ransformer,but care

s

needed

to

ensure

hat the

core and windingsare

thoroughly cleaned.The oil-containing

housing

of

th e

equipmentshould also

be

well cleaned, y

meansof

oil originating

rom the

purifier.

The direct

purification

method requires

auxiliary

oil containers, nd

drums are sclrnetimessed.

83.3.2 Purificalion

by

circulation

The oil

is

circulated

hrough the

purifier,

being

taken

frorn the

bottom of

the

tank

of

th e

electr ical

equipment

and

redelivered o

the top.

The

return

delivery should be

made

smoothly

and horizontally at or near the surlace evel o avoid, as ar as possible,mixing cleanedoil with

oil which has

not

yet passed

hrough

the

purifier.

The circulation

method

s

particularly

useful

for removing

suspendednternalcontaminat ion

n

equipment, ut

al l adher ingcontaminat ion

will

not

necessarily

e

rernoved.

Experience

as shown that i t is

generallynecessary

o pass he total

volume

of

oil

thror.rgh

he

purif ier

not

less

han three imes,

and equipment

of appropriate

capacity

should be chosenwitl-r

th is n mind.

The inal

amount

passed

i l l depend n

the

degree f

contaminat iou,

nd

he

process

must

be continued

unti l a

sarnple

aken from the

bottom of

the

electr icalequipment,after

the

oil

has

been

allowed

o

sett le

or

a

few hours,

passes

he

electr icstrength

est.

The circulationshould

preferably

be

performed

with

the

electr ical

quipmentdead,and

this

is

essential hen using

a

purifier

which aerates

he

oil.

In

an emergency,

transformermay

be

left

alive while circulation s proceedingprovided that there is a closed systemof piping so that

aeration

of oil

is

avoided, but

this is not recommendedon transformers or vol tages

above

I I kV. Aeration

occurs

mostly with centrifugal

separators,

ther

than those

operating

under

vacuum,

and should

aerat ion

have occurred,

he

oi l shouldbe al lowed

o

stand

or some ime

before

he

equipment s macl e ive,

according

o

the manufacturer's ecommendation.

84.

Replacement

The dirty oil is replacedwith cleanoil. This method s usefulwhen dealingwith smallquantities

of oil in the smaller

circuit-breakers nd

isolating-switch

hambers.

A

small extra

quantity

of

clean

oil

is

needed

o rinse he interior

of

the tank

and

the

immersed

parts.

It

is

essential

ha t

the

tank

and

the

surfaces

f

conductorsand

insulators

be

kept free from fibres,

and

from moisture

from

the

hands

of

the

working

personnel;

uch

moisture

can easily

provide

suff icient

ontami-

nation

to lower

the

electric

strensth

of

the new

oil below

standard.

There

should be

as

ittle

aerationas

possible

uring

the f i l l ing

of

tanks

and, as

far

as

possible,

the

end of

the

delivery

pipe

shouldbe

held

below

he

surface f

the

oil

in

order

o

avoid

splashing;

alternatively , he tanks

should

be

filled from the

bottom. There

should be a standing

period

of

not less

han

one hour to

al low de-aerat ion efore ommissiorr ing

he

equipment.

7/23/2019 SPLN 49-1B_1982.pdf


3 l -

B5.

Precautionsn

the handlingand disposal f

mineral nsulatingoils

The

oils

with which

the

present

document

is

concerned are

mineral hydrocarbon

(pet-

roleum)

oils.

Whilst no

special isk s are

involved

in

the handling

and use of

mineral insulating

oils

(whether

inhibited or not), attention s drawn to the need or personalhygiene washingof skin and clothing

which

has

come

into contact

with oil) by

personnel

dealing

with

these

products.

When

used oil

has

o

be disposedof, certain

precautions

are

necessary

o

avoid

risk

of environ-

mental

pollution.

In most

countries,official advice

s

available on

these opics

and

legal

requirements

must

be

applied.

If the

precautions

and

regulations

applicable

o handling

and disposalof

industrial

and

other

lubricants

e.g.

utomobile rankcase rainings) re applied

o mineral nsulating

oils,

no problems

should arise.

7/23/2019 SPLN 49-1B_1982.pdf


E

d

o

.9'

.ir;

' P - . F

q U ,

o ( t

.O

C)

E E .

100 0

0 . 5

0.2

- 3 2 -

Tem p6ra tu re

e l ' hu i le ,

C

O i l

t e m p e r a t u r e ,

C

Etat de

I'huile isolanted6termin6

par

la r6sistance

n courant continu.

Condit ionof

insulat ine

i l

as

determined v d.c.

resistance.

120

Acceptable

Mauvais

Bad

Frc. l .

-

Documents

SPLN 49-1B_1982.pdf