EN 60695-1-40:2014
(Main)Fire hazard testing - Part 1-40: Guidance for assessing the fire hazard of electrotechnical products - Insulating liquids
Fire hazard testing - Part 1-40: Guidance for assessing the fire hazard of electrotechnical products - Insulating liquids
Provides guidance on the minimization of fire hazard arising from the use of electrical insulating liquids to a) electrotechnical equipment and systems, b) people, building structures and their contents. As insulating liquids are always part of an insulating system, the fire hazard of the complete system must also be assessed. Has the status of a basic safety publication in accordance with IEC Guide 104.
Prüfungen zur Beurteilung der Brandgefahr - Teil 1-40: Anleitung zur Beurteilung der Brandgefahr von elektrotechnischen Erzeugnissen - Isolierflüssigkeit
Essais relatifs aux risques du feu - Partie 1-40: Guide pour l'évaluation des risques du feu des produits électrotechniques - Liquides isolants
Fournit un guide pour la minimisation du risque de feu dans le cadre de l'utilisation de liquides isolants électriques a) pour les équipements et systèmes électrotechniques, b) pour les personnes, les structures des bâtiments et leur contenu. Comme les liquides isolants font toujours partie d'un système d'isolation, il faut également évaluer le risque de feu du système complet. A le statut d'une publication fondamentale de sécurité conformément au Guide 104 de la CEI.
Preskušanje požarne ogroženosti - 1-40. del: Navodilo za ocenjevanje požarne ogroženosti elektrotehničnih izdelkov - Izolacijske tekočine (IEC 60695-1-40:2013)
Standard EN-IEC 60695-1-40 nudi navodila za zmanjšanje požarne ogroženosti, ki izvira iz uporabe izolacijskih tekočin za električno izolacijo za: a) elektrotehnično opremo in sisteme, b) ljudi, stavbe in njihovo vsebino. Ta osnovna varnostna publikacija je namenjena tehničnim odborom za pripravo standardov v skladu z načeli vodil IEC Guide 104 in ISO/IEC Guide 51. Ni namenjena proizvajalcem ali certifikacijskim organom. Ena od odgovornosti tehničnih odborov je, da med pripravo publikacij uporabljajo osnovne varnostne publikacije, kadar je to primerno.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Essais relatifs aux risques du feu - Partie 1-40: Guide pour l'évaluation des risques du feu des produits électrotechniques - Liquides isolantsFire hazard testing - Part 1-40: Guidance for assessing the fire hazard of electrotechnical products - Insulating liquids29.040.01Izolacijski fluidi na splošnoInsulating fluids in general13.220.40Sposobnost vžiga in obnašanje materialov in proizvodov pri gorenjuIgnitability and burning behaviour of materials and productsICS:Ta slovenski standard je istoveten z:EN 60695-1-40:2014SIST EN 60695-1-40:2014en01-junij-2014SIST EN 60695-1-40:2014SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 60695-1-40 NORME EUROPÉENNE
EUROPÄISCHE NORM April 2014
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2014 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60695-1-40:2014 E
ICS 13.220.40; 29.020
English version
Fire hazard testing -
Part 1-40: Guidance for assessing the fire hazard of electrotechnical products -
Insulating liquids (IEC 60695-1-40:2013)
Essais relatifs aux risques du feu -
Partie 1-40: Guide pour l'évaluation des risques du feu des produits électrotechniques -
Liquides isolants (CEI 60695-1-40:2013)
Prüfungen zur Beurteilung der Brandgefahr -
Teil 1-40: Anleitung zur Beurteilung der Brandgefahr von elektrotechnischen Erzeugnissen -
Isolierflüssigkeit (IEC 60695-1-40:2013)
This European Standard was approved by CENELEC on 2013-12-24. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Foreword The text of document 89/1191/FDIS, future edition 1 of IEC 60695-1-40, prepared by IEC/TC 89 "Fire hazard testing" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 60695-1-40:2014. The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2014-10-25 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2016-12-24
This European Standard is to be used in conjunction with EN 60695-1-10. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 60695-1-40:2013 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: ISO 2719:2002 NOTE
Harmonised as EN ISO 2719:2002 (not modified). IEC 61039 NOTE
Harmonised as.EN 61039. IEC 62271-202 NOTE
Harmonised as.EN 62271-202. IEC 60708:2005 NOTE
Harmonised as.EN 60708:2005 (not modified). IEC 60794-1-1:2011 NOTE
Harmonised as.EN 60794-1-1:2011 (not modified). IEC 60836:2005 NOTE
Harmonised as.EN 60836:2005 (not modified). IEC 61099:2010 NOTE
Harmonised as.EN 61099:2010 (not modified). IEC 61144:1992 NOTE
Harmonised as.EN 61144:1993 (not modified). IEC 61197:1993 NOTE
Harmonised as.EN 61197:1994 (not modified). IEC 62271-105:2012 NOTE
Harmonised as.EN 62271-105:2012 (not modified). SIST EN 60695-1-40:2014
- 3 - EN 60695-1-40:2014 Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050
International electrotechnical vocabulary
IEC 60296
Fluids for electrotechnical applications - Unused mineral insulating oils for transformers and switchgear EN 60296
IEC 60465
Specification for unused insulating mineral oils for cables with oil ducts EN 60465
IEC 60695-1-10
Fire hazard testing - Part 1-10: Guidance for assessing the fire hazard of electrotechnical products - General guidelines EN 60695-1-10
IEC 60695-1-11
Fire hazard testing - Part 1-11: Guidance for assessing the fire hazard of electrotechnical products - Fire hazard assessment EN 60695-1-11
IEC 60695-4 2012 Fire hazard testing - Part 4: Terminology concerning fire tests for electrotechnical products EN 60695-4 2012
IEC/TS 60695-5-2
Fire hazard testing - Part 5-2: Corrosion damage effects of fire effluent - Summary and relevance of test methods
IEC 60695-6-2
Fire hazard testing - Part 6-2: Smoke obscuration - Summary and relevance of test methods EN 60695-6-2
IEC 60695-7-2
Fire hazard testing - Part 7-2: Toxicity of fire effluent - Summary and relevance of test methods EN 60695-7-2
IEC 60695-8-2
Fire hazard testing - Part 8-2: Heat release - Summary and relevance of test methods EN 60695-8-2
IEC/TS 60695-8-3
Fire hazard testing - Part 8-3: Heat release - Heat release of insulating liquids used in electrotechnical products
IEC 60944
Guide for maintenance of silicone transformer liquids
IEC 61039
Classification of insulating liquids EN 61039
IEC 61203
Synthetic organic esters for electrical purposes - Guide for maintenance of transformer esters in equipment EN 61203
ISO 1716
Reaction to fire tests for building products - Determination of the heat of combustion EN ISO 1716
ISO 2592
Determination of flash and fire points - Cleveland open cup method EN ISO 2592
ISO 13943 2008 Fire safety - Vocabulary EN ISO 13943 2010
IEC 60695-1-40 Edition 1.0 2013-11 INTERNATIONAL STANDARD NORME INTERNATIONALE Fire hazard testing –
Part 1-40: Guidance for assessing the fire hazard of electrotechnical products – Insulating liquids
Essais relatifs aux risques du feu –
Partie 1-40: Guide pour l’évaluation des risques du feu des produits électrotechniques – Liquides isolants INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE V ICS 13.220.40; 29.020 PRICE CODE CODE PRIX ISBN 978-2-8322-1170-0
BASIC SAFETY PUBLICATION PUBLICATION FONDAMENTALE DE SÉCURITÉ
– 2 – 60695-1-40 © IEC:2013 CONTENTS
FOREWORD . 4 INTRODUCTION . 6 1 Scope . 7 2 Normative references . 7 3 Terms and definitions . 8 4 Classification of insulating liquids . 13 5 Types of electrotechnical equipment containing insulating liquids . 13 6 Fire parameters . 14 6.1 General . 14 6.2 Ignition . 14 6.2.1 General . 14 6.2.2 Combustion . 14 6.2.3 Potential fire growth . 14 6.2.4 Fire effluent . 14 7 Fire scenarios . 14 7.1 General . 14 7.2 Origin fire scenarios . 14 7.2.1 General . 14 7.2.2 Major causes of fire . 15 7.2.3 Minor causes of fire . 16 7.2.4 Pool fires . 16 7.2.5 Burning spray . 16 7.2.6 Ignition on hot surface . 16 7.3 Victim fire scenarios . 16 8 Protective measures against fire . 17 9 Considerations for the selection of test methods . 17 9.1 General . 17 9.2 Type tests . 18 9.3 Sampling tests . 18 9.4 Arc resistance tests . 18 9.5 Relevance of test results to fire scenario . 18 Annex A (informative)
History of insulating liquids . 19 Annex B (informative)
Preventive and protective measures against fire . 20 B.1 General . 20 B.2 Physical protective measures . 20 B.3 Chemical protective measures . 20 B.4 Electrical protective measures . 20 B.5 Sensing devices . 20 B.6 Maintenance and inspection . 20 Annex C (informative)
Transformers. 22 C.1 General . 22 C.2 Transformer choice . 22 Annex D (informative)
Power capacitors . 24 SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 3 –Annex E (informative)
Cables. 25 E.1 Power cables . 25 E.2 Communication cables . 26 E.3 Cables with water blocking compounds . 26 E.4 Cable terminations . 26 Annex F (informative)
Bushings . 27 Annex G (informative)
Switchgear . 28 Bibliography . 29
Figure E.1 – Oil viscosity . 26
Table 1 – Classification of insulating liquids . 13
– 4 – 60695-1-40 © IEC:2013 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
FIRE HAZARD TESTING –
Part 1-40: Guidance for assessing the fire hazard
of electrotechnical products –
Insulating liquids
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60695-1-40 has been prepared by IEC technical committee 89: Fire hazard testing. This first edition of IEC 60695-1-40 cancels and replaces the first edition of IEC/TS 60695-1-40 published in 2002. It constitutes a technical revision and now has the status of an International Standard. The main changes with respect to the first edition of IEC/TS 60695-1-40 are the integration of editorial and technical changes throughout the text. SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 5 –The text of this standard is based on the following documents: FDIS Report on voting 89/1191/FDIS 89/1200/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all the parts in the 60695 series, under the general title Fire hazard testing, can be found on the IEC web site. This international standard is to be used in conjunction with IEC 60695-1-10. IEC 60695-1 consists of the following parts: – Part 1-10: Guidance for assessing the fire hazard of electrotechnical products – General guidelines – Part 1-11: Guidance for assessing the fire hazard of electrotechnical products – Fire hazard assessment – Part 1-12: Guidance for assessing the fire hazard of electrotechnical products – Fire safety engineering – Part 1-20: Guidance for assessing the fire hazard of electrotechnical products – Ignitability – General guidance – Part 1-21: Guidance for assessing the fire hazard of electrotechnical products – Ignitability – Summary and relevance of test methods – Part 1-30: Guidance for assessing the fire hazard of electrotechnical products – Preselection testing process
General guidelines – Part 1-40: Guidance for assessing the fire hazard of electrotechnical products – Insulating liquids The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
– 6 – 60695-1-40 © IEC:2013 INTRODUCTION In the design of any electrotechnical product the risk of fire and the potential hazards associated with fire need to be considered. In this respect the objective of component, circuit and product design as well as the choice of materials is to reduce to acceptable levels the potential risks of fire even in the event of foreseeable abnormal use, malfunction or failure. For more than 100 years, insulating liquids based on mineral oil have been used for the insulating and cooling of electrical transformers and some other types of electrotechnical equipment. During the last 70 years, synthetic insulating liquids have been developed and used in specific electrotechnical applications for which their properties are particularly suitable. However, for technical and economic reasons, highly refined mineral oil continues to be the most widely used insulating liquid for use in transformers, the major end use application. Their safe installation is covered by local, national and international regulations. The fire safety record of electrotechnical equipment containing insulating liquids is good, for both mineral oil and synthetic liquids. In recent years improvements in design and protective measures against fire have reduced the fire hazard for electrotechnical equipment containing mineral oil. However, as for all forms of electrotechnical equipment, the objective should be to reduce the likelihood of fire even in the event of foreseeable abnormal use. The practical aim is to prevent ignition, but if ignition occurs, to control the fire, preferably within the enclosure of the electrotechnical equipment.
60695-1-40 © IEC:2013 – 7 –FIRE HAZARD TESTING –
Part 1-40: Guidance for assessing the fire hazard
of electrotechnical products –
Insulating liquids
1 Scope This international standard provides guidance on the minimization of fire hazard arising from the use of electrical insulating liquids, with respect to: a) electrotechnical equipment and systems, b) people, building structures and their contents. This basic safety publication is intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 [1]1 and ISO/IEC Guide 51 [2]. It is not intended for use by manufacturers or certification bodies. One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050, International electrotechnical vocabulary IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for transformers and switchgear IEC 60465, Specification for unused insulating mineral oils for cables with oil ducts IEC 60695-1-10, Fire hazard testing
Part 1-10: Guidance for assessing the fire hazard of electrotechnical products
General guidelines IEC 60695-1-11, Fire hazard testing
Part 1-11: Guidance for assessing the fire hazard of electrotechnical products
Fire hazard assessment IEC 60695-4:2012, Fire hazard testing – Part 4: Terminology concerning fire tests for electrotechnical products IEC 60695-6-2, Fire hazard testing – Part 6-2: Smoke obscuration – Summary and relevance of test methods IEC 60695-7-2, Fire hazard testing – Part 7-2: Toxicity of fire effluent – Summary and relevance of test methods ______________ 1
Numbers in square brackets refer to the Bibliography. SIST EN 60695-1-40:2014
– 8 – 60695-1-40 © IEC:2013 IEC 60695-8-2, Fire hazard testing – Part 8-2: Heat release – Summary and relevance of test methods IEC 60944, Guide for the maintenance of silicone transformer liquids IEC 61039, Classification of insulating liquids IEC 61203, Synthetic organic esters for electrical purposes – Guide for maintenance of transformer esters in equipment IEC/TS 60695-5-2, Fire hazard testing – Part 5-2: Corrosion damage effects of fire effluent – Summary and relevance of test methods IEC/TS 60695-8-3, Fire hazard testing – Part 8-3: Heat release – Heat release of insulating liquids used in electrotechnical products ISO 1716, Reaction to fire tests for products – Determination of the gross heat of combustion (calorific value) ISO 2592, Determination of flash and fire points
Cleveland open cup method ISO 13943:2008, Fire safety
Vocabulary 3 Terms and definitions For the purposes of this document, terms and definitions given in ISO 13943:2008 and IEC 60695-4:2012, some of which are reproduced below for the user’s convenience, as well as the following additional definitions, apply. 3.1
arc electrical breakdown of a gas which produces a sustained plasma discharge, resulting from an electric current flowing through a normally nonconductive medium such as air 3.2
bund outer wall or tank designed to retain the contents of an inner container in the event of leakage or spillage Note 1 to entry: A bund should be designed to capture well in excess of the volume of liquids held within the bund area. 3.3
bushing insulating liner in an opening through which a conductor passes 3.4
combustion exothermic reaction of a substance with an oxidizing agent Note 1 to entry: Combustion generally emits fire effluent accompanied by flames and/or glowing. [SOURCE: ISO 13943:2008, 4.46] 3.5
corrosion damage physical and/or chemical damage or impaired function caused by chemical action SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 9 –[SOURCE: ISO 13943:2008, 4.56] 3.6
enclosure electrotechnical external casing protecting the electrical and mechanical parts of apparatus Note 1 to entry: The term excludes cables. [SOURCE: IEC 60695-4:2012, 3.2.6] 3.7
fire generalprocess of combustion characterized by the emission of heat and fire effluent and usually accompanied by smoke, flame, glowing or a combination thereof Note 1 to entry: In the English language the term “fire” is used to designate three concepts, two of which, fire and fire, relate to specific types of self-supporting combustion with different meanings and two of them are designated using two different terms in both French and German. [SOURCE: ISO 13943:2008, 4.96] 3.8
fire effluent totality of gases and aerosols, including suspended particles, created by combustion or pyrolysis in a fire [SOURCE: ISO 13943:2008, 4.105] 3.9
fire growth stage of fire development during which the heat release rate and the temperature of the fire are increasing [SOURCE: ISO 13943:2008, 4.111] 3.10
fire hazard physical object or condition with a potential for an undesirable consequence from fire [SOURCE: ISO 13943:2008, definition 4.112] 3.11
fire Ioad quantity of heat which can be released by the complete combustion of all the combustible materials in a volume, including the facings of all bounding surfaces Note 1 to entry: Fire load may be based on effective heat of combustion, gross heat of combustion, or net heat of combustion as required by the specifier. Note 2 to entry: The word “load” can be used to denote force or power or energy. In this context, it is being used to denote energy. Note 3 to entry: The typical units are kilojoules (kJ) or megajoules (MJ). [SOURCE: ISO 13943:2008, 4.114] 3.12
fire point minimum temperature at which a material ignites and continues to burn for a specified time after a standardized small flame has been applied to its surface under specified conditions SIST EN 60695-1-40:2014
– 10 – 60695-1-40 © IEC:2013 Note 1 to entry: In some countries, the term “fire point” has an additional meaning: a location where fire-fighting equipment is sited, which may also comprise a fire-alarm call point and fire instruction notices. Note 2 to entry: The typical units are degrees Celsius (C). [SOURCE: ISO 13943:2008, 4.119] 3.13
fire risk probability of a fire combined with a quantified measure of its consequence Note 1 to entry: It is often calculated as the product of probability and consequence. [SOURCE: ISO 13943:2008, 4.124] 3.14
fire scenario qualitative description of the course of a fire with respect to time, identifying key events that characterise the studied fire and differentiate it from other possible fires Note 1 to entry: It typically defines the ignition and fire growth processes, the fully developed fire stage, the fire decay stage, and the environment and systems that impact on the course of the fire. [SOURCE: ISO 13943:2008, 4.129] 3.15
flame, noun zone in which there is rapid, self-sustaining, sub-sonic propagation of combustion in a gaseous medium, usually with emission of light [SOURCE: ISO 13943:2008, 4.133
modified by addition of "zone in which there is"] 3.16
flammability ability of a material or product to burn with a flame under specified conditions [SOURCE: ISO 13943:2008, 4.151] 3.17
flash point minimum temperature to which it is necessary to heat a material or a product for the vapours emitted to ignite momentarily in the presence of flame under specified conditions Note 1 to entry: The typical units are degrees Celsius (C). [SOURCE: ISO 13943:2008, 4.154] 3.18
gross heat of combustion heat of combustion of a substance when the combustion is complete and any produced water is entirely condensed under specified conditions Note 1 to entry: The typical units are kilojoules per gram (kJg-1). [SOURCE: ISO 13943:2008, 4.170] 3.19
heat of combustion thermal energy produced by combustion of unit mass of a given substance SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 11 –Note 1 to entry: The typical units are kilojoules per gram (kJg-1). [SOURCE: ISO 13943:2008, 4.174] 3.20
heat of gasification thermal energy required to change a unit mass of material from the condensed phase to the vapour phase at a given temperature Note 1 to entry: The typical units are kilojoules per gram (kJg-1). [SOURCE: ISO 13943:2008, 4.175] 3.21
heat release thermal energy produced by combustion Note 1 to entry: The typical units are joules (J). [SOURCE: ISO 13943:2008, 4.176] 3.22
heat release rate burning rate (deprecated) rate of burning (deprecated) rate of thermal energy production generated by combustion Note 1 to entry: The typical units are watts (W). [SOURCE: ISO 13943:2008, 4.177] 3.23
high voltage HV voltage greater than 1 kV (a.c.) or greater than 1,5 kV (d.c.) 3.24
ignitability ease of ignition measure of the ease with which a test specimen can be ignited, under specified conditions [SOURCE: ISO 13943:2008, 4.182] 3.25
ignition sustained ignition (deprecated) general initiation of combustion [SOURCE: ISO 13943:2008, 4.187] 3.26
mineral oil liquid conforming to IEC 60296 or IEC 60465 3.27
net heat of combustion heat of combustion when any water produced is considered to be in the gaseous state SIST EN 60695-1-40:2014
– 12 – 60695-1-40 © IEC:2013 Note 1 to entry: The net heat of combustion is always smaller than the gross heat of combustion because the heat released by the condensation of water vapour is not included. Note 2 to entry: The typical units are kilojoules per gram (kJg-1). [SOURCE: ISO 13943:2008, 4.237] 3.28
opacity of smoke ratio of incident light intensity to transmitted light intensity through smoke, under specified conditions Note 1 to entry: Opacity of smoke is the reciprocal of transmittance. Note 2 to entry: The opacity of smoke is dimensionless. [SOURCE: ISO 13943:2008, 4.243] 3.29
origin fire scenario fire scenario involving electrotechnical equipment where the electrotechnical equipment is the source of ignition 3.30
PCB polychlorinated biphenyl Note 1 to entry: PCB mixtures were developed as insulating liquids in the 1930s. They are known by various trade names, e.g. Aroclor, Askarel, Clophen, Inerteen and Pyranol 2. 3.31
pool fire fire characterized by diffusion flames formed above a horizontal body of liquid fuel where buoyancy is the controlling mechanism for transport of fire effluent from the fire and transport of air to the fire 3.32
routine test test on a number of items taken at random from a batch 3.33
sampling test conformity test made on each individual item during or after manufacture [SOURCE: IEC 60050-151:2001, 151-16-17, modified – original term was “routine test”] 3.34
tapchanger device fitted to power transformers for regulation of the output voltage to required levels 3.35
toxic hazard potential for harm resulting from exposure to toxic combustion products [SOURCE: ISO 13943:2008, 4.337] ______________ 2
Aroclor, Askarel, Clophen, Inerteen and Pyranol are examples of suitable products available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement by IEC of these products. SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 13 –3.36
type test conformity test made on one or more items representative of the production [SOURCE: IEC 60050-581:2008, 581-21-08] 3.37
victim fire scenario fire scenario involving electrotechnical equipment where the electrotechnical equipment is the victim of a fire of external origin 4 Classification of insulating liquids Insulating liquids have been classified in IEC 61039 according to fire point and net heat of combustion, as shown in Table 1. Table 1 – Classification of insulating liquids Fire point Net heat of combustion Class O 300 C Class 1 42 MJ/kg Class K 300 C Class 2 42 MJ/kg 32 MJ/kg Class L No measurable fire point Class 3 32 MJ/kg EXAMPLE Mineral transformer oil (IEC 60296) has a classification of O1.
NOTE 1 Fire point is measured using the Cleveland open cup method, ISO 2592, and is used as the primary method of classification. NOTE 2 The determination of the flash point is sometimes used as a secondary method of classification. IEC TC10 usually adopts ISO 2719:2002 [3] in order to measure the flash point using the Pensky-Martens methodology (closed cup).
If the value of the flash point determined by this method is
250 °C, then the product is classified with the letter “O”; if the flash point is
250 °C, then the product is classified with the letter “K”, and, if there is no detectable flash point, the product is classified with the letter “L”. 5 Types of electrotechnical equipment containing insulating liquids Insulating liquids are used in some designs of: – transformers and reactors, – capacitors, – cables, – bushings, – switchgear, and – miscellaneous power electronics (and in some other electrotechnical applications in which the liquid serves partly as an insulant, but primarily as a coolant) In many cases, alternative designs use solid or gaseous insulation materials as an alternative to liquids. This international standard does not discuss the relative advantages and disadvantages of these alternatives. NOTE As insulating liquids are always part of an insulating system, the fire hazard assessment of the complete system could also be of interest. SIST EN 60695-1-40:2014
– 14 – 60695-1-40 © IEC:2013 6 Fire parameters 6.1 General The main parameters which relate to the ignition and combustion of insulating liquids are described in 6.2. 6.2 Ignition 6.2.1 General Ignitability can be measured by fire point as described in ISO 2592. 6.2.2 Combustion Combustion characteristics are be considered in terms of the contribution to the fire load, the potential fire growth, and the fire hazards caused by fire effluent. NOTE A fire may not cause the insulating liquid to burn but may cause leakage of the insulating liquid. In this case, the hazards caused by leakage should also be considered. 6.2.3 Potential fire growth Important parameters relating to the potential fire growth are net heat of combustion, heat release rate and heat of gasification. 6.2.4 Fire effluent The important hazardous effects of fire effluent are opacity of smoke, corrosion damage and toxic hazard. 7 Fire scenarios 7.1 General Fire scenarios for electrotechnical equipment containing insulating liquids are described below. These fire scenarios are particularly relevant for transformers, the major end use application for insulating liquids, and in some cases for other types of electrotechnical equipment. The fire hazard shall be assessed with reference to IEC 60695-1-10 and IEC 60695-1-11. For electrotechnical equipment containing insulating liquids, the two types of scenario that are considered are: a) when the electrotechnical equipment is the source of ignition, known as an “origin fire scenario”, and b) when the electrotechnical equipment is the victim of a fire of external origin, known as a “victim fire scenario”. In the origin fire scenario, fire is initiated by failure within the electrotechnical equipment. In the victim fire scenario, the insulating liquid contributes to the fire load for a fire of external origin. 7.2 Origin fire scenarios 7.2.1 General Consideration shall be given to SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 15 –a) whether the insulating liquid can be heated to its fire point under equipment overload conditions. This could result in fire initiation if exposed to an external source of ignition; b) whether fire can be initiated by an uncontrolled high-energy internal arc. Either of these situations may create internal pressure sufficient to rupture the insulating liquid container in the electrotechnical equipment. The liquid is then ejected, normally as a spray, which may be ignited. The spray burns intensely for a short period but then forms a pool, which may or may not be burning at the base of the electrotechnical equipment. Experience with Class O1 insulating liquids has shown that burning of a resultant pool fire causes most damage but no pool fires have been reported for Class K liquids. Tests on Class K insulating liquids (known as less-flammable insulating liquids) have shown that even if spray ignites, the resulting pool of liquid rapidly ceases to burn. This is largely due to its high fire point. However, mineral oils (Class O1) are much more likely to continue to burn as a pool fire. Therefore, much of the information relating to fire damage applies to Class O1 liquids. PCB mixtures (see 3.30 and Annex A) exhibit similar behaviour to Class K insulating liquids. The spray and dissolved gases can ignite, even though PCB mixtures are rated as Class L. The resulting pool will not continue to burn. For many types of electrotechnical equipment, Class O1 insulating liquids are almost always used for technical and/or economic reasons. Protection against fire can then be provided by appropriate design and safe location of the electrotechnical equipment, including physical and electrical control devices (see Annex B). Class K insulating liquids require less stringent protective measures than Class O insulating liquids (see Annexes A and C). The major use of insulating liquids is in transformers. The following lists of major and minor fire scenarios apply to transformers and in some cases to other types of electrotechnical equipment containing insulating liquids. Provisions shall be made for protection of people against fire effluent or other effluent from equipment containing PCB mixtures or mineral oil contaminated by PCBs. Such equipment shall be identified and dealt with in accordance with local regulations which may result in decommissioning. This is important because PCBs present a toxic hazard if decomposed thermally with or without combustion of the carrier liquid [4]. Although failures leading to a fire in electrotechnical equipment containing insulating liquids are rare, it is evident that any equipment transmitting a high level of electrical energy and containing significant quantities of flammable solid and/or liquid insulating materials presents a potential fire hazard. With good protective measures, damage caused is usually small and confined to within the container, with possible ejection of a small quantity of insulating liquid. 7.2.2 Major causes of fire The major causes of fire in origin fire scenarios are as follows: a) Container damage leading to a leakage of insulating liquid, possibly in the form of a liquid spray. b) An increase in internal container pressure due to thermal expansion under overload or to the production of gases from the decomposition of the insulating liquid. This can result in the release of liquid and vapours from a pressure relief valve. c) Undetected leakage leading to a lack of circulation, resulting in overheating and a change in liquid characteristics, eventually leading to breakdown due to arcing from exposed conductors. SIST EN 60695-1-40:2014
– 16 – 60695-1-40 © IEC:2013 d) A high energy arc, or arcs, between incoming HV terminations caused by high voltage transients, lightning or a switching surge. e) Low magnitude faults in the centre of HV windings, causing breakdown and decomposition of the insulating liquid into flammable gaseous components. f) Failure of protection to clear a fault, resulting in severe overheating and winding failure. g) Tapchanger faults – failure may spread to the transformer. h) Bushing faults in an overheated connection resulting in a cracked insulator. This can result in the slow release of insulating liquid on to the overheated connection, which may cause a fire if not detected.
i) Cable box faults – cable boxes may be either compound-filled or oil-filled. Failure of the insulation may cause a phase-to-phase arc and the resulting high pressure could cause the cable box to burst.
j) Oil-filled cable faults.
7.2.3 Minor causes of fire The minor causes of fire in origin fire scenarios are as follows: a) An overheated connection resulting in a cracked insulator. b) A slow release of insulating liquid on to an overheated connection. Depending on the combustion characteristics of the liquid, this may cause a fire if not detected. 7.2.4 Pool fires Experience with mineral oil-filled transformers has shown that, if the transformer tank is ruptured by a catastrophic failure caused by a high energy internal arc, the insulating liquid can be ejected as a spray. This spray burns intensely for a short time and can itself cause damage, but, in most recorded accidents, a considerable contribution to total fire damage was caused by the high heat release rate from the resulting burning pool of oil. For this reason, the possibility of a pool fire must be a matter for particular consideration. 7.2.5 Burning spray Spray may burn intensely for only a short period of time. Pressure is limited by comparison with e.g. hydraulic applications, because the container in most electrotechnical equipment has only a limited pressure withstand capability. 7.2.6 Ignition on hot surface A fault in a high current connection, external to the electrotechnical equipment, can result in a high local temperature, possibly exceeding 500 C. If insulating liquid leaks from the electrotechnical equipment and runs over such an overheated surface, it may ignite. This will be dependent on the temperature of the surface, the ignition temperature of the liquid, and the rate of flow. 7.3 Victim fire scenarios The electrotechnical equipment under consideration can be involved when a fire begins externally. This could include collapse of a building causing damage to the container and release of the insulating liquid into a pool which can ignite.
Another type of victim fire scenario is an interactive fire, which begins in adjacent associated electrotechnical equipment, such as connecting cables, capacitors or switchgear. For example, fire damage to connecting cables can result in a short-circuit. Consideration shall be given to the probability that the insulating liquid can be exposed to an external fire, whether the liquid is fully contained within the electrotechnical equipment or is released after physical damage to the equipment. Important parameters are the ignitability of SIST EN 60695-1-40:2014
60695-1-40 © IEC:2013 – 17 –the insulating liquid and, if ignition occurs, the contribution to the fire hazard of heat release and fire effluent. In a victim fire scenario, Class K (less-flammable) insulating liquids can be heated to a higher temperature than Class O insulating liquids before they will ignite in contact with an external flame and continue to burn. 8 Protective measures against fire Protective measures against fire are as follows: a) the retention of the insulating liquid within the electrotechnical equipment, allowing for thermal expansion in service; b) provision to retain any liquid released, by means of a sump or bund; c) ensuring that there is a sufficient distance to the nearest building (for outdoor installations); d) the use of fire barriers or fire compartments; e) provision of a fire extinguisher or extinguishers actuated by excess temperature rise; f) provision of a circuit breaker
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