SIST EN 60507:2014

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Essais sous pollution artificielle des isolateurs haute tension en céramique et en verre destinés aux réseaux à courant alternatifArtificial pollution tests on high-voltage ceramic and glass insulators to be used on a.c. systems29.080.10IzolatorjiInsulatorsICS:Ta slovenski standard je istoveten z:EN 60507:2014SIST EN 60507:2014en01-oktober-2014SIST EN 60507:2014SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 60507 NORME EUROPÉENNE
EUROPÄISCHE NORM March 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 60507:2014 E
ICS 29.080.10 Supersedes EN 60507:1993
English version
Artificial pollution tests on high-voltage ceramic and glass insulators to be used on a.c. systems (IEC 60507:2013)
Essais sous pollution artificielle des isolateurs haute tension en céramique et en verre destinés aux réseaux à courant alternatif (CEI 60507:2013)
Fremdschichtprüfungen an Hochspannungs-Isolatoren aus Keramik und Glas zur Anwendung in Wechselspannungssystemen (IEC 60507:2013)
This European Standard was approved by CENELEC on 2014-01-17. 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.
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) 2014-10-17 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2017-01-17
This document supersedes EN 60507:1993.
EN 60507:1993: a) Corrections and the addition of explanatory material; b) The addition of Clause 4.4.2 on atmospheric correction; c) The change of the upper limit of conductivity of water to 0.1 S/m; and d) The extension to UHV voltages.
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 60507:2013 was approved by CENELEC as a European Standard without any modification. SIST EN 60507:2014

- 3 - EN 60507:2014 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 60060-1 - High-voltage test techniques -
Part 1: General definitions and test requirements EN 60060-1 -
IEC 60071-1 - Insulation co-ordination -
Part 1: Definitions, principles and rules EN 60071-1 -
IEC/TS 60815-1 - Selection and dimensioning of high-voltage insulators intended for use in polluted conditions -
Part 1: Definitions, information and general principles - -
IEC/TS 60815-2 - Selection and dimensioning of high-voltage insulators intended for use in polluted conditions -
Part 2: Ceramic and glass insulators for a.c. systems - -
IEC 60507 Edition 3.0 2013-12 INTERNATIONAL STANDARD NORME INTERNATIONALE Artificial pollution tests on high-voltage ceramic and glass insulators to be used on a.c. systems
Essais sous pollution artificielle des isolateurs haute tension en céramique et en verre destinés aux réseaux à courant alternatif
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE W ICS 29.080.10 PRICE CODE CODE PRIX ISBN 978-2-8322-1297-4
– 2 – 60507 © IEC:2013
CONTENTS
FOREWORD . 5 1 Scope . 7 2 Normative references . 7 3 Terms and definitions . 7 4 General test requirements . 10 4.1 General . 10 4.2 Test method . 10 4.3 Arrangement of insulator for test . 10
Test configuration . 10 4.3.1 Cleaning of insulator . 11 4.3.24.4 Requirements for the testing plant . 11
Test voltage . 11 4.4.1 Atmospheric corrections . 11 4.4.2 Minimum short-circuit current . 12 4.4.35 Salt fog method . 13 5.1 General information . 13 5.2 Salt solution . 13 5.3 Spraying system . 15 5.4 Conditions before starting the test. 18 5.5 Preconditioning process . 18 5.6 Withstand test . 19 5.7 Acceptance criterion for the withstand test . 19 6 Solid layer methods . 19 6.1 General information . 19 6.2 Main characteristics of inert materials . 20 6.3 Composition of the contaminating suspension . 20
General . 20 6.3.1 Kieselguhr composition . 20 6.3.2 Kaolin (or Tonoko) composition . 21 6.3.36.4 Application of the pollution layer . 22 6.5 Determination of the degree of pollution of the tested insulator . 23
General . 23 6.5.1 Layer conductivity (K) . 23 6.5.2 Salt deposit density (SDD) . 23 6.5.36.6 General requirements for the wetting of the pollution layer . 24 6.7 Test procedures . 24
General . 24 6.7.1 Procedure A – Wetting before and during energization . 24 6.7.2 Procedure B – Wetting after energization . 26 6.7.36.8 Withstand test and acceptance criterion (common to both Procedures A and B) . 27 Annex A (informative)
Supplementary information on the assessment of the requirement for the testing plant . 28 Annex B (informative)
Determination of the withstand characteristics of insulators . 29 B.1 General . 29 SIST EN 60507:2014

60507 © IEC:2013 – 3 – B.2 Determination of the maximum withstand salinity at a given test voltage . 29 B.3 Determination of the maximum withstand voltage, or of the 50 % withstand voltage, at a given reference layer conductivity, or at a given reference salt deposit density . 29 B.3.1 Maximum withstand voltage . 29 B.3.2 50 % withstand voltage . 30 B.4 Withstand values of reference suspension insulators . 30 Annex C (informative)
Measurement of layer conductivity for checking the uniformity of the layer . 32 Annex D (informative)
Additional recommendations concerning the solid layer method procedures. 34 D.1 General . 34 D.2 Contamination practice . 34 D.3 Drying of the pollution layer . 34 D.4 Check of the wetting action of the fog . 34 D.5 Checking fog uniformity for large or complex test objects . 35 D.6 Fog input in the test chamber . 35 D.7 Minimum duration of the withstand test . 35 D.8 Evaluation of the reference salt deposit density (SDD) . 36 Annex E (informative)
Supplementary information on artificial pollution tests on insulators for voltage systems of 800 kV and above (solid layer method procedure B) . 37 E.1 Introduction . 37 E.2 Test chamber . 37 E.3 Fog generator . 37 E.4 Wetting action and uniformity of fog density . 37 Bibliography . 38
Figure 1 – Minimum short-circuit current, Isc min, required for the testing plant as a function of the unified specific creepage distance (USCD) of the insulator under test . 13 Figure 2 – Value of factor b as a function of solution temperature . 15 Figure 3 – Typical construction of fog spray nozzle . 17 Figure 4 – Test layout for inclined insulators . 18 Figure 5 – Typical arrangement of steam-fog generator . 26 Figure C.1 – Arrangement of the probe electrodes
(all dimensions in mm) . 32 Figure C.2 – Circuit diagram of the meter . 33 Figure D.1 – Control of the wetting action of the steam fog: Layer conductance recording during the test on the chosen dummy insulator (standard type of Table B.1) . 36
Table 1 – Salt-fog method: correspondence between the value of salinity,
volume conductivity and density of the solution at a temperature of 20 °C . 14 Table 2 – Main characteristics of the inert materials used in solid layer suspensions . 20 Table 3 – Kieselguhr composition: approximate correspondence between
the reference degrees of pollution on the insulator and the volume conductivity
of the suspension at a temperature of 20 °C . 21 Table 4 – Kaolin (or Tonoko) composition: approximate correspondence
between the reference degrees of pollution on the insulator and the volume conductivity of the suspension at a temperature of 20 °C . 22 Table A.1 – Expected Ih max values related to different USCD values . 28 SIST EN 60507:2014

– 4 – 60507 © IEC:2013 Table B.1 – Ranges of values of withstand characteristics of reference suspension insulators in artificial pollution tests . 31
60507 © IEC:2013 – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ______________
ARTIFICIAL POLLUTION TESTS ON HIGH-VOLTAGE CERAMIC
AND GLASS INSULATORS TO BE USED ON A.C. SYSTEMS
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 60507 has been prepared by IEC technical committee 36: Insulators. This third edition cancels and replaces the second edition published in 1991. This third edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Corrections and the addition of explanatory material; b) The addition of Clause 4.3.2 on atmospheric correction; c) The change of the upper limit of conductivity of water to 0.1 S/m; and d) The extension to UHV voltages.
– 6 – 60507 © IEC:2013 The text of this standard is based on the following documents: FDIS Report on voting 36/337/FDIS 36/342/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.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.
60507 © IEC:2013 – 7 – ARTIFICIAL POLLUTION TESTS ON HIGH-VOLTAGE CERAMIC
AND GLASS INSULATORS TO BE USED ON A.C. SYSTEMS
1 Scope This International Standard is applicable for the determination of the power frequency withstand characteristics of ceramic and glass insulators to be used outdoors and exposed to polluted atmospheres, on a.c. systems with the highest voltage of the system greater than 1 000 V. These tests are not directly applicable to polymeric insulators, to greased insulators or to special types of insulators (insulators with semiconducting glaze or covered with any organic insulating material). The object of this International Standard is to prescribe procedures for artificial pollution tests applicable to insulators for overhead lines, substations and traction lines and to bushings It may also be applied to hollow insulators with suitable precautions to avoid internal flashover. In applying these procedures to apparatus incorporating hollow insulators, the relevant technical committees should consider their effect on any internal equipment and the special precautions which may be necessary. 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 60071-1, Insulation co-ordination – Part 1: Definitions, principles and rules IEC/TS 60815-1, Selection and dimensioning of high-voltage insulators intended for use in polluted conditions – Part 1: Definitions, information and general principles IEC/TS 60815-2, Selection and dimensioning of high-voltage insulators intended for use in polluted conditions – Part 2: Ceramic and glass insulators for a.c. systems IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements 3 Terms and definitions For the purpose of this standard, the following terms and definitions apply. 3.1
test voltage the r.m.s. value of the voltage with which the insulator is continuously energized throughout the test 3.2
short-circuit current (Isc) of the testing plant the r.m.s. value of the current delivered by the testing plant when the test object is short-circuited at the test voltage SIST EN 60507:2014

– 8 – 60507 © IEC:2013 3.3
unified specific creepage distance USCD the creepage distance of an insulator divided by the maximum operating voltage across the insulator (for a.c. systems usually Um/√3) Note 1 to entry: This is generally expressed in mm/kV. Note 2 to entry: This definition differs from that of Specific Creepage Distance where the phase-to-phase value of the highest voltage for the equipment is used. For phase-to-earth insulation, this definition will result in a value that is √3 times that given by the definition of Specific Creepage Distance in IEC/TS 60815 (1986). See Annex J of IEC 60815-1:2008 for details. 3.4
form factor of an insulator Ff dimensionless number that presents the length (l) of the partial creepage distance divided by the integrated width (p) Note 1 to entry: For insulators, the length is in the direction of the creepage distance and the width is the circumference of the insulator. Note 2 to entry: The form factor is calculated by the formula ()∫=L0lpdlFf where L
is the total creepage distance p(l)
= 2π.r(l) For graphical estimation of the form factor, the reciprocal value of the insulator circumference (p1) is plotted versus the partial creepage distance l counted from the end of the insulator up to the point reckoned. The form factor is given by the area under this curve. 3.5
salinity Sa concentration of the solution of salt in tap water, expressed by the amount of salt divided by the volume of solution Note 1 to entry: This is generally expressed in kg/m3. 3.6
pollution layer a conducting electrolytic layer on the insulator surface, composed of salt plus inert materials Note 1 to entry: The conductance of the pollution layer on the insulator is measured in accordance with 6.5.1. 3.7
layer conductivity (K) the conductance of the pollution layer multiplied by the form factor Note 1 to entry: This is generally expressed in µS. SIST EN 60507:2014

60507 © IEC:2013 – 9 – 3.8
salt deposit density SDD amount of sodium chloride in an artificial deposit on a given surface of the insulator (metal parts and assembling materials are not to be included in this surface) divided by the area of this surface Note 1 to entry: This is generally expressed in mg/cm2. 3.9
degree of pollution the value of the quantity (salinity, layer conductivity, salt deposit density) which characterizes the artificial pollution applied to the tested insulator 3.10
reference salinity the value of the salinity used to characterize a test 3.11
reference layer conductivity the value of the layer conductivity used to characterize a test Note 1 to entry: This is defined as the maximum value of the conductivity of the wetted layer of an insulator energized only for performing the conductance measurements. 3.12
reference salt deposit density the value of the salt deposit density used to characterize a test Note 1 to entry: This is defined as the average of the salt deposit density values measured on a few insulators (or on parts of them), which are chosen for this purpose from among the contaminated ones prior to their submission to any test. 3.13
specified withstand degree of pollution the reference degree of pollution at which an insulator shall withstand the specified test voltage in at least three tests out of four, under the conditions described in the relevant Clauses 5.6 or 6.8 3.14
maximum withstand degree of pollution the highest degree of pollution at which at least three withstand tests out of four can be obtained at the specified test voltage, under the conditions described in the relevant clauses 5.6 or 6.8. 3.15
specified withstand voltage the test voltage at which an insulator shall withstand the specified degree of pollution in at least three tests out of four, under the conditions described in the relevant 5.6 or 6.8 3.16
maximum withstand voltage the highest test voltage at which at least three withstand tests out of four can be obtained at the specified degree of pollution, under the conditions described in the relevant 5.6 or 6.8 3.17
non-soluble deposit density NSDD amount of non-soluble residue removed from a given surface of the insulator, divided by the area of this surface SIST EN 60507:2014

– 10 – 60507 © IEC:2013 Note 1 to entry: This is generally expressed in mg/cm2. 4 General test requirements 4.1 General Pollution tests can be carried out for two main objectives: • to obtain information about the pollution performance of insulators e.g. for comparison of different insulator types/profile • to check the performance in a configuration as close as possible to the in-service one. To reach the first objective, tests on relatively short insulator sets – if representative of the full set in terms of radial geometry and profile – may be sufficient. Results of such tests on insulators with an arcing length higher than 1 m can be linearly extrapolated up to and including the UHV range, at least for pollution ranging from medium to very heavy. Tests to reach the second objective may be agreed between the manufacturer and the user whenever optimisation of the design is necessary and/or whenever it is expected that the mounting condition or the inner active parts in apparatus can affect the performance. Such tests shall be made simulating the relevant service conditions as closely as possible. In particular tests in other positions from the vertical (inclined, horizontal) duplicating actual service conditions may be agreed between the supplier and the user. Tests at higher system voltages (800 kV and above) may present particular requirements as reported in Annex E. 4.2 Test method The two following categories of pollution test methods are recommended for standard tests: – the salt fog method (Clause 5) in which the insulator is subjected to a defined ambient pollution; – the solid layer method (Clause 6) in which a fairly uniform layer of a defined solid pollution is deposited on the insulator surface; NOTE 1 In these test methods the voltage is held constant for a period of at least several minutes. Variants in which the voltage is raised continuously to flashover are not standardized but may be used for special purposes. NOTE 2 In testing of full scale insulators for system voltages above 800 kV, the solid layer method may be the preferred choice because of lack of experiences and possible difficulties for the salt fog method. More information on the solid layer method for such insulators is given in Annex E. 4.3 Arrangement of insulator for test
Test configuration 4.3.1The insulator shall be erected in the test chamber, complete with the metal fittings which are invariably associated with it. The vertical position is in general suggested for comparison of different insulator types. Tests in other positions (inclined, horizontal) duplicating actual service conditions may be carried out when agreed between the manufacturer and the user. When there are special reasons not to test insulators in the vertical position (e.g. wall bushings and circuit-breaker longitudinal insulation), only the service position shall be considered. The minimum clearances between any part of the insulator and any earthed object other than the structure which supports the insulator and the columns of the nozzles, when used, shall be not less than 0,5 m per 100 kV of the test voltage and in any case not less than 1,5 m. The configurations of the supporting structure and the energized metal parts, at least within their minimum clearance from the insulator, shall reproduce those expected in service. SIST EN 60507:2014

60507 © IEC:2013 – 11 – As regards the influence of capacitive effects on the test results, the following considerations can be drawn from the available experience: – fittings are deemed not to affect the results significantly, at least for test voltages up to 450 kV; – internal high capacitance can have some effect on the external surface behaviour, particularly in tests with solid layer methods at low pollution severity values.
Cleaning of insulator 4.3.2The insulator shall be carefully cleaned so that all traces of dirt and grease are removed. After cleaning, the insulating parts of the insulator shall not be touched by hand. The surface of the insulator is deemed to be sufficiently clean and free from any grease if large continuous wet areas are observed after rinsing. In the case of the solid-layer method, before the first contamination, scrubbing with a slurry of water and inert material such as kaolin shall be done, after which the insulator shall be thoroughly rinsed with tap water. A detergent may be added to the slurry. Before every subsequent contamination, the insulator shall again be thoroughly washed with tap water only. Hand wiping might be necessary, if either the SDD-levels or the test results become inconsistent. In the case of the salt-fog method, water, preferably heated to about 50 °C, with the addition of trisodium phosphate or other detergent, shall be used, after which the insulator shall be thoroughly rinsed with tap water. Before this final treatment, scrubbing as for the solid-layer method may be done if necessary. NOTE 1 When the volume conductivity of tap water is higher than 0,1 S/m, the use of demineralized water is recommended. NOTE 2 If necessary, the metal parts and the assembling materials can be painted with a salt-water resistant paint to ensure that no corrosion products wash down on to the insulating surface during a test. 4.4 Requirements for the testing plant
Test voltage 4.4.1The frequency of the test voltage shall be between 48 Hz and 62 Hz. In general the test voltage coincides with the highest voltage (phase to earth value) the insulator is required to withstand under normal operating conditions. For equipment, it is equal to Um/√3,Um being the highest voltage for equipment (see IEC 60071-1). It is higher than this value when testing insulators for phase to phase configurations or for isolated neutral systems.
Atmospheric corrections 4.4.2No humidity correction factor shall be applied. Test voltages shall be corrected for air density according to IEC 60060-1. The coefficient m is however still under investigation. NOTE 1 The temperature in the test chamber for relative air density calculation is the temperature measured at the height of the test object prior to the test. NOTE 2 The coefficient m depends on many factors such as pollution severity and insulator characteristics. For the time being provisionally reference can be made to value m=0,5 [1]. NOTE 3 Atmospheric correction factors for polluted insulators are presently under consideration by CIGRE SC D1. SIST EN 60507:2014

– 12 – 60507 © IEC:2013
Minimum short-circuit current 4.4.3In the artificial pollution tests, the testing plant needs a short-circuit current (Isc) higher than in other types of insulator tests to ensure that the voltage drop during the test is small and has no influence on test results. This means that Isc must have a minimum value which varies with the test conditions; moreover there are also requirements on other parameters of the testing plant. The minimum value of Isc (Isc min) is given in Figure 1 as a function of the electrical surface stress of the insulator under test, expressed in terms of its unified specific creepage distance. Besides the above requirement of Isc min value, the testing plant shall comply with the two following conditions: – resistance/reactance ratio (R/X) equal to or higher than 0,1; – capacitive current/short-circuit current ratio (SCCII) within the range 0,001 – 0,1. More information on the criteria followed to assess the above requirements is given in Annex A. When the value of Isc of the testing plant, although higher than 6 A, does not comply with the limits given in Figure 1, the verification of a specified withstand characteristic of a polluted insulator (see 5.6 and 6.8) or the determination of its maximum withstand characteristic (see Annex B) can still be performed, provided that the source validity is directly ascertained by the following check. In each individual test of this investigation, the highest leakage current pulse amplitude is recorded and its maximum value (Ih max) determined considering the three tests resulting in withstand, in the withstand conditions. The Ih max value shall comply with the expression below: 11hmaxSC≥II Isc being given in r.m.s. and Ih max in peak value. More details are given in Annex A. Since the leakage currents can be used for the interpretation of the results, it is recommended that suitable devices be arranged in order to record these currents during artificial pollution tests. SIST EN 60507:2014

60507 © IEC:2013 – 13 –
0 2 4 6 8 10 12 14 16 18 10 15 20 25 30 35 40 45 50 USCD
(mm/kV) Minimum short-circuit current Isc min (Arms) IEC
2985/13
mm/kV Arms USCD < 28 28 ≤ USCD ≤ 45 Isc min = 6 Isc min = |USCD/√3| – 10 Figure 1 – Minimum short-circuit current, Isc min, required for the testing plant as a function of the unified specific creepage distance (USCD) of the insulator under test NOTE The available experience is deemed insufficient to give Isc min values for tests at unified specific creepage distances higher than 45 mm/kV. 5 Salt fog method 5.1 General information The salt fog test procedure simulates type B pollution (see IEC 60815-1) where a liquid conductive layer covers the insulator surface. In practice, this layer does not contain any significant insoluble material. The degree of pollution in a test is defined by the salinity of the salt fog expressed in kg of salt (NaCl) per m3 of water. The test consists of two parts – preconditioning process (the aim of which is cleaning of the tested insulator surface) and withstand test. The detailed description of both procedures is given in 5.5 and 5.6. NOTE The salt fog test method is not recommended for tests of insulator configurations at higher system voltage (800 kV and above). The main reason is that the specified distance between tested insulator and spraying nozzles (5.3) may be not sufficient for higher test voltages; in the frame of the recent revision with respect to the extension to the UVH range the specified distance between tested insulator and spraying nozzles was kept at 3 m in order to maintain the validity of test results with previous version of this standard. 5.2 Salt solution The salt solution shall be made of sodium chloride (NaCI) of commercial purity and tap water. NOTE Tap water with high hardness, for example with a content of equivalent CaCO3 greater than 350 g/m3, can cause limestone deposits on the insulator surface. In this case the use of deionized water for preparation of the salt solution is recommended. Hardness of tap water is measured in terms of content of equivalent CaCO3). SIST EN 60507:2014

– 14 – 60507 © IEC:2013 The salinity used shall have one of the following values: 2,5 – 3,5 – 5 – 7 – 10 – 14 – 20 – 28 – 40 – 56 – 80 – 112 – 160 and 224 kg/m3. The maximum permissible tolerance in salinity is ±5 % of the specified value It is recommended that the salinity be determined either by measuring the conductivity or by measuring the density with a correction of temperature. Table 1 gives the correspondence between the value of salinity, volume conductivity and density of the solution at a temperature of 20 °C. When the solution temperature is not at 20 °C, conductivity and density values shall be corrected. The temperature of the salt solution shall be between 5 °C and 30 °C, since no experience is available to validate tests performed outside this range of solution temperature. Table 1 – Salt-fog method: correspondence between the value of salinity,
volume conductivity and density of the solution at a temperature of 20 °C Salinity Volume conductivity
Density
Sa σ20 ∆20 kg/m3
S/m
kg/m3 2,5
0,43
– 3,5
0,60
– 5
0,83
– 7
1,15
– 10
1,6
– 14
2,2
– 20
3,0
– 28
4,1
1 018,0
5,6
1 025,9
7,6
1 037,3
1 052,7
112 13
1 074,6
1 104,5
1 140,0
The conductivity correction shall be made using the following formula: σ20 = σθ [1 – b (θ – 20)] where: θ
is the solution temperature (°C) σθ
is the volume conductivity at a temperature of θ °C (S/m) σ20 is the volume conductivity at a temperature of 20 °C (S/m) b
is the factor depending on solution temperature θ, as obtained by the following equation, and as shown in Figure 2: b = 3,200 × 10-8θ3 + 1,032 × 10-5θ2 – 8,272 × 10-4θ + 3,544 × 10-2 SIST EN 60507:2014

60507 © IEC:2013 – 15 –
0,015 0,02 0,025 0,03 0,035 5 10 15 20 25 30 35 θ
(°C) b IEC
2986/13
Figure 2 – Value of factor b as a function of solution temperature The density correction shall be made using the following formula: ∆20 = ∆θ [1 +
(200 + 1,3 Sa) (θ – 20) × 10–6] where: θ
is the solution temperature (°C) ∆θ is the density at a temperature of θ °C (kg/m3) ∆20
is the density at a temperature of 20 °C (kg/m3) Sa
is the salinity (kg/m3) This correction formula is only valid for salinities over 20 kg/m3. 5.3 Spraying system The fog is produced in the test chamber by means of the specified number of sprays which atomize the solution by a stream of compressed air flowing at right angles to the solution nozzle. The nozzles consist of corrosion resistant tubes, the internal diameter of the air nozzles being 1,2 mm ± 0,02 mm and the internal diameter of the solution nozzle being 2,0 mm ± 0,02 mm. Both nozzles shall have an outside diameter of 3,0 mm ± 0,05 mm and the ends of the nozzles shall be square-cut and polished. The end of the solution nozzle shall lie on the axis of the air nozzle to within ±0,05 mm. The distance between the end of the compressed air nozzle and the central line of the solution nozzle shall be 3,0 mm ± 0,05 mm. The axes of the two nozzles shall lie in the same plane to within ±0,05 mm. Figure 3 shows a typical construction of the fog spray nozzle. The sprays shall be in two columns parallel to and on opposite sides of the insulator which shall have its axis in the same plane as the columns, i.e. a vertical insulator is tested with vertical columns and a horizontal insulator with horizontal columns. In the case of an inclined insulator (see Figure 4) the plane containing the insulator and the columns shall intersect the horizontal plane in a line at right angles to the insulator axis; in this case, the axis of the solution nozzles is vertical. The distance between the solution nozzles and the insulator axis shall be 3,0 m ± 0,05 m. The sprays shall be spaced at 0,6 m intervals, each spray pointing at right angles to the column axis towards its counterpart on the other column and within an angle of 1° to the plane of the sprays. This alignment can be checked for vertical sprays by lowering the solution nozzle, passing water through the air nozzle and directing it towards the opposing spray; SIST EN 60507:2014

– 16 – 60507 © IEC:2013 afterwards, raising the solution nozzle to the operating position. The midpoint of the insulator shall preferably be in line with the mid-points of the columns of sprays. Both columns shall extend beyond each end of the insulator by at least 0,6 m. The minimum number N of sprays per column shall be, for a length H in metres of the insulator: 30,6+=HN The sprays shall be supplied with filtered, oil-free air at a relative pressure of 700 kPa ± 35 kPa. The flow of solution to each spray shall be 0,5 dm3/min ± 0,05 dm3/min for the period of the test, and the tolerance on the total flow to all sprays shall be ±5 % of the nominal value.
60507 © IEC:2013 – 17 –
30 13,2 ± 0,05 3 ± 0,05 ref. 14,2 ± 0,05 30 Block Mounting holes See NOTE 5 62 Section A-A showing nozzles in position Both nozzles to have a close sliding fit within block See NOTE 4 62 38 A A See NOTE 3 Tapped holes for locking screws All dimensions in millimetres
Drill and tap ¼ NTP 3 ∅3 ∅11,5 ref. ∅15,9
Drill and tap ¼ NTP 3 ∅3 ∅12,7
∅15,9 28 42 Drill ∅1,2 thru’ 60° inclusive angle Drill ∅2 thru’ 60° inclusive angle 10,2 14,2 28 46 Compressed air nozzle Salt water nozzle IEC
2987/13 Compressed air nozzle Salt water nozzle
NOTES: 1
Machine all over ± 0,1 mm, unless stated otherwise 2
Concentricity of nozzles within 0,1 mm 3
Outer face both nozzles to be square and polished 4
Finishing of holes in block with a sized milling cutter is suggested to achieve best fit 5 Remove all sharp edges except as NOTE 3 above 6 Mounting holes should be drilled thru’ to allow unit to be positioned from either side 7 Unit should be initially be assembled with nozzle shoulders flush with inboard surfaces of block as shown above if required, small adjustments in the positioning of the nozzles can be made to optimize spray properties
Hardware requirements: 2 off stainless steel fitting with hose barb Swagelok number SS-4-HC-1-4 2 off stainless steel set screw (as required) Rubber hose as required with retaining clamps. Stainless steel mounting hardware (as required) Material requirements: Salt water nozzle: Stainless steel Type 303 Compressed air nozzle: stainless steel Type 303 Block: non absorbant plastic*
*POM (polyoxymethylene) is recommended for ease of machining and dimensional stability Figure 3 – Typical construction of fog spray nozzle SIST EN 60507:2014

– 18 – 60507 © IEC:2013
0,6 m α α 90° 3 m 3 m α Spray nozzle positions Direction of spray Solution nozzle axis: vertical Test insulator α
angle of inclination IEC
2988/13
Figure 4 – Test layout for inclined insulators 5.4 Conditions before starting the test The test shall start while the insulator, cleaned according to 4.3.2, is still completely wet. At the start of the test the insulator shall be in thermal equilibrium with the air in the test chamber. In addition, the ambient temperature shall be not less than 5 °C nor greater than 40 °C and its difference from the temperature of the water solution shall not exceed 15 K. The insulator is energized, the salt-solution pump and air compressor are switched on, and the test is deemed to have started as soon as the compressed air has reached the normal operating pressure at the nozzles. 5.5 Preconditioning p
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