36B(Stockholm/WG11)09 2000-09
INTERNATIONAL ELECTROTECHNICAL COMMISSION TECHNICAL COMMITTEE 36 : INSULATORS ______ IEC 36/WG11 – Progress report and comments on 36/178/INF Project 60815 Revision of IEC 60815 : Guide for the selection of insulators in respect of polluted conditions Progress Report No. 2 Since the last TC 36 meeting held in Houston WG11 has held four meetings: • April 1999 Mannheim • October 1999 Warsaw • January 2000 Vienna • September 2000 Stockholm A further meeting will be held on 22/09/2000 to take into account any discussion/decisions arising from the TC 36 meeting and to continue drafting. It is expected that meetings will continue to be held on a twice-yearly basis. Close cooperation is ensured with CIGRE WG33.13 and TF33.13.01 and TF33.13.03. Membership has evolved slightly with the addition of members from South Africa and China. The WG has produced a report and preliminary draft of the work so far which was circulated as 36/173A/DC. Those who wish to follow the work can visit the WG11 web site at http://clumb.free.fr The study of the compiled comments in 36/178/INF has been most constructive and has greatly helped WG in re-thinking philosophy and improving the draft. Notably it has been decided to add a method of site severity evaluation for conductive fogs. The comments from WG11 on the NC comments are reproduced hereafter. Clive Lumb September 2000
National Clause/ Committee Subclause
Paragraph Figure/ Table
Type of comment (General/ Technical/Edit orial) Editorial
Portugal
General
Spain
General
United Kingdom France
General
Germany
Introductory note
Italy
1
1 line
Editorial
United States of America Germany
1
Paragraph 6
Editorial
1
Page 4 nd 2 par
Editorial
United States of America
General
4
Editorial st
Editorial
COMMENTS
Date
Document
2000-09-20
36/173A/DC
Proposed change
Comment noted with thanks
The Portuguese National Committee agrees with document, with the following suggestion: use comma in numeric values instead of points. The Spanish National Committee has no comments on the text. UK may submit comments at the Stockholm meeting The French National Committee support the revision of the IEC 60815; 1986. The French National Committee approve the introduction of the NSDD value in addition of ESDD to characterize the pollution severity. The French National Committee consider the modification of the geometrical parameters as a priority The publication number must be changed “IEC 60815” instead of “IEC 60915” The meaning of the terms “dimensioning’’ and “design” would be clarified. Their use on the same sentence could be misleading and contradictory. “The aim this guide” should be corrected. “glass fibre core” is not a technical term, the load bearing part of a composite insulators consists of a polymeric matrix system that is axially reinforced by glass or synthetic fibres “TOV: 50 Hz temporary over voltage” should be generalized to also cover 60 Hz.
Page 2
OBSERVATIONS OF WG11 on each comment submitted
The support is noted
Change to “IEC 60815”
Proposal would be to delete the statement “but not the design” and clarify the term “dimensioning” (for example: determining the suitable creepage distance) “The aim of this guide”
Agreed – leads to confusion. Suggest: “This guide is applicable to the selection of insulators, and the determination of their relevant dimensions, to be used …” Agreed
Change “glass fibre core” into “fibre reinforced core”
Agreed. However, suggest taking up definition from PR 62217 ”… whereas polymeric insulators have an insulating body consisting of one or more organic based materials.”
“TOV: Temporary over voltage”
Agreed – Also allows for d.c. TOV
36(Stockholm/WG11)y
National Clause/ Committee Subclause
United States of America
5
Australia
5.1
Germany
5.1
United States of America Germany
5.2.3
6
Paragraph Figure/ Table
Page 5
Page 8
Type of comment (General/ Technical/Edit orial) Technical
COMMENTS
Proposed change
Ribs are briefly mentioned as Add additional sections regarding the contributing to pollution improved pollution performance of fog performance, but not significantly bowl or high-leak designs. and not in terms of the protected leakage distance they may provide. Surface condition is emphasized. The existing history with porcelain would indicate that leakage distance combined with protected leakage distance are significant factors in an insulator’s contamination performance. The voltage gradient also has an impact on the pollution flashover mechanism.
The information concerning relative merits of different shed profiles in various conditions will be given later in clause 9 of this draft and in parts 2 – 5 of 60815.
Agreed. Suggest adding this in a list of main parameters affecting pollution performance.
Suggest waiting until the final status of the Publication is known. Suggest changing title to “Brief introduction to basic pollution flashover mechanisms”. Suggest also adding “For a more complete description, refer to CIGRE 158”. “The required minimum specific creepage Agreed distance”.
Technical
This section provides useful information but can not be a normative text
Editorial
“The required minimum specific distance” should be corrected
Technical
It shall be made clear that pollution Please consider in Clause 3 “Definition” in the sense of this standard shall mean natural pollution only. Also, a clear distinction shall be made between pollution conditions at specific sites (pollution level) and pollution on an insulator surface. Further, it shall be made clear that testing is not within the scope of this standard.
Page 3
OBSERVATIONS OF WG11 on each comment submitted
Text shall become an appendix (informative)
Agreed : Suggest using the term “environmental” rather than “natural” Necessary definitions will be added.
36(Stockholm/WG11)y
National Clause/ Committee Subclause
Paragraph Figure/ Table
Czech Republic
The list of in situ method of measurement s
6.1.3
Type of comment (General/ Technical/Edit orial) Technical
Technical The fifth paragraph from the bottom of the page 9
Technical
Before the fourth paragraph from the bottom of the page 9 Germany
Germany
6.1.3
6.1.3
Page 9
Page 9 nd 2 par
Technical
Technical
COMMENTS
Proposed change
OBSERVATIONS OF WG11 on each comment submitted
At the beginning of the list to add the one more method, that is used in some countries for evaluation of pollution severity
• analysis of sediments collected in gauges (evaluation of amount of sediments, conductivity of soluble components etc.)
Agreed – First line of list can be modified in this manner.
After adding the new method it is necessary to change the beginning of the first sentence “The first two methods......
“The first three methods .....
Not necessary
The results of evaluation of pollution severity obtained by in situ measurement methods based on measurements on sample insulators are valid for given insulator type only. The different insulator types (anti-fog, long rod, aerodynamic, etc.) have the different behaviour under pollution.
The standard insulator shape is intended to form a means of site severity evaluation for Standardisation. These site severity measurements can be supplemented by measurement of the behaviour of different profiles in order to evaluate their performance with respect to the site/pollution conditions.
Add new paragraph after “Information on wetting shall be obtained”:
Agreed: But also need to add orientation as a factor. Also suggest adding that such factors are included in the dimensioning process given in parts 2-5.
The result of evaluation of pollution severity based on the measurement on sample insulators is influenced by insulator shape. For example in desert conditions the amount of sediments on aerodynamic insulator is smaller than on anti-fog or standard insulators. To add the following paragraph: It shall be added that the accumulation of pollution and self cleaning properties strongly depend on insulator type, material and shed profile.
In some areas, for example arid areas, it will be necessary to measure for a period of at least 3 years
Page 4
“The accumulation and self cleaning properties depend strongly on the insulators type, material and on the shed profile” Add note: “In some areas, for example arid areas, it will be necessary to measure for a period of at least 3 years”
Agreed In such cases a different approach may be necessary to save time. The WG will address this issue if data/time available.
36(Stockholm/WG11)y
National Clause/ Committee Subclause
Paragraph Figure/ Table
Italy
Figure 2
6.2
Type of comment (General/ Technical/Edit orial) Technical
COMMENTS
Proposed change
The influence of the NSDD on the quantitative evaluation of the pollution site severity value would seem to be too high and conservative in respect to insulator pollution performance. ENEL/CESI experience is that, in general, site pollution layers with higher NSDD values contain salts with low solubility (industrial, desert and agricultural pollution types) and, in laboratory tests, the criticity or flashover probability value of an insulator polluted with a suspension containing low solubility salts is lower than the one polluted with high solubility salts, under the same other conditions. This would be considered in the quantitative definition of the site pollution severity levels. Suggestion would be to provide laboratory and service insulator pollution performance data which have been considered for the quantitative definition of the site pollution severity levels shown in Figure 2.
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OBSERVATIONS OF WG11 on each comment submitted
This important topic is currently under review taking account of new information from CIGRE. It is foreseen that the graph will be revised. Any service experience from the NCs would be most welcome.
36(Stockholm/WG11)y
National Clause/ Committee Subclause
Italy
Paragraph Figure/ Table
6.2
Type of comment (General/ Technical/Edit orial) Technical
Italy
6.2
Table 3
Technical
Germany
6.2
Page 10
Technical
Germany
6.2
Page 10 st 1 par
Technical
COMMENTS
Proposed change
OBSERVATIONS OF WG11 on each comment submitted
Our opinion is that it would be suitable to have a quantitative definition of the pollution site severity levels using the three severity parameters normally adopted for the artificial pollution 3 tests: i.e. Salinity (kg/m ), Layer conductivity (µS) and Salt deposit 2 density (mg/cm ). These parameters are currently used for the selection and dimensioning of insulators for polluted conditions in different countries. Proposal would be to complete the figure of the quantitative site severity values by adding a Table with values (or range of values), expressed in terms of Salinity and Layer conductivity The meaning of the statement “At normal wind speed” needs to be clarified. Our opinion is that both wind speed and duration would influence the accumulation process of pollution on the insulator surfaces. Headline “Pollution severity level”. Insulators of different type and different material may behave different in the same environment. It is obvious that the same level of pollution may be more or less severe. Consequently the term “pollution level” shall not be mixed up with the term “severity”. It shall be made clear that there is not “very light pollution” and not “very heavy pollution” in an absolute meaning. We understand that these terms refer to site severities.
Proposal would be to add in Table 3 two columns with site pollution levels, as follows: 3 Salinity -Sa - in kg/m • Very light: 56
The WG recognises that for marine or other conductive fogs the ESDD/NSDD measurement is of lesser value and that an alternative method for site severity assessment is necessary.
Page 6
Layer conductivity – K – in µS:
Liaison with CIGRE TF33.13.03 (Monitoring) is in place to develop/choose a method (e.g. surface conductance or leakage current measurements).
To be defined by the WG
Suggestion would be to delete the statement “at normal wind speed” under the title of the second column Table.
Acceptable
Change headline to “Pollution level”.
We propose “Site severity” in order to avoid any confusion.
The first paragraph shall be changed as follows:
Agreed
“For the purpose of standardisation five levels of pollution characterising the site severity are qualitatively defined from very light pollution to very heavy pollution.”
36(Stockholm/WG11)y
National Clause/ Committee Subclause
Paragraph Figure/ Table
Germany
Page 10 Figure 2
6.2
nd
Type of comment (General/ Technical/Edit orial) Technical
Germany
7
2 par type of system”
Editorial
Germany
7
Editorial
Germany
7
Par. “Overvoltages” Par “Overvoltages”
Technical
COMMENTS
Figure 2 refers only to standard cap&pin insulators. Similar figures like figure 2 should be given for all insulator types and materials for ac and dc.
It is not necessary to provide information about the dc and ac behaviour at this place in the document. The particulars of the system types “DC” and “AC” will be further described in individual parts (part 2-5) of IEC60815. For the definition of TOVs refer to IEC60071-2 It is not clear what types of TOV have to be considered with respect to the flashover of polluted insulators.
Proposed change
OBSERVATIONS OF WG11 on each comment submitted
Add new figures that provide information and data for ceramic and composite longrod insulators.
It is agreed that it would help to have reference data for other “standard” types. The German expert has proposed to furnish the necessary information.
The diagrams shall be amended by data for long rod insulators. The title of figure 2 shall read as follow: “relation between ESDD/NSDD and site severity for standard glass and ceramic cap&pin insulators.” Suggest keeping the existing text, but Replace text by: “for the comparison of specific creepage adding that this effect is dealt with in distances of ac and dc systems it shall be detail in parts 2 to 5. noted that the creepage distance values are related to either the line to line voltage or the line to earth voltage.” Add reference to IEC60071-2
Agreed, for a.c. systems
Please specify under what conditions TOV shall be considered
We suggest adding reference to CIGRE 158 for more details on evaluating risks linked to TOV. Should be “grounded neutral”
Please specify the term “natural grounded system”
The term “natural grounded system” is not clear Germany
7
Australia
9
Par. Technical “reliability availability, maintainability (RAM)”
Such special features should not be part of a standard
The ratio of sheath diameter to shed diameter causes the surface current density to vary along an insulator and does influence the pollution performance. It is presumed that either form factor or profile factor will address this issue.
Page 7
Delete paragraph.
The WG feels that this concept is very important and is a way to point to better use of risk evaluation. Suggest also adding a reference to CIGRE 158. The WG is grateful for this input and will make sure that it is taken into account.
36(Stockholm/WG11)y
National Clause/ Committee Subclause
Paragraph Figure/ Table
Italy
Items b) and c) of page 16
A.3.1
Type of comment (General/ Technical/Edit orial) Technical
COMMENTS
Proposed change
ESDD measurements in sites would Suggestion would be to put the text of the be carried out with the same Sub-clause in line with the one given in accuracy adopted for the IEC 60507 measurements of SDD in laboratory
Page 8
OBSERVATIONS OF WG11 on each comment submitted
This procedure is intended for field use and therefore differs from that of IEC 60507. The WG members are currently evaluating this method by tests.
36(Stockholm/WG11)y
