W. Petrusch 10/02/03

36-WG11/Cavtat/149

Study of definitions/abbreviations by W. Petrusch, Proposed changes (in red) to Draft IEC 60815-1 (36-WG 11/Capetown/144): Page 8, bottom: The further parts 2-5 of IEC 60815 give specific guidance on: •

Determining the reference Unified Specific Creepage Distance (USCD) from Site Pollution Severity (SPS);

Page 10+, add new definitions: 3.x Highest leakage current ( i highest ) Highest peak value of the leakage current measured on an insulator at withstand conditions during a sufficient test period ( i.e. one or more years in case of outdoor test station or one hour in case of salt fog tests according to IEC 60507). I am not sure, if the following two new definitions are necessary: 3.y

Co-ordination pollution severity withstand level

The co-ordination pollution severity withstand level is the lowest value of the withstand severity of the insulation which will meet the performance criterion when it is subjected to the highest voltage for the equipment.

3.z

Required pollution severity withstand level

The required pollution severity withstand level is the co-ordination pollution severity withstand level converted to the appropriate conditions for the standard pollution withstand test. Change existing definitions: 3.6 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 U m /√3) It is generally expressed in mm/kV. 3.7 Form factor (FF) (different from 60507 :1993)

A factor determined from the insulator dimensions equal to the integral of the reciprocal value of the insulator circumference versus the partial creepage distance counted from the end of the insulator up to the point reckoned. (See Annex G) 3.12 Site Equivalent Salinity (SES) The salinity of a salt fog test according to IEC 60507 that would give comparable peaks of leakage current on the same insulator as produced at the same voltage by natural pollution at a site; generally expressed in kg/m³.

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W. Petrusch 10/02/03

36-WG11/Cavtat/149

Page 37, Annex C, second paragraph: In both the cases the calibration for the current values is made by a salt fog test according to IEC 60507 on the same insulator and at the same voltage stress. The tests are made with increasing salinity from test to test, until peak values of leakage current ( i highest ) comparable to those from the site measurement occur. The corresponding salinity is the Site Equivalent Salinity (SES).

Page 37, C1: This periodical measurement is performed at a low voltage on an insulator with a simple shed shape (e.g. Siemens-meter [4]) or a reference cap and pin or long rod insulator. The applied voltage shall be low enough (for example 700 V rms per metre of creepage distance) to avoid dry band arcing. The current values shall be recorded in a suitable way. Page 37, C2: This continuous measurement is performed on a string of reference cap and pin insulators or a reference long-rod insulator. Depending on the stress of the insulator the measurement will show only I highest values (no flashover during the test period) or I highest and I max values (flashover). The electrical stress used should put the insulator in withstand condition for the expected site pollution severity class, e.g. no pollution flashover should occur during the test period. The current values shall be recorded in a suitable way.

Proposed changes (in red) to Draft IEC 60815-2 (36-WG 11/Capetown/145): Page 6, middle: The aim of this Technical Specification is to give the user means to: •

Determine the reference Unified Specific Creepage Distance (USCD) from Site Pollution Severity (SPS);

3.1 Change as in Part 1 Unified Specific Creepage Distance (repeated from IEC 60815-1 for clarity) The creepage distance of an insulator divided by the maximum operating voltage across the insulator (for a.c. systems usually U m /√3) It is generally expressed in mm/kV.

Add new definitions as in Part 1: 3.y

Co-ordination pollution severity withstand level

The co-ordination pollution severity withstand level is the lowest value of the withstand severity of the insulation which will meet the performance criterion when it is subjected to the highest voltage for the equipment.

3.z

Required pollution severity withstand level

The required pollution severity withstand level is the co-ordination pollution severity withstand level converted to the appropriate conditions for the standard pollution withstand test.

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W. Petrusch 10/02/03

36-WG11/Cavtat/149

Page 7, lower half: • Verification of the dimensioning, in the case of Approach B, by laboratory tests (see Clause 12 annex A). Page 8, Clause 9.1: General recommendations for profiles (repeated from IEC 60815-1) Standard profiles (Figure 2) are effective for use in 'very light' to 'medium' polluted areas where a long creepage distance or aerodynamically effective profile is not required. Aerodynamic or open profiles (Figure 3) prove to be beneficial in areas where the pollution is deposited onto the insulator by wind, such as deserts, heavily polluted industrial areas or coastal areas which are not directly exposed to salt spray. This type of profile is especially effective in areas that are characterised by extended dry periods. Open profiles are also accessible for easy cleaning under maintenance. The use of steep anti fog profiles or shed profiles with deep under-ribs, (Figure 4) are beneficial in areas exposed to a salt water fog or spray, or to other pollutants in the dissolved state. These profiles may also be effective in areas with a particulate pollution precipitation containing slow dissolving salts. More recent flatter anti-fog profiles (Figure 5) with fewer or shallower under-ribs can be beneficial in areas of heavy industrial pollution, notably where string length is limited; however deep under-ribs should be avoided on horizontal insulators. Alternating long and short sheds (Figure 6) are beneficial in areas where heavy wetting can occur. Typical pin type shed profiles are shown in Figure 7.

Page 13, 10.2: For long rod, post and hollow core insulators correct for average diameter D ...................................................

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a m

by: