R. Suzuki
36-WG11/Leatherhead/178
January 2004
Comments on Document 36-WG11/Vichy/EC2 (Part 2) Followings are the comments on the Document 36-WG11/Vichy/EC2. Clause 8
Paragraph
Type of
Figure/Table
comment
Text and
Technical
Figures
9.1
Text
Technical
9.2 &
Tables 1-4
Technical
10.1
and Kps
10.2
Correction
Technical
factor Kad
10.3-7
Correction Factor Ksp, Kld, Kos, Ka and Kcf
Technical
COMMENTS
Proposed change
Reference USCD should be determined basing on technical data (see Doc. 138). It would be different from SCD in the existing IEC 60815, because SPS classes do not exactly correspond to the existing IEC classification. Actually if Reference USCD in the draft is applied for the reference cap and pin insulator, the determined leakage distance will be not sufficient for some parts in SPS classes “d” and “e” as shown in Figure A of the attachment (1). Thus it is proposed to modify the Reference USCD for SPS classes “d” and “e” as shown in the attachment (1). A new table is proposed resuming pros & cons of each profile in vertical and horizontal positions. It was decided at the last WG meeting that table 1-4 should be replaced by the figures from CIGRE C4.13.01. But they do not include alternating shed profile. Thus modified figures including recommended Kps are proposed. For cylindrical insulators, a lot of data regarding the effect of average diameter were gathered and analyzed by the Electric Technology Research Association (ETRA) in Japan as shown in Figure B of the attachment (1). Comparing the investigation results and the new Reference USCD proposed above, it is clear that the modified Reference USCD well corresponds to the required leakage distance for the long rod insulator having average diameter of approx. 300mm as shown in Figure C of the attachment (1). Now we agree with that Kad should be 1.0 for average diameter 300mm, but actually the relationship between average diameter and leakage distance/kV is not linear as shown in Figure B. Thus it is proposed to modify the correction factor for insulator diameter Kad as shown in the attachment (4). The correction factor shall be specified basing upon technical data. However, sufficient technical data corresponding to the dotted lines shown in the attachment (5) are not available. Thus the note shall be included in order to remind the users to confirm the performance of the candidate insulator by evaluation tests if the dotted lines are adopted. (Or just a limitation shall be specified like the existing IEC 60815.)
See attached (1).
1
See attached (2). See attached (3).
See attached (1) and (4).
See attached in (5).
Proposed changes (in red) to Draft IEC 60815-2 (36-WG11/Vichy/EC2) (1) Page 8, Clause 8 Determination of the reference USCD
Reference USCD (mm/kV)
Figure 1 shows the relation between SPS class and reference USCD for glass and ceramic reference insulators. The values shown cover the highest pollution of each SPS classes are preferred values representative of mid-class SPS. If exact SPS measurements are available, it is recommended to take a reference USCD which corresponds to the position of the SPS measurements within the class. For example the example E6 given in figure 1 of IEC 60815-1 would have a reference USCD of 47 mm/kV.
70
67
60 50
47
40
35
30
28 22
20 10
a1
b2
3c
4d
5e SPS Class
Figure 1 – Reference USCD as a function of SPS class NOTE 1
If higher SPS is anticipated compared with very heavy class the reference USCD shall be increased accordingly.
NOTE 2
In case of very light and light classes, insulator string length depends on the other factor like a insulation coordination
(lightning and switching impulse characteristics).
Reference cap & pin insulator 70
2
NSDD:0.1mg/cm 60 Proposed USCD
L/E(USCD), 50 mm/kV 40 30
e:67 d:47
c:35 b:28
Draft USCD
a:22
20 10 0 0.001
Fig. 2-7: CIGRE Brochure 158 0.01
0.1 ESDD, /
2
0.5
1
2.5
10
Figure A – Relationship between ESDD and USCD under artificial pollution withstand voltage test (Reference Cap and pin insulators)
2
70 NSDD:0.1 mg/cm
60
L/E(USCD), mm/kV 50
2
d:47 Proposed USCD
40 30
e:67
c:35 b:28 a:22
20 10
Cylindrical insulator : ETRA Vol.35, No.3 Ave. Diam.: 300 mm
0 0.001
1.25 0.01
0.1 ESDD, mg/cm
1
2
Leakage Distance per 5% Flashover Voltage, L/E5 (mm/kV)
Figure B – Relationship between ESDD and USCD under artificial pollution withstand voltage test
Average Diameter, D(mm) Figure C – Relationship between average diameter and leakage distance for 5% FOV (Reference: Fig. 3-6 in ETRA Vol.35, No.3, 1979)
3
(2)New table in clause 9.1 General recommendations for profiles
Pros
Vertical Cons
Pros
Horizontal Cons
Open profile Collects less pollution, as the aerodynamic profile gives good self-cleaning by wind.
Total surface collects more pollution under rapid pollution condition, such as seasonal wind, typhoon, etc.
Standard profile
Anti-fog profile Deep under-rib prevents wetting of whole under side during rain.
－
Long creepage distance per disc or unit length. Shallow under-ribs collect More wind borne deposit wind-borne deposits. accumulates on the under-side due to Needs a relatively long reduced self-cleaning. string length.
Needs a long string length. Collects less pollution, as Collects less pollution Long creepage distance the aerodynamic profile because of self-cleaning per disc or unit length. gives good self-cleaning by wetting. by wetting and wind.
Total surface collects more pollution under rapid pollution condition, such as seasonal wind, typhoon, etc.
Total surface becomes Wind borne deposit polluted but is accessible accumulates on the for natural cleaning. surface with deep under-rib due to reduced Needs a relatively long self-cleaning. string length.
Needs a long string length.
4
Alternating profile Collects less pollution, as the aerodynamic profile gives good self-cleaning by wind. Long creepage distance per disc or unit length. Total surface collects more pollution under rapid pollution condition, such as seasonal wind, typhoon, etc.
Collects less pollution, as the aerodynamic profile gives good self-cleaning by wetting and wind. Long creepage distance per disc or unit length. Total surface collects more pollution under rapid pollution condition, such as seasonal wind, typhoon, etc.
(3) Modified figures of Tables 1-4
Table 1 S election of profile for verticaland horizontala.c.cap and pin insulators P olltion area
K ps
S tandard profile
A nti-fog profile
O pen profile
A lternating profile
1.1 D esert
1.0
▲ ▲ ▲
0.9
▲
Vertical Horizontal
▲
Vertical Horizontal
▲
0.8 1.1 C oastal
1.0
▲■
▲
■
▲
0.9
▲■
■
■
0.8 1.1 Industrial
1.0
■
▲ ■
▲
▲
0.9
■ ■ ▲
0.8 1.1 A guricultural
1.0
▲
▲ ▲
0.9
▲
0.8 1.1 Inland (Low pollution)
1.0
▲
▲
▲
0.9 0.8
▲：Type A P ollution ■：Type B P ollution
5
▲
Table 2
P olltion area
S election of profile for verticaland horizontallong rod, post and hollow insulators K ps
S tandard profile
O pen profile
1.1 D esert
1.0
A nti-fog profile ▲
▲
▲
A lternating profile
▲
0.9 0.8 1.1
C oastal
1.0
▲
▲
▲ ▲
0.9 0.8 1.1
Industrial
1.0
▲
▲
▲
▲
0.9 0.8 1.1
A guricultural
1.0
▲
▲
▲
▲
▲
▲
0.9 0.8 1.1
Inland (Low pollution)
1.0
▲
0.9 0.8
▲：Type A P ollution ■：Type B P ollution
6
▲
(4) Page 14 Clause 10
Correction of the reference USCD
10.2 Correction for insulator diameter Kad Kad = 0.1021Da 0.4 Where Da = (2Dt + Ds1 + Ds2)/4
(Ds1=Ds2 for plain sheds)
1.6 1.5 1.4 1.3 Kad
1.2 1.1 1 0.9 0.8 0.7 0.6 0
NOTE
100
200
300
400 500 600 A ve.D iam .,m m
700
800
900
In case artificial pollution withstand/flashover voltage test is required, various factors, such as less pollution accumulation effect
with diameter, kinds of pollutants, etc. shall be considered by agreement between user and supplier.
1.6 1.5 1.4
ET R A 35-3 K ad=0.1021D a0.4
1.3 Kad
1.2 1.1 1 IEC D raft
0.9 0.8 0.7 0.6 0
100
200
300
400 500 600 A ve.D iam .,m m
7
700
800
900
(5) Page 14 to 16 Clause 10.3 to 10.7 Correction of the reference USCD 1.6
1.5 1.4
1.5
R ib shed
1.4 1.3
1.2
K ld
K sp
1.3
1.1
1.1
N o-rib shed
1
1.2
1
0.9
0.9
0.8
0.8
0.4
0.5
0.6
0.7
0.8
0.9
0
1
2
4
8
l/d
s/p
Correction factor, Ksp
Correction factor, Kld 1.3
1.3 1.25
1.25 1.2
C
