J. Wańkowicz
36-WG11/Milan/96
Relation between ESDD/NSDD and site severity for standard profile long rod insulators. Two types of standard profile long rod insulators were selected for field tests. LP 75/17 (or L 100 BE 895) – normal sheds and short creepage distance. LPZ 75/27W (or L 160CE 1160-27) – alternating sheds and long creepage distance Technical data for these long rod insulators is presented on their catalogue sheets attached to these test results. The tests were conducted in 4 different sites and they last up to 20 months. The insulators subjected to natural pollution were continuously connected to a phase voltage (about 63kV) of 110kV system. At least 8 pieces of each type of the insulators were tested in each site. ESDD were measured every month on selected surfaces of the two insulators of each type taking into account upper surface of sheds, pieces of shunks and lower surfaces of sheds. The ESDD value for an insulator was calculated as average value of the ESDD measured on the selected parts. These values fulfill long normal statistic. The highest ESDD values measured during the tests were applied to construct the drawing 1. 10
47 2, 5 85 0, 33 0,
HEAVY 1 0,
NSDD mg/cm2
95 0,
VERY
1
0,1
MEDIU M LIGHT
VERY LIGHT
ESDD mg/cm2
26
5
09
7
5
0,1
0,
0,
05
03
01
01
0,01
0,
0,
0,
0,
0,01 0,001
1
Pollution level, site description and ESDD/NSDD values Pollution level
Site description
The stand was located in the vicinity of a metallurgy copper plant IV - Heavy melt is applied. The natural contaminant deposited on examined insulators in the form of thick deposits may by characterized as so called insoluble substances like oxides (SiO2, AL2O3, FE2O3) and heavy metal sulfides. The remaining 5 to 20% of the dust consists of easily dissoluble sulfates of the CuSO4 type and hardly dissoluble carbonates of the MgCO3 type. III – Medium The stand was located in the vicinity of electric power plant. Lignite was used there as a fuel. The area is subjected to industrial smoke and fly ashes. II – Light The stand was located in the vicinity of heating plant. Coal was used there as a fuel. The plant was modernized and therefore its polluting activity was strongly reduced. I – Very The stand was located on the roof of HV hall at the Wrocław Light University of Technology about 40m over the level of ground. The university is located not far from a center of a large city.
ESDD mg/cm2
NSDD mg/cm2
LP75/17
LPZ75/27W
LP 75/17
LPZ 75/27W
0,09
0,26
0,86
2,5
0,065
0,09
0,62
0,86
0,037
0,055
0,33
0,49
0,015
0,075
0,012
0,06
