10 percent of all insulators on Algerian transmission liens will soon be composite type.
Table 7: Axial & Unified Creepage Distance (USCD) Criteria at GRTE, 220 kV Composite Versus Glass Insulators Glass System Voltage
SiR
Number of discs
Type or Reference
USCD mm/kV
USCD mm/kV
Axial Distance (m)
18
U160P
70
80
3.060
18
U160A
46
57
2.628
18
U120A
46
60
2.340
21
U120A
53
68
2.73
20
U120A
51
59
2.600
18
U120P
56
58
2.628
220 kV
Table 8: Development of Composite Insulator Usage at GRTE (2002-2012) Year
2002
2006
2008
2010
Proj. 2012/2013
Total Network Length
14,635
17,403
21,683
22,232
2,000,000 Glass discs
Number of New Insulators/Year
4400
1704
1312
3801
6000 SiR units
Length of Lines with Composite Insulators (km)
306
475
913
1184
Evolution
2%
3%
4.2%
5.3%
10% (objective)
Table 9: Growth in Application of Live Washing from Helicopters by GRTE
52
Live Line Washing
2009
2010
2011
Development 2011/2010
By truck (No. glass strings washed)
4,503
4,684
3,730
-21%
By Helicopter (No. glass strings washed)
-
4,170
12,872
+ 209%
INMR® Q2 2012
INMR Issue 96.indd 52
algErian grid opErator FocusEs
on
challEngEs
using helicopters saved the high cost of moving heavy trucks and logistical equipment into areas without ease of access by road. Says Louaked, “helicopter-based live line washing ended up costing 7 times less than from trucks, simply because of the efficiency with which the work could be done.” For example, he indicates that the average number insulators strings washed each day by helicopter has been about 200 whereas in the case of tanker trucks this figure rarely exceeded 15 for each washing crew. That means that washing 200 strings by truck over the same time
“From our perspective, some prudence is still required when it comes to composite insulators and we keep in mind what would happen if all such insulators began to fail over the same short time frame.”
oF
harsh sErvicE EnvironmEnt
16/05/12 2:40 PM