HVDC TRANSFORMER BUSHINGS
PHI 530.1425.2500
PHI 265.850.1500
Kepco project
IS 2664 GB
Page
17
of
70
6
Bushing oil characteristics and accessories
The PHI bushings are filled
Nynas Nytro 4000 A
mineral oil.
The same type of oil must be used in case of re-
filling or oil reprocessing.
At the end of the drying and impregnation process in GE factory, the bushing oil parameters are in accordance
with the data listed in the following
Table 8
.
Parameter
Limit
Water content by Karl Fisher at 20°C
≤
2 ppm
Breakdown voltage on 2.5 mm gap
≥
80 kV
Total gas content
≤
200 ppm (0.02%)
Total combustible gases
< 10 ppm (0.001%)
Power factor at 90°C
≤
0.0025
Resistivity at 30°C
≥
15 10
12
Ohm x m
Particle content
ISO11218 Class 00
Table 8 – Oil parameters for final oil filling and recirculation at the factory production
Concerning the ISO 11218 solid contamination limits classes, next
Table 9
summarizes the quantities and the
size limits for each class.
Classes
Maximum Contamination Limits (particles/100ml)
ISO 11218
> 4
µ
m(c)
> 6
µ
m(c)
>14
µ
m(c)
> 21
µ
m(c)
> 38
µ
m(c)
> 70
µ
m(c)
000
195
76
14
3
1
0
00
390
152
27
5
1
0
0
780
304
54
10
2
0
1
1560
609
109
20
3
1
2
3120
1220
217
39
6
1
3
6250
2430
432
76
11
2
4
12500
4960
864
152
22
4
5
25000
9730
1730
306
45
8
6
50000
19500
3460
6012
90
16
7
100000
38900
6920
1220
180
32
8
200000
77900
13900
2450
360
64
9
400000
156000
27700
4900
720
128
10
800000
311000
55400
9800
1440
256
11 1600000
623000 111000 19600
2880
512
12 3200000 1250000 222000 39200
5760
1024
Table 9 – Solid contamination limits classes according ISO 11218
NOTE:
The excellent quality of the oil process in the factory is such that the bushing does not require any
additional oil treatment before the transformer tests or before the installation on site.