HVDC TRANSFORMER BUSHINGS
PHI 530.1425.2500
PHI 265.850.1500
Kepco project
IS 2664 GB
Page
8
of
70
4
Technical characteristics
PHI bushings are based on the hybrid technology. This means that the bushing is based on two different
insulation technologies: The first, based on an Oil Impregnated Paper (OIP in the document) grading capacitor,
realizes the interface with the transformer. The second, based on a gas insulated section, realizes the interface
to the converter plant.
The bushing, filled at rated filling pressure with pure SF6 gas, is designed to operate at low temperatures down
to -25° C.
The Hybrid solution offers the following advantages:
•
Complete separation between the gas compartment and the transformer turret. Gas leakages to the
transformer are not possible and they are detected by suitable pressure gauges at the level of the OIP
capacitor section.
•
Full prevention of transformer oil spills into the valve hall due to the particular bushing structure.
•
The mineral oil inside the grading capacitor OIP section provides an optimum cooling of the conductor
with excellent performances in case of high current ratings and harmonics presence.
•
The grading capacitor winding is 100% protected from the risk of pollution during the bushing installation
on the transformer, as it is fully sealed by special fibreglass barriers.
Next
Table 2
reports the main electrical technical characteristics of the two bushing types and
Table 3
reports
the design environmental conditions. The complete outline drawings of the two bushing types are shown in
Appendix 1
.
Bushing type
PHI 530.1425.2500
PHI 265.850.1500
Voltage ratings
Rated continuous d.c. voltage per valve bridge U
dm
Number of six pulses bridges in series N
Rated continuous a.c. voltage
Maximum continuous a.c. voltage U
vm
265
2
220
230
265
1
220
230
kVdc
kV line to line
kVrms
Current rating
Rated current
Distorted operation harmonics current
2500
See tech spec.
1500
See tech spec.
Arms
Short circuit level
34
34 kApk
Rated frequency
60
60 Hz
Lightning impulse withstand (BIL)
1425
850 kVpk
Chopped wave
1567.5
935 kVpk
Switching impulse dry withstand (SIL)
1217
745 kVpk
DC 2h voltage test
964
508 kVdc
Polarity reversal test
688
308 kVdc
Power frequency withstand (1 min)
679
405 kVrms
AC PD test (1 hour)
715
391 kVrms
Rated filling pressure @ 20°C
0.63
0.63 MPa abs
Table 2 – Bushing electrical characteristics
Содержание PHI 530.1425.2500
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