Phi Bushing Filtering & Bypass Valves - GE PHI 530.1425.2500 Operating And Maintenance Instructions Manual

Each instrument is equipped with 4 Normally Open micro-switches that provide alarm / tripping signals. Table
10 shows the micro switches purpose and the pressure set up.
Micro switch
Low pressure
Tripping
Low pressure
Alarm
High pressure
Alarm
High pressure
Tripping
The pressure gauge is installed on a ball type valve for easy replacement in case on need and all electrical
cables are wired in the junction box provided with DIN type terminal blocks (see Appendix 2).
Additional information about the oil pressure gauge device are in illustrated in Appendix 5.
6.3 PHI Bushing filtering & bypass valves
PHI bushings are equipped with a special valve system located at the level of the central flange that allows:
The oil filling under vacuum.
•
The oil recirculation for filtering and the oil passage during the normal operation.
•
NOTE: Operation on the valves must be done by qualified and authorized operators only.
Depending on their specific function, they are named filtering and by-pass valves (see Figure 10). These valves
are installed inside some metallic protrusions on the bushing flange, protected by metal lids (see Figure 11).
The number of valve blocks is related to the size of the bushing.
HVDC TRANSFORMER BUSHINGS
Figure 9 – Oil pressure gauge
Description
Too low pressure for operation
Low pressure related to low oil
level
Overpressure inside the OIP
section
Too high pressure inside the
OIP section for operation
Table 10 – Alarm and tripping micro switches set-up
PHI 530.1425.2500
PHI 265.850.1500
Kepco project
Pressure set up
[bar gauge]
0.2
0.4
2.6
2.8
IS 2664 GB
Page 19 of 70
[MPa gauge]
0.02
0.04
0.26
0.28