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HVDC TRANSFORMER BUSHINGS
PHI 530.1425.2500
IS 2664 GB
PHI 265.850.1500
Page 21 of 70
Kepco project
Filtering valves
¾" BSP
connections
By-pass valve
Protective
caps
Metal lid
Metal lid
By-pass valve
Filtering valves block
By-pass valve block
Figure 11 – PHI bushing valves and connections arrangement
The metal lids are provided with internal protrusions that prevent the flange closure in case that the valves are
not in the correct position.
NOTE: The valves MUST be put in 'Bushing normal operation' position (see Table 11), sealed by their metal
lids and the
¾" BSP connections closed with their own protective caps.
Missing this operation could be the cause of serious risks of damage of the bushing due to a lack of oil
circulation necessary for the internal cooling of the active part of grading capacitor.
7
Transformer turret arrangement and oil parameters
This chapter provides guidelines to the Transformer Manufacturer concerning the turret design and preparation
of the turret oil processing procedure. Turret design and oil processing procedure are under the responsibility of
the Transformer Manufacturer and the concepts illustrated in this part are not mandatory.
Required is, in any case, the achievement of the parameters for the oil inside the pressboard barriers and the
turret, listed in Table 13.
The turret shall be designed to withstand the vacuum and it has to be provided with adequate valves to allow
the proper bi-directional oil recirculation inside the barrier system. To perform this operation, it is suggested that
a suitable DN 25 pipe will be welded on the top flange manhole. The length of this pipe should be sufficient to
allow the injection of treated and filtered oil inside the pressboard barriers (see Figure 12).
A
DN 25
Oil sampling
internal pipe
valve
Example of turret manhole with filtering pipe
Example of internal DN 25 filtering pipe
Figure 12 – Example of turret manhole with internal DN 25 filtering pipe
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