Control and visual input inspection: Tan-δ and capacitance check fastening fixation ring “A” to loosen disassembly. Red epoxy insulator.
Disassembly of the fastening-fixing ring “A” revealed strongly adhering encrusted carbon dust contamination between insulator and sealing O-ring penetrated from the outside. The O-ring seals are largely destroyed.
Further disassembly of the fastening fixation ring, the sealing O-ring and the epoxy insulator, as visible in the left edge of the picture, reveals increased dirt dust.
Interior view of the disassembled epoxy insulator: Heavy contamination and crystallized insulating gap filling visible from both sides. After cleaning and inspection, the insulator proves to be reusable.
Detail of the inner surface of the feedthrough control with penetrated contamination.
In this feedthrough, the control system had to be replaced; except for seals, all other parts were recyclable. The feedthrough proved to be absolutely as good as new after retrofit.
Repair & retrofit order : 6 generator bushings 30kV
Porcelain insulators at delivery and survey: flashover and arc traces
- Electrical testing & PD measurement
- Condition analysis and report for the customer for retrofit
- Offer with schedule / control and customer order
- Disassembly, cleaning and revision
- Replacement of defective insulators and seals
- Reassembly
- Electrical and leakage final test and inspection
- Packing & shipping
Porcelain insulators replaced by newly manufactured insulators during retrofit: Final electrical test. Operating frequency test voltage 50Hz -1 minute, with partial discharge control and measurement of capacitance and, Tan-δ of performance after successful retrofit.