| a) Flat wire b) Conductor insulation c) Products for stack consolidation d1) Main wall insulation VPI mica tapes d2) Main wall insulation RR tape (Resin Rich) e) Finishing or sealing tapes f1) Conductive and semi-conductive tapes f2) Conductive or semi-conductive varnishe g) Bracing materials (spacers) h) Slot wedging materials |
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The quality of production and repair of electrical machines is very much determined by the quality of electrical insulation.
SIBEL Ltd. offers the high-quality insulation materials of the world leader in electrical insulation – the company VON ROLL – Switzerland.
The VPI system uses dry (4 ÷ 8% adhesive) insulating materials. In this system, the sections or the entire stator is inserted into an autoclave, subjected to vacuum, impregnation by injection with a resin under pressure and subsequent baking in the oven.
The quality of the VPI system, apart from used electrical insulating materials, is very much determined by the qualities of the impregnation resin and the proper course of the process.
The main advantages of a VPI insulation system are the following:
- Thermal insulation class - class F or - is usually determined by the impregnation resin.
- High insulation breakdown voltage - over 50 KV/mm.
- Low water absorption of the system.
- Small dielectric losses - due to evacuation and subsequent impregnation under pressure.
- Mica based insulation for high partial discharge resistance.
- Very good thermal conductivity.
Significant disadvantages of the system can be noted: high cost; expensive technological equipment; unfit for repair (in the presence of a damaged section, all sections of the stator must be removed).
Modern insulation materials that fulfill the specific requirements applicable to the VPI system:
Insulating Systems for Large Generators
Samicapor 374.04 – Mica tape for main wall insulation. Samicafilm 315.14 - Mica tape for conductor insulation. Isomica 326.02-01 – Mica tape for main overhangs insulation. Samicaflex 366.18 - Mica tape for main overhangs insulation class Н and С. Myosam 315.02 – Mica tape for ground insulation. Еpoflex 324.03 – External reinforcement tape for mechanical protection. CoronaShield P 8001 – Semi-conductive varnish for end corona protection. CoronaShield P 8003 – Conductive varnish for end corona protection. CoronaShield SC 217.02 – Semi-conductive tape for end corona protection. CoronaShield SC 215.51-03 – Conductive tape for end corona protection.
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