Electrically conductive materials from Krempel are used as corona protection in high-voltage applications such as generators, transformers, motors, instrument transformers and cables. The electrically conductive tapes are used for internal and external corona protection. Semi-conducting tapes are used for potential control and terminal corona protection. The corona protection materials prevent partial discharge, support the insulation system, increase operational safety and contribute to a longer service life.
Electrically conductive materials for corona protection
- Conductive and semi-conductive tapes/conductive woven and non-woven fabrics for inner, outer and terminal corona shielding
- Conductive plastic sheets as slot fillers in the stator
- Conductive paints for corona shielding and terminal corona shielding on coils and rods in stator windings
- Conductive epoxy resin paste for smoothing the surface on the narrow ends of the Roebel bars
Conductive and semi-conductive tapes
Conductive woven fabrics and conductive non-woven fabrics
To produce our conductive and semi-conductive tapes – also known as conductive woven fabrics and conductive non-woven fabrics – we use polyester woven and non-woven fabrics, glass woven and non-woven fabrics and hybrid woven fabrics. These are impregnated with electrically conductive binding agents on special systems.
Various surface resistances of between 50 and 20,000 Ohm are available in our standard range. We also offer customer-specific resistances to meet special requirements.
The basis of our semi-conductive corona shielding tapes
Our AKASIC semi-conductive corona shielding tapes are based on hybrid woven fabrics with polyester fibres in the warp direction and glass fibres in the weft direction. They are used as potential control in medium and high-voltage machinery (≥ 6 kV). When used in this way, the semi-conductive tapes prevent partial discharges and contribute to the longer service life of the high-voltage insulation.
The basis of our conductive corona shielding materials
Polyester non-woven fabrics with additional polyester fibres in the machine running direction for reinforcement. This leads to increased mechanical strength in the longitudinal or winding direction. The polyester fibres can be made to shrink through the application of heat.
Polyester nob-woven fabrics with statistical longitudinal fibre orientation in the machine running direction. This fibre orientation leads to increased strength in the longitudinal direction compared to the transverse direction
Polyester non-woven fabrics with a particularly high elasticity in the transverse direction.
Polyester non-woven fabrics with statistical random fibre orientation. This fibre orientation has the same strength in all directions.
Woven or non-woven fabrics made from glass fibres, for applications in temperature class H (180°C).
Polyester fibres in the warp direction and glass fibres in the weft direction. The polyester fibres in the warp direction can be made to shrink through the application of heat.
Rigid, electrically conductive plastic sheets
Our rigid, electrically conductive sheets are used in high-voltage electrical machinery as slot fillers in the stator. They guarantee reliable electrical contact between the electrically conductive corona shielding on the winding rods and the slot wall of the stator laminated core. The plastic sheets also ensure the optimal balancing of slot tolerances.
We also offer our side ripple springs and top ripple springs as slot fillers.
Our conductive paints are used in rotating high-voltage machinery in order to prevent partial discharge, thereby protecting the high-voltage insulation.
Conductive epoxy resin pastes
Our "KREMkitt R" conductive epoxy resin pastes are used to smoothen the surface on the narrow ends of the Roebel bars in high-voltage machinery.
Applications of our corona protection materials
In large transformers and inverters, the iron cores are wound in electrically conductive tape in order to prevent partial discharge.
High-voltage motors and generators
Electrically conductive materials are used in high-voltage generators (hydropower and turbo generators), high-voltage motors and rotating high-voltage machinery as corona shielding for the high-voltage insulation. This protection prevents partial discharge, supports the insulation system, increases operational safety and contributes to a longer service life.
Electrically conductive materials are used in instrument transformers for shielding and potential grading. For special applications, conductive non-woven fabrics are also provided with a self-adhesive layer on one side for more efficient taping and to stop the tape from slipping, and also to prevent casting resins from getting into the high-voltage winding.
Our electrically conductive materials based on polyester stretch non-woven materials are used in high-voltage cables for potential grading. The stretch non-woven materials prevent air pockets, withstand the bending strains when the cables are being laid, and can be temporarily exposed to high temperatures without any changes to their properties.