Bushing Winder

Bushing winders - or: winding machines for condenser bushings - are used to wind insulating bodies for RIP or OIP condenser bushings from kraft or crepe paper and aluminum foil.

We design and manufacture the bushing winding machines according to your requirements for different lead-through lengths and with different levels of automation.

The challenge

High-voltage bushings are an important component of the energy infrastructure. Particularly against the background of larger transmission distances and higher voltages, the demands on the bushings are increasing. The voltage range for transformer bushings is now up to 1100 kV.

Capacitor controlled high voltage and high current bushings are the product of a sophisticated design and manufacturing process. There are several types of high voltage feedthroughs where aluminum foil and kraft paper or crepe paper must be precisely wrapped.

High-voltage bushings are an important component of the energy infrastructure. Particularly against the background of larger transmission distances and higher voltages, the demands on the bushings are increasing. The voltage range for transformer bushings is now up to 1100 kV.

Es gibt verschiedene Ausführungen von Hochspannungsdurchführungen, bei denen Aluminiumfolie und Kraftappier oder Krepppapier präzise gewickelt werden müssen.

Kondensatorgesteuerte Hochspannungs- und Hochstromdurchführungen sind das Produkt eines hochentwickelten Konstruktions- und Fertigungsprozesses

Today’s challenges in power transmission call for reliable, fail-safe bushings. Particularly with regard to the ever growing demand of High-Voltage Bushings of up to 1100 kV, new requirements relating to improved quality and enlarged physical dimensions have to be fulfilled. Our sophisticated winding technology, based on sound knowledge and decades of experience – combined with most modern computer aided engineering provides you with the answer to that call. Menzel already proved the case.

To improve the performance of paper insulated bushings, metallic foils can be inserted during the winding process. These act to stabilize the generated electrical fields, homogenising the internal energy using the effect of capacitance. This feature resulted in the condenser/capacitor bushing.

The condenser bushing is made by inserting very fine layers of metallic foil into the paper during the winding process. The inserted conductive foils produce a capacitive effect which dissipates the electrical energy more evenly throughout the insulated paper and reduces the electric field stress between the energised conductor and any earthed material.

Condenser bushings produce electric stress fields which are significantly less potent around the fixing flange than designs without foils and, when used in conjunction with resin impregnation, produce bushings which can be used at service voltages over one million with great success.

 

Solutions for electrical industry

Using our experience and high-precision winder technology, we are able to offer bushing winders for high-voltage feedthroughs up to a width of 14,000 mm. Our unwinders feature precise web guiding and tension controlled drive systems as well as integrated edge cut and edge strip winders. The system of controlled infrared preheating and heated rolls helps to reduce the residual moisture of the paper and thus also to minimize the drying effort/duration in the vacuum chamber. Die automatische Bohrvorrichtung mit Doppelbohrspitze garantiert sicheres Anbohren. We also offer the possibility to combine 2 machines, so that also extra large bushings can be produced.

 Length of bushing: max. 14.000mm
Winding speed: 2 – 30 m/min
Winding diameter of bushing: max. 900mm
Width of paper batch at unwinder: max. 5000mm
Diameter of paper batch at unwinder: max. 800mm
Material tension of paper: 50 – 500Nm
Weight of paper: 50 – 100g/m²
Weight of aluminium film: 15 – 40g/m²
Temperature of IR-heating device: up to 160°C, adjustable

High current bushing

Bushing-Wickler-Papier

High voltage bushing

High voltage and high current bushings

Functionality of capacitor controlled high voltage and high current bushings

All materials that carry an electric charge generate an electric field. When a current-carrying conductor is near a material at ground potential, it can build up very high field strengths, especially where the field lines are forced to curve sharply around the grounded material. The bushing controls the shape and strength of the field and reduces the electrical stresses in the insulating material.

Condenser bushings may seem simple, but they are the product of a sophisticated design and manufacturing process. Unlike solid bushings, a condenser bushing uses coaxial conductive layers inserted into the insulation at predetermined radial intervals; this design separates the center conductor from the bushing's outer insulator (housing).

The multiple conductive inserts form concentrically arranged and series-connected capacitive elements called "capacitors" or "condensers". Their purpose is to control the electric field around the center conductor (axially and radially stepped) so that the voltage is more evenly distributed across the surrounding insulation system of the bushing. The electric field is controlled to optimize the size, mass, and electrical performance characteristics of a bushing based on voltage class and other operational requirements.

Different designs of capacitor-controlled high-voltage and high-current bushings

  • RBP (Resin Bonded Paper) is a name for a bushing made of a resin-coated kraft paper
  • OIP (Oil Impregnated Paper) is a term used for bushings where plain kraft paper is used and the condenser core is impregnated with transformer grade mineral oil.
  • Printed OIP (Oil Impregated Paper) areas printed with conductive graphite ink on kraft paper that absorb voltage like a capacitor, and the capacitor core was impregnated with transformer grade mineral oil.
  • RIP (Resin Impregnated Paper), a technology is used in which a crepe-like paper is used in the capacitor core, which is wrapped with aluminum foils for voltage grading. After the paper core is wrapped to form the capacitor, it is inserted into a metal cylinder that is completely filled with epoxy resin under vacuum.
  • RIN (Resin Impregnated Nonwoven) is very similar to the RIP and RIS, except for the insulating material used to accommodate the aluminum foil stress gradients. The RIN condenser core is made of a nonwoven fabric instead of crepe paper or synthetic mesh to allow resin penetration at the lowest possible material moisture content and to form a fully encapsulated, void-free condenser body with virtually no partial discharge.
  • RIS (Resin Impregnated Synthetics) is very similar to the RIP, except for the insulating material, which is aluminum foil to accommodate the voltage gradients. The RIS capacitor core uses a synthetic mesh instead of the crepe paper to allow the resin to penetrate and form a fully encapsulated, void-free capacitor body with virtually no partial discharge.

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Do you need more information? We look forward to hearing from you!