29.11.11 / KREMPEL´s POWERBOARD AK for power transformers: New product line satisfies the highest standards for electrical insulation materials used in the high-voltage (HV) sector

• Millions invested in the new POWERBOARD AK product line

• Optimum purity achieved with high-quality cellulose production based on an in- house inspection standard

• Tests of POWERBOARD AK according to customer specifications and approval procedures with virtually every well-known manufacturer of power transformers

• On-site service for complex applications and the versatile range of uses of POWERBOARD AK

• Unique adhesive variant for laminated board version/>
  
• KREMPEL – a TRANSFORM partner since 2010

 

 

 

Vaihingen / Enz, Germany  – With POWERBOARD AK the KREMPEL-GROUP has successfully extended its range of high-end electrical insulating materials for use in oil-insulated power transformers. Since 2011, this new product family has been approved by almost all the leading manufacturers of power transformers. The main features of our cellulose-based pressboard and laminated board are highest purity and flexibility. We accomplished this feat by investing millions in the Zwoenitz pressboard plant in Saxony.

 

The electrical insulation materials employed in the development and production of electrical machinery and systems are subject to exceptionally challenging requirements. An excellent reason for KREMPEL to process nothing but the finest-quality materials, using ultra-modern manufacturing processes. Its new POWERBOARD AK product line has enabled the company to bridge a gap in insulating materials. “In 2006 there was a worldwide shortage of insulation materials for power transformers”, reports Uwe Assmuth, one of the two Managing Directors of KREMPEL. “During this time, we were approached by manufacturers who already had a high opinion of our insulation materials from their application in distribution transformers. This gave us further impetus to implement our plans for expanding our portfolio.” Production of the POWERBOARD AK line began at the pressboard plant in Zwoenitz back in 2007. To date, the 15 million € production facility built here is the largest single investment in the history of the KREMPEL-GROUP.

 

New production facility made of stainless steel

An investment that the company made with its sight firmly focused on the product quality. “Purity, coupled with electrical and mechanical properties, is a decisive factor in the ability of electrical insulation materials to be used safely over a number of decades”, states Rudolf Mitterhammer, Area Sales Manager at KREMPEL. “Any impurity found at the high electrical field strengths inside a transformer coil can cause hazardous partial discharges, and these can ultimately cause the entire transformer to malfunction.” There were very cogent and compelling reasons behind the company’s decision, taken at its head office in Vaihingen / Enz in Southern Germany, to build a very special kind of plant indeed. The water-intensive production of POWERBOARD AK runs 24 hours a day, seven days a week – rust and mechanical wear would be inevitable in a conventional plant. This explains why KREMPEL's new production facility is built entirely from stainless steel, including the pipework system and the pumps.

 

Cellulose from the North, water from the mountains

The way this plant was built, coupled with an elaborate manufacturing process and the meticulous choice of raw materials, is what creates the high quality of the POWERBOARD AK. Pressboard is hot-pressed from 100% pure unbleached sulphate cellulose that is obtained from northern conifers.  Due to the low ambient temperatures, these trees grow very slowly, so they develop longer fibres than trees at southern latitudes. The longer these cellulose fibres, the higher the mechanical strength of the fibre fleece – which forms the basis of all pressboard products in the POWERBOARD AK line. KREMPEL obtaines the water it needs to process this cellulose from a catchment basin situated on the company ground. This basin collects mountain water from the surrounding Erzgebirge mountain range. This water only requires a simple filtration process. There is no need for additional chemical processing which might otherwise found in the water-cellulose mixture. The company’s in-house purity directive is assured by its own inspection specification, something that is still unique to KREMPEL. Regular material inspections ensure a consistently high standard of quality.

 

Tests according to customer specification and expertise for users

The need for company-specific inspection standards is something this electrical insulation materials specialist has learned from its own working practices. Which explains why KREMPEL has a laboratory with a high-voltage (HV) testing station. Here, the company is able to run tests in accordance with customer specification, and can do so quickly and professionally. The altogether positive results explain why the POWERBOARD AK line has now been approved by virtually every renowned transformer manufacturer. Just like all of KREMPEL’s customers, they also stand to gain from the company’s experience and expertise:  “We interpret ‘backing up your own product’ to mean supporting customers with their application”, reports Tobias Zaiser, Head of the Electrical Insulations Division, “if for example, our pressboards are to be rolled up to form insulating cylinders, our specialists go out on site when required to show how best to accomplish this outcome.” 

 

 

Unique type of adhesive for POWERBOARD AK laminated board

It is the flexibility of the POWERBOARD AK product family that makes it so eminently suitable for a versatile range of applications in power transformers. Strips, spacers and pads – essentially all components needed in the manufacture of windings - can be shaped using stamping, boring, milling and sawing processes. KREMPEL employs a multiple-layer laminate bonding process to make the high-quality laminated pressboard using POWERBOARD AK. Here, transformer manufacturers can choose between conventional casein and polyester resin adhesives, or they can opt for the phenol resin adhesive that, to date, only KREMPEL employs in this application. The last of these options combines the electrical advantages of casein with the mechanical benefits of polyester resin in a single adhesive.

 

KREMPEL – a TRANSFORM partner since 2010

The latest product line from KREMPEL attracted very high levels of interest at the TRANSFORM 2011 in Singapore. With 450 guests from 46 countries, the conference for Transformer Applications in April set a new record for visitor numbers. Since 2010, KREMPEL has also been a TRANSFORM partner and now stands alongside the premium providers Maschinenfabrik Reinhausen, Omicron, HSP, Nynas, PFISTERER, Röchling Engineering Plastics, ThyssenKrupp Electrical Steel, Essex and GEA Heat Exchangers. Under the event’s banner heading of ‘Sustainable Transformer Technologies’, users, manufacturers and suppliers from the transformer industry was offered a rich and diverse range of topics comprising 26 technical lectures, including one by the KREMPEL GROUP on the behavioural characteristics of pressboard in relation to the absorption and dissipation of humidity.