Ready to Generate - Wacker Chemie AG

Ready to Generate

Stucture of a Hollow-Core Insulator

Typical Application: Instrument Transformer

Switzerland is also home to Pfiffner Messwandler AG, in Hirschthal. This mid-sized company is a reputable maker of voltage and current converters for all voltage levels used in power transmission and distribution. These devices – small, specialty transformers – are capable of converting high voltages or currents to a measurable level so that they can be automatically further processed by electronic control devices.

This is necessary for two reasons. First, every power producer, every grid operator and every energy provider wants to know exactly how much electrical energy has been transported – even if it is only for billing purposes. The transformers employed for this must meet high accuracy specifications. Second, transformers are essential for protecting the grids. They are designed to detect any over-voltages or short-circuit currents, and the evaluation electronics are programmed to issue a signal to shut down the affected grid section as necessary. Instrument transformers are therefore vital elements of power transmission and distribution, and hundreds of thousands of them are used around the world – they can be found in the terminals of every cable, from power plants through to substations.

“We are convinced that silicone composite hollow-core insulators will become the standard for transformer external insulation.”

Fritz Hunziker Owner of Pfiffner Messwandler AG

Instrument transformers for high-voltage equipment are always custom-made. “Our expertise lies in correctly dimensioning the transformers for the intended application and in making them so that they will do their job totally reliably and without any maintenance for about forty years,” says Fritz Hunziker, owner of Pfiffner Messwandler AG. “We are convinced that silicone composite hollow-core insulators will become the standard for transformers' external insulation. We already use composite hollow-core insulators in half of our high-voltage equipment. Their practical benefits are so huge that our customers are increasingly ordering transformers with composite hollow-core insulators, even though they can be more expensive.”

Silicone Elastomers

Silicone elastomers are rubber-elastic solids derived from polyorganosiloxanes. They are made by the curing of silicone rubber, a process in which the polymer chains of the organosilicon macromolecules are chemically crosslinked to each other. Silicone elastomers do not absorb water and have a highly hydrophobic (water-repellent) surface. They are flame-resistant, dampen mechanical vibrations and are very good electrical insulators. Silicone elastomers are typified by excellent resistance to a wide range of physical and chemical stresses. For instance, their chemical, physical and technical properties remain constant over the range -45 to 180 °C. They also exhibit extraordinary aging resistance: withstanding permanent thermal, mechanical and electrical loads and continuous exposure to oxygen, ozone and UV radiation – without showing any change in their dielectric characteristics. Owing to this property set, silicone elastomers are ideal insulators for power transmission and distribution. They make a great contribution to the high operational reliability of outdoor electrical equipment.

Demand for instrument transformers and other electrical operating equipment is growing as power grids around the world are being expanded. And with it, demand for composite hollow-core insulators. Low-pressure diecasting has a proven manufacturing track record, the machines are available and, in POWERSIL® XLR® 630, WACKER has a silicone which is tailored precisely to both the process and the machines. WACKER developers are currently working on further developing low-viscosity liquid silicones for even faster processing, with a view to lowering production costs for silicone composite hollow-core insulators even further.