At the CWIEME 2025 exhibition in Berlin, Germany, WACKER showcased a new electrically conductive silicone rubber designed for power plant generators. The event, focusing on coil winding, insulation, and electrical manufacturing, took place from June 3 to 5.
WACKER’s new product, ELASTOSIL® N 9189, is made for sealing and bonding in generators. It helps prevent damage during operation. The company also highlighted ELASTOSIL® N 2076, an electrically insulating silicone rubber that protects electric coils from environmental harm.
ELASTOSIL® N 9189 is a non-sag silicone that flows when pressure is applied. It is a one-component RTV-1 silicone rubber that cures at room temperature when exposed to humidity. During curing, it only releases alcohol. The cured rubber has a medium Shore hardness and can handle temperatures up to 230 °C for long periods.
This silicone sticks well to many materials used in electrical engineering. It does not need special surface treatments. A key feature is its electrical conductivity. The cured rubber has a volume resistivity of 10 ohm-centimeters. This means it conducts electricity better than seawater and similar to a 10-percent salt solution. Because of this, it can dissipate electrical charges effectively from surfaces.
ELASTOSIL® N 9189 is ideal for use in large power plant generators. These generators have stator windings made from copper bars called Roebel bars or composite conductors. These bars fit into slots in the stator laminations. High electrical fields occur at the slot ends during use. This can cause corona discharges. Without protection, these discharges may damage the copper bars’ insulation over time. Using ELASTOSIL® N 9189 to bond the copper bars at the slot exits improves electrical field distribution. This protects the stator from faults.
The new silicone is tin-free and releases only alcohol when curing. This makes it safer and easier to work with, especially regarding health and safety. ELASTOSIL® N 9189 is also better than its predecessor, ELASTOSIL® N 189, in conductivity and mechanical strength. WACKER plans to replace the older product with this new grade.
Another product presented was ELASTOSIL® N 2076, which is self-leveling and flame-retardant. Like ELASTOSIL® N 9189, it is a one-component RTV-1 silicone that cures at room temperature and releases only alcohol during curing.
ELASTOSIL® N 2076 has self-leveling properties. It is designed as a coating for electric coils and can be applied by dipping. This is useful for coating choke coils, transformer coils, and small motor end windings. The cured coating resists weather, UV light, and heat. It is electrically insulating and protects coils from moisture, dirt, and deposits.
ELASTOSIL® N 2076 is also flame-retardant. It meets the European fire safety standard EN 45545-2, which applies to rail vehicles.
