Nomex® Electrical Insulation: Placing Tensile Strips in Oven
Thermal stability of electrical insulation paper can be evaluated after heat aging in a laboratory oven. The samples are cut into tensile strips and placed in a perforated Nomex® pouch for aging. Nomex® is used for the pouch for its high thermal stability and ability to be ultrasonically welded.
The sample pouch is placed on a stainless steel support rod. Clamps are then placed on each end to hold the rod in position in the oven. The preheated oven is temporarily switched to the OFF position to allow for sample insertion. Thermally rated gloves are worn to protect against incidental contact with the hot surfaces of the oven during sample insertion. After the door is closed, the oven is switched back to the ON position and the controller settings are verified. An aging cycle ranges from a few hours to a few years depending on the test. Once the cycle is completed the sample pouch is removed from the oven and placed on a table to cool. To avoid accidental burn injuries, a HOT sign is set in place to alert others while the samples cool to room temperature.