In inverter driven motors, excessive surges and voltage peaks during speed variation, creates corona discharge in the stator windings, which induce extra thermal stress on the insulation, causing excessive thermal ageing there by weakening and even decomposing of the insulation, leading to premature failure of motors. Corona induced failure is a typical phenomenon. Mica based products are used in certain application where corona resistance is required. Mica is naturally occurring and is available easily. But it has its own inherent weakness. It has poor flexibility and large area and as such, the space required is more for any mica based application. This result by increasing the size of the motor, making it unusable where space constraints are there. Moreover it has poor adhesion to most of theresins. Improved dielectric materials having resistance to corona discharge-induced deterioration would therefore be highly necessary. M/s. Dupont has been manufacturing corona resistant Wire enamel under the brand name “Voltatex”.
Corona Resistant Winding Wires are used in Inverter drives & Stator Windings.
0.63 mm to 3 mm
Basecoat of Corona resistant wire enamel class 200°C
Top coat of Polyamide-imide (PAI) class 200°C +