High-heat thermoplastics are poised to replace thermosets in demanding electrical applications, such as molded case circuit breakers (MCCBs) used in heavy duty circuit breakers.
Royal DSM says that new research with the Electrical Research & Development Association (ERDA), a research group in India, shows that arc chutes injection molded in thermoplastics such as polyamide 4,6 could withstand the thermomechanical and electrical stresses developed during a short-circuit in MCCBs with breaking capacities up to 25 kA. Polyamide 4,6 was said to provide increased safety margins over thermosets, even in parts with lower wall thicknesses.
The primary function of the arc chute is to provide final cooling of the arc, to help avoid an arc re-strike, and preserve the integrity of the contacts to increase the service life of the MCCB. Arc chutes have been made in thermoset composites (DMC/BMC).
Materials in the test included Akulon PA6,6, which has a melting point of 255°C and a maximum continuous-use temperature of 180°C; and Stanyl PA4,6, which has a melting point of 295°C and a maximum continuous-use temperature of 230°C.
Jiangsu Phono Electrical Co. Ltd. in China is commercializing the concept.