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NEW COIL ENCAPSULATION WITH RYNITE PET BOOSTS MOTOR'S PROTECTION AGAINST HEAT AND MOISTURE
Hansen Corporation has improved the heat and moisture resistance of its Class F Synchron; synchronous timing motors by encapsulating their stator coils with DuPont; Rynite PET thermoplastic polyester resin. The motors are chiefly used to control and operate vents and valves in heating, ventilation and air conditioning systems. They are the first timing motors rated for Class F (155° C) applications under the UL 1446 standard that deliver the benefits of thermoplastic encapsulation technology to motor buyers, according to Hansen. "Polymer encapsulation provides more resistance to heat, moisture and other operational stresses than conventional tape and varnish technology," says John Muncy, manager of manufacturing engineering for Hansen. "Tape and varnish can crack or separate, but encapsulation with Rynite assures a hermetic seal," he adds. The encapsulated coils also perform better in high-potential tests, according to Muncy. Encapsulation reduces manufacturing costs and improves quality, too. "We can better maintain tolerances in stacked coils due to the more uniform coil heights, and that aids manufacturing efficiency. Encapsulation also reduced in-house failure rates," Muncy explains. Hansen encapsulates its stator coils in a single step using efficient injection molding machinery. The coil, which is wound on a bobbin also made of Rynite PET, is placed in the mold and overmolded with Rynite PET. The encapsulated coils come out of the mold ready for motor assembly with no secondary finishing steps required. The company was able to transition quickly from tape to encapsulation by using a pre-approved, pre-tested DuPont electrical insulation system for UL 1446 Class F applications. The system specifies Rynite 415HP for encapsulation and Rynite FR530 as ground insulation, i.e., the coil form. "Since we had no approval hurdles to overcome, the EIS saved a great deal of time and expense," Muncy reports. The pre-approved EIS used by Hansen is one of more than 400 such systems available to DuPont customers. The systems are recognized by Underwriters Laboratories and many global authorities. For more information, visit www.e-insulationsys.com on the Web. Hansen also had the benefit of encapsulation experience gained with its Class A (105° C) synchronous motors using a different polymer, DuPont; Zytel nylon resin. "We've been encapsulating coil windings for several years now, so this is proven technology," says Muncy.
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