Instrument transformer components

Description
Outer casing and core jacket in Rynite® PET thermoplastic polyester resin for toroidal 600 V current transformers used to monitor electrical flow. The core jacket goes between the transformer's ferrite core and windings to prevent damage to the magnet wire by the core's sharp edges. The outer casing insulates the transformer from a primary conductor, which passes through the hole in its center. Consisting of two parts joined with hot-melt adhesive, the casing also protects against mechanical damage and the entry of foreign matter.

Benefits
Higher temperature rating. Thanks to use of Rynite® and other materials making up an insulation system recognized by UL for Class B, 130°C service, Square D can supply these transformers for a broader range of applications. Competitive instrument transformers using less heat-resistant plastics such as PPO/polystyrene alloy are rated for only 105°C.

Savings in cost, time. Use of a DuPont preapproved total package system reduced the cost and time required for UL recognition, a key market need, according to Victor Kennedy, Materials/Quality Assurance Manager at Square D's Clearwater operation.

Improved stress crack resistance. Test data show that components in Rynite® outperform PPO/polystyrene parts used in competitive units.

Materials Used
Rynite® PET provides the required combination of high-temperature resistance, listing in a preapproved Class B UL 1446 Class B (130°C) system, UL V-0 performance, stress crack resistance, strength, stiffness and high productivity in injection molding.

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