Today’s complex electrical systems demand greater diligence in verifying that individual insulation materials can and will perform safely in shared environments. UL offers comprehensive testing and certification services available to the insulation systems industry.

UL is unique in the way it evaluates and certifies insulation systems. In addition to assessing insulation materials as individual components, we also evaluate the applicable system as a whole. This allows us to determine if components interact in unsafe ways or react chemically at certain maximum temperatures, which may cause product failure or other hazards to occur.

Thermal stress is the primary factor affecting the service life of insulating materials in electrical equipment. UL’s systemic and holistic approach to insulation systems certification increases confidence in the whole system, and provides equipment manufacturers with additional peace of mind that the insulation system is safer for long-term use.

UL constantly expands our portfolio of insulation systems certification services to better serve component manufacturers and OEMs, allowing our customers to keep pace with the new technological developments in their respective industries.

We offer motorette testing and assembly. Motorettes, also known as general-purpose models, are nonfunctional test samples designed specifically for test purposes. A motorette represents all of the major elements of a functional product, such as the ground/interwinding insulation and winding wires. Nonfunctional test samples offer many advantages over the testing of functional samples, such as the ability to test multiple alternative insulation materials and wire types simultaneously. We test both functional and nonfunctional samples in accordance with UL 1446 and IEC 61857-21.

In addition to evaluating these products for certain common physical properties, UL evaluates these products for specific end-use applications, such as enclosures for electrical equipment, motor fuel dispensing devices, etc., when the governing standard has requirements that differ from ANSI/UL 157. We also test to IEC 60085 Electrical Insulation – Thermal Classification and ANSI/UL 1446, the Standard for Safety of Systems of Insulating Materials – General, for the U.S. market.

Other standards that may be used, where appropriate include:

  • ANSI/IEEE C57.12.56-1986, IEEE Standard Test Procedure for Thermal Evaluation of Insulation Systems for Ventilated Dry-Type Power and Distribution Transformers
  • ANSI/IEEE C57.12.60-1998, Guide for Test Procedures for Thermal Evaluation of Insulation Systems for Solid-Cast and Resin-Encapsulated Power and Distribution Transformers
  • ANSI/IEEE 275-1992, Recommended Practice for Thermal Evaluation of Insulation Systems for Alternating-Current Electric Machinery Employing Form-Wound Preinsulated Stator Coils for Machines Rated 6900 V and Below

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