In UL standard 1446, Electrical Insulation System (EIS)is defined as: “an intimate combination of insulating materials used in electrical equipment. For example, the combination of a coil form, separators, magnet-wire coating, varnish, lead-wire insulators, and outer wrapping of relay coil”

EIS (Electrical Insulation System) Testing
Qualification of an insulation system to either UL 1446 or IEC standard requires testing of complete, assembled insulation systems. Electrical equipment manufactures are faced therefore with testing the actual equipment substituting a motorette or transformerette that represent their system; or using a recognized EIS through a material supplier, Because final recognition of a system by UL requires that the system go through 5000 hr of heat aging at the lowest of the three or four temperatures the system is tested at, many manufacturers choose the pre-approved system option.

The EIS test is composed of two test procedures, One qualifies the major components of the insulating system by constructing the Test Rigs (Motorette) for testing .The major components include ground insulation, magnet wire, intertwining insulation, and varnishes, The dip varnish can be considered a minor component if the motorette or transformerette did not use a varnish. The other procedure is called the “sealed-tube testing” which is for the minor components of the insulating system such as the tapes, lead wires, sleeving material and the dip varnishes.

The Allowable Magnet Wire Substitutions

Use the following for MW substitutions into established EIS

• * means this type of magnet wire has a PA = Polyamide overcoat or topcoat as a dry lubricant. (Example, Nylon is a Du Pont Trade Mark for PA)

• All types of magnet wire listed above refer to Copper. In some specific cases where the letter “A” is listed = Aluminum wire only.