Electrical Insulation System / EIS
(UL1446, IEC60085)

Motors, transformers, relays, and solenoids consist of electromagnets, and magnetic wire that generates electromagnetic induction as well as other components  such as bobbins, tape, film, lead wire, tubes, and varnish. This assembly of the components used in electrical equipment is called insulation system. Generally, polymer material generates a volatile constituent, such as decomposition gas, as the temperature increases. Such volatile constituent may cause deterioration of components including magnet wire. Progress of deterioration can result in loss of insulation performance and ultimately in loss of product function. In order to determine the effect of such volatile constituents, it is important to evaluate these components as an insulation system rather than as individual units.

When establishing a brand-new insulation system, magnet wire, and polymeric materials (including films, as well as bobbin tapes) necessary for the product are incorporated as a single test sample. This incorporated test sample is called motorette (or GPM: General Purpose Model). Deterioration condition is examined by repeatedly conducting the dielectric voltage withstand test under specified conditions, once the sample has been conditioned by specified thermal aging. Thermal Index (TI) of the insulation system shall be determined by 5000 hours or more of aging at the minimum temperature as stated in UL746B and IEC60216 standards. For evaluation, the thermal index is determined as compared to a control system. In Japan, only Chemitox has this control system for evaluating insulation systems. The control system needs to be updated every five years, and ours has recently been updated on 8/30. Because we have our control system, our customers can conduct aging tests, not at the same time as the control system, unlike UL746B, and acquire a temperature class. Also, our control system has wire diameters of ɸ1.0 mm and ɸ0.5 mm, which are the maximum and minimum defined by the standard. This allows our customers to choose from ɸ1.0 mm and ɸ0.5 mm as the wire diameter for their motorette, since the control system and the motorette are required to have the same wire diameter.