MIL-I-24718

Abstract

This specification covers solventless insulating resins of various compositions and classes for treating and impregnating electrical equipment by the vacuum-pressure-impregnation (VPI) process. <br>Insulating resins shall be provided in the following compositions and classes, as specified (see <a>6.2</a>). <br>Solventless impregnating resins shall be identified by chemical family and rheological properties, as defined by the individual specification sheets. The composition description shall identify all primary reactants in the resin formulation (for example, epoxy-Lewis acid, polyester diallyl phthalate, and so forth) and the rheology required for its end-use application (for example, thixotropic, slightly thixotropic, low viscosity, and so forth). Each specification sheet describes a unique composition. <br>Each composition shall be of one of the following class designations. Class is an indication of the thermal endurance (see <a>4.6.15.1</a>). Glass is determined from the temperature index rating in degrees Celsius (&#176;C) at 20,000 hours. </span><pre> <u>Thermal class</u> <u>Temperature index range</u> Class 105 105 up to but less than 130 Class 130 130 up to but less than 155 Class 155 155 up to but less than 180 Class 180 180 up to but less than 200 Class 200 200 up to but less than 220</pre> <br> <strong>Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 55Z3, Department of the Navy, Washington, DC 20362-5101 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.</strong> <br><b><u>Intended Use:</u></b> The insulating products covered by this specification are intended for impregnation and complete void fill of all types of electrical coils and windings. They should be rated for continuous operation at the maximum operating temperature specified for each class. Products may also be used at temperatures lower than the thermal class. Products covered by this specification are intended for use in the VPI process. The primary purpose of the impregnant is to protect the coils from the operating environment. Questions regarding the effect of compounds procured with this specification on the health of personnel involved in its utilization should be referred by the contracting activity to the Naval Medical Command (NAVMEDCOM). NAVMEDCOM will act as an advisor to the contracting activity when requested (see <a>3.3.4</a>). <br>