scope:

This specification covers the general requirements for established reliability, . insulated, fixed resistors having a composition resistance element consisting of a mixture of carbon, insulating material, and suitable binders, either molded together or applied as a thin layer of conducting material on an insulated form. Resistors covered by this specification shall have failure rates ranging from 1.0 percent to 0. 001 percent per 1,000 hours (see 1.2. l. 5) at 50 percent full-load operation at an ambient temperature of 70" C (see table I). These failure rates are established at 60 percent confidence level on the basis of life tests. The failure-rate, identified by the appropriate symbol, is referred to operation at rated temperature and at a voltage equivalent to 50 percent of rated wattage (with a permissible resistance change of i l 5 percent).