This standard applies to direct heating step type positive temperature coefficient thermistors, which is equivalent to IEC 60738-1:1998 "Direct heating step type positive temperature coefficient thermistors - Part 1: General specification". This standard is a revision of GB/T 7153-1987 "General Specification for Directly Heated Step Type Positive Temperature Coefficient Thermistors (for Certification)". The main difference between this standard and GB/T 7153-1987 is the addition of terminology, testing methods, and conditions related to directly heated step type positive temperature coefficient thermistors for current limiting, surge, and heating purposes, and the provision of terminology, testing methods, and conditions for current limiting, surge, and heating purposes List of Fixed Sample Size Qualification Approval Tests for Directly Heated Stepped Positive Temperature Coefficient Thermistors for Heating and Temperature Sensitive Use. The quality evaluation level has been changed from E to EZ, and the test method for surface mounted Directly Heated Stepped Positive Temperature Coefficient Thermistors has been supplemented
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