Interpretation of the standards and rules for domestic tubular electric heating elements:
In view of the increasingly developing technology and market demand, the state has re issued the new standard JB / t4088-2012 for domestic tubular electric heating elements to replace the old standard JB / t4088-1999. Subsequently, CQC updated the corresponding certification rules according to the new version of the standard. Interpretation of standards and rules revision, adjustment and addition of the old and new versions of standards and certification rules are given in detail as follows:
(1) changes in the scope of application: the requirements for single tube in the original standard are rated voltage no more than 440V and rated power no more than 4000W, while the requirements in the new standard are modified as rated voltage no more than 480v and rated power no more than 6000W, The contents of components not suitable for industrial use are added. In fact, the new standard defines the scope of certification, and expands the voltage and power range of single tube components according to the current market demand. In the corresponding new version of certification rules, the scope of certification is also specified, and the part of applying for certification by combining the components that meet the requirements of the new version of standard is also specified. The scope of application is the safety certification of combined heating components (hereinafter referred to as components) which meet the above requirements and are composed of multiple (single tube) tubular heating elements in series and parallel, The total power of the module does not exceed 36kw. That is to say, if the enterprise needs to apply for components, if the maximum power of single tube components is 6000W, the maximum number of components can be used for series parallel combination.
(2) Addition, deletion and update of reference standards: the corresponding reference standards are updated in the new version of the standard, and the reference standards of gb17196-1997 are added. This additional standard is mainly aimed at the plug-in terminals on some electric heating elements, and the plug-in terminals shall meet the size requirements of the standard. Therefore, enterprises that produce such plug-in terminals should pay attention to the requirements of corresponding standards when purchasing or manufacturing.
(3) Modification and addition of terms and definitions: the new standard redefines the tubular electric heating elements for daily use, and clarifies the types of products applicable to the standard. The definitions of "normal operation", "wet condition", "dry burning", "equivalent resistance" and "safe special voltage" are added, and the conditions in the definition of "damage" are clarified. In this way, on the one hand, it not only makes the enterprise more clear when designing and understanding the products, but also makes the laboratory understand the standard more clearly, which is conducive to the test. In the old standard, the hot water test was carried out according to the requirements of GB / t2423.3-1993, while in this new standard, the definition of corresponding moisture conditions and subsequent tests are directly written into the standard.
(4) Changes in product classification: according to the actual situation of products on the market and the emergence of some new products, the new standard has re classified and refined the classification of products. In the new version of the certification rules, the division of certification units is also modified according to the new version of standards and the characteristics of products on the market, as well as from the perspective of facilitating enterprises. For example, when applying for the old version of the standards and rules, the materials, structure and life of the products are consistent, and they need to be applied separately only because of different voltages. However, the new standards can be placed in a certification unit. In addition, in the new version of the certification rules, there are also clear provisions on how to send samples for series applications: the products with the largest surface load are the main inspection samples, the products with the largest single tube power are used as the covering samples, and the products of any specification are selected as the covering samples. If it is a component application, the sample delivery should be determined according to the actual situation of the sample.
(5) Modification and addition of product technical conditions: first of all, the new standard reduces the restrictions on the normal working conditions of components; secondly, the leakage current limit is changed from the original 0.5mA to 0.75ma; thirdly, the electrical strength test voltage is modified from the original unified value to different test voltages corresponding to different rated voltages of components; fourthly, the requirement of limit value of harmful substances is added; fifth, the limit value of harmful substances is added, Some dimensional requirements of products have been changed; finally, according to the classification of components in the new standard, the tube temperature test requirements for some components are added, and the limits of various materials in Appendix C are provided. In addition, the appendix of the new version of certification rules also requires the factory to declare all kinds of materials and information clearly in the application. It should be said that these amendments reflect the constant changes of standards with the changes of market and international situation. For example, the limit requirement of hazardous substances is to consider the current more popular environmental pollution requirements, and the electrical strength test is more scientific