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The heat resistant evaluation and grade for insulation material
Author:quanda  Source:  10/24/2013

Subject Matter and Scope 

   This standard specifies the electrical insulation of the heat resistance of the product classification, defines the principles and tasks of the heat resistance of the assessment and grading. 

   This standard applies to electrical insulation and heat resistance of the product classification also apply insulating material applied under certain specific occasions, a simple combination of heat resistance and insulation grading structure. 


2 Reference Standard 

   GB 11026.1 determine the heat resistance of electrical insulating materials Guide Part I: formulation of thermal aging test methods and evaluation of test results overall procedure 


3 Subjects 

3.1 Thermal class 

   Electrical insulation products used by a variety of factors (such as temperature, electrical and mechanical stress, vibration, harmful gases, chemicals, moisture, dust and radiation, etc.) influence, and the temperature is usually insulating materials and insulation aging factors play a dominant role. So there are a practical, is recognized as a world heat resistance classification method, which is heat-resistant electrical insulation is divided into several heat levels, various heat levels and the corresponding temperature values are as follows: 

Heat grade temperature, ℃ 

Y 90 

A 105 

E 120 

B 130 

F 155 

H 180 




   Temperature exceeds 250 ℃, 25 ℃ press intervals corresponding setting heat levels. 

   Letters can not heat levels, but must comply with the correspondence. Under special conditions of use, and equipment with special requirements (as described in Section 3.1.5 above), the above classification method may not be applicable, you may want to use other triage methods. 

   Indicated on the electrical products in heat levels, usually indicates that the products meet the highest temperature expected to withstand the use of at rated load and other conditions specified. Therefore, electrical products, the highest temperature insulating premises should not be lower than the temperature of extreme heat levels of the product corresponding to the temperature (otherwise see Section 3.1.2). 

   Due customary, regardless of the current insulation materials, insulation and electrical products generally use the "heat rating" of the term. However, the future trend is that the insulating material is recommended "temperature index" and "relative temperature index" of these two terms; insulation is recommended for "identification mark" of the term; insulation structure "identification mark" and designed only the occurrence of certain products contact; while electrical products retains a "heat rating" this term. 

3.1.1 Operating Conditions 

   Experience has shown that: standard if electrical products (such as rotary motors, transformers, etc.) is the temperature listed in Article 3.1 basis with due consideration of factors specific to the formulation of the product, then, according to this standard design and manufacture of electrical products under normal operating conditions and has a satisfactory and economical use period. 

3.1.2 insulation insulating material 

   Indicate a level of electrical products for a heat-resistant, insulating structure by no means the product of an insulating material each have the same temperature limits. 

   Temperature extremes and temperature limits for each insulation material which may not be directly related to the insulation structure. In the insulation, the temperature limit of insulating materials may be due to other components of the material subject to protection and improved, it may be due to incompatibility between the material leaving the insulation temperature limits below the temperature limit of the various components of the material. All of these issues should be studied by functional tests. 

3.1.3 Temperature and Temperature Rise 

   Temperature listed in this standard refers to the highest temperature electrical insulation products to bear, not electrical products allowable temperature rise. 

   Electrical equipment standards specified temperature is usually not prescribed temperature. In determining such standards of measurement methods and allowable temperature rise, should consider the following factors, such as the characteristics of the structure, thermal conductivity and thickness of the insulation of each part of the easy detection of insulation, ventilation methods, load characteristics. 

3.1.4 Other Factors 

   The ability to maintain its insulating effectiveness factors in addition to the heat, is also affected by certain conditions (such as the insulation is applied to the support structure and the mechanical stress), and some of the factors (such as vibration and differential thermal expansion) in the. With the increase of the product size, the effects of vibration and thermal expansion factors become more important. The temperature of the atmosphere, and the presence of dust, chemical substances or other contaminants can have a detrimental impact. In the design of a particular product, these factors should be considered. Detailed assessment and guidance materials to identify the electrical equipment insulation structure. 

3.1.5 Use of the insulating 

   The actual use of the product depends on the electrical operation of the specific conditions. These conditions may vary considerably with the different environment, the duty cycle and the product type. In addition, also depends on the intended use of the product size, reliability and the intended use of the equipment as well as economic and other requirements. 

   For some electrical products, because of their specific application purposes, require the use of insulation on lower or higher than normal, or because of the special operating conditions, the provisions of its temperature is higher or lower than normal, and it insulated high temperature at or below normal. 

   The use of insulation is largely dependent on the degree of isolation of its oxygen, humidity, dust and chemical substances. At a given temperature, by the use of appropriate protection of the insulation will be freely exposed to the atmosphere than the use of a long insulated, therefore, with a chemically inert gas or a liquid for cooling or protection price quality, the use of extended insulating. 

3.1.6 operating temperature limit 

   In addition to the aging of the insulation to withstand the outside, some of the material is heated above a certain temperature will soften, or other deterioration, but later restored to its original cooling performance. Note that the use of such material, be sure to make them work within the proper temperature range. 

3.2 insulation choices and determine 

   Electrician product research, design, manufacturing units should select the appropriate limits of insulation materials and structures according to the insulation temperature. Determined based on the temperature limits of the insulation is only reasonable operating experience or suitable, acceptable tests. Operating experience is an important foundation for selecting insulation materials and structures. However, when the use of new materials and new structures, the appropriate test is the basis of this choice (see clause 4.2). 


4 Heat assessment 

Heat-resistant insulating material Assessment 4.1 

   Many insulating materials of the same genus in heat resistance can be very different. Thus, the chemical name according to the genus of insulating material determining their heat resistance is not appropriate. 

   Insulation for electrical products in a variety of insulation materials, each of which may be affected by the heat resistance of other materials. In addition, the heat resistance of various materials to a large extent, they also depend on the assumed structure of a particular function of the insulation. 

   The insulation material used in the electrical products concerned, material assessment has two purposes: First, as an integral part of the electrical insulation of a material evaluation, and the other is used alone or in combination as a simple form of insulation evaluation of a part of a material. 

   In general, assessment tests and operational experience are recognized as an acceptable basis for assessment of thermal insulation material. 

   When you want to run based on the experience Note: You must ensure that the experience is applicable. However, in some cases, will be diverted to an experience is often another application may also be suitable. Suitable methods should be developed to determine the relationship between operating experience. 

   Test methods for evaluation of research material significant progress has been made. In determining the e­xpression of heat resistance and insulating materials have been more perfect, which can be found in GB 11026.1, and will also develop other parts of the Guide is. 

   Pair of a material with different properties (such as electrical, mechanical, etc.), standard methods for heat and failure Figure, it is possible to obtain different temperatures the difference between the index and a half. Different temperature index and half the difference between the heat resistance of the show is different, the decision cited by the use of the material and the way it can assume the functions. 

   The results obtained with the standard sample test results may be related to their actual use in the form of test material was different. Insulation structure closer to the actual situation. Therefore, the results of testing insulation material can prove the applicability of the relevant application. 

4.2 Assessment heat insulation structure 

   Valuation heat-resistant insulating structure, it is best used as a basis for the relevant operating experience. When no such operating experience, it should be appropriate functional tests. For this purpose, the need for a proven operational experience as a reference structure insulated structure. Assessed by comparing its new heat-resistant insulating structure. Research units and electrical insulation product research, design, manufacture, testing, use of units should be designed and carried out the appropriate tests. In the design of appropriate standardized tests and the development of testing procedures for evaluation of heat resistance, should be assessed with reference to the relevant information insulated structure. 

   In selecting the components of the insulation structure, heat resistance evaluation results can refer to a single material (see section 4.1). 

   As long as the appropriate structural insulation test or operating experience has proved its operational characteristics of a dielectric material satisfaction, we can ascertain whether the material for a particular insulation structure. Without considering the heat resistance of the material itself. 

   For a very simple structure and insulation stress by a single action, according to the specific circumstances of the decision, is the need for functional testing insulation structure; still relatively simple to evaluate the data based on the heat resistance of the material, you can get satisfactory results. If you need to evaluate whether the material is applicable to a certain electrical products, you should have proven experience running a suitable material for reference materials, conduct the test. In this regard, the units should provide information in specific applications proven operating experience of the material. Meanwhile, in order to be properly graded material should also provide guidelines on how to evaluate operating experience. 

   Should develop standardized test procedures applicable to comparative assessment. When no such standardized testing procedures, research units and electrical insulation product research, design, manufacture, testing, and use of appropriate testing procedures should be selected for testing. 


5 Classification 

   Electrical insulation and heat resistance of the product classification see section 3.1 (especially 3.1.5 and 3.1.6) and Section 4.2. 

   If you show a certain insulation materials, insulation structure consists of a simple combination or test or operational experience in a particular application, can reliably operate at a specific temperature, you can give it an appropriate heat levels under Article 3.1. 

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