GB/T 5169.3-1985 Fire hazard tests for electric and electronic products - Technical requirements for fire hazard assessment of electronic components and guidelines for the formulation of test specifications

GB/T 5169.3-1985 Fire hazard test for electric and electronic products Technical requirements for fire hazard assessment of electronic components and guidelines for the formulation of test specifications GB/T5169.3-1985 Standard download decompression password: www.bzxz.net

1 Introduction
National Standard of the People's Republic of China
Fire hazard testing for electric and electronic products
Guidance for the preparation of technical requirements and test specifications for assessing flrehazard of electronic components When conducting fire hazard tests on electronic components, the following factors should be fully considered: UDC 621.3.002.6
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GB 616.385
, 'Various electronic components are made of different materials and are installed in various different equipment. The arrangement of the components in the equipment is relatively tight, and the intervals between them are very small. It is difficult to predict what kind of situation they will encounter during use. b. Electronic equipment uses electrical energy to maintain its normal operation. Some electronic components (such as relays) may generate sparks when in use, but their heat loss is usually very small. However, when electronic components fail or work in an abnormal state, they tend to emit a lot of heat.
c. The number of electronic components used in equipment is often large. Due to their different functions, they are in different working states, which makes it difficult to describe them with a unified indicator. Not all electronic components have the same fire hazard. Only some electronic components are particularly prone to fire and are particularly harmful. Fire hazard tests and research work are carried out on these electronic components.
This standard is equivalent to the first edition of the international standard IEC695-1-2 (1982). 2 Fire hazard concept
2.1 Generation of fire hazard
When electronic components are overloaded due to internal defects or external failures, they will generate excessive heat to the extent of ignition.
Flames may be caused by any of the following: a. The component itself is overheated and catches fire. b. The component itself is so hot that it ignites parts that are in contact with it or very close to it. Other parts are caught fire by hot particles falling from the explosion of the component or by hot materials falling when burning. When there are flammable concentrations in the air and it is conducive to the combustion of components or other objects, the radiation from components that can burn spontaneously or by nearby sparks will cause the space in which it is located to burn. Note that components can also catch fire in other ways, such as flying solitaries or leakage. 2.2 Spread of flames
The spread of flames is determined by the following conditions: b. The total energy available in the burning component.
Issued by the National Bureau of Standards on April 26, 1985
Implemented on February 1, 1986
b. The rate of energy release.
c. The duration of combustion.
d. The ease with which adjacent components catch fire.
GB 5169.3—85
e. The design and installation characteristics of components in the equipment, that is, the spacing between components, ventilation status, etc. 3 Main purpose
Through reasonable design, the equipment will not cause fire hazards under internal defects or overload conditions. This is the primary task of the equipment manufacturer. To this end, one or more of the following methods can be used to achieve: the rated power of the components is higher than their actual load power when working, and the load power (especially resistors) components can cause open circuits and interrupt line operation when overloaded. The natural characteristics of the components are determined by the maximum fault power of the circuit. b: Use heat shielding or heat dissipation devices to prevent dangerous components from catching fire. C. There should be a large enough distance between adjacent components to dissipate excess heat. d. Use additional devices such as voltage or current limiting devices, fuses, etc. to protect dangerous circuits. In special cases where the above methods cannot be applied, dangerous components should meet the specified safety requirements. To this end, the following two related characteristics must be obtained separately to determine the potential fire hazard of electronic components:. The spontaneous combustion test
is used to determine whether a faulty or overloaded component can catch fire and the degree of combustion, as well as the time when the flame spreads. b. The ignition test
is used to determine the ease with which a component can be ignited by a flame or an adjacent heat source, as well as the degree of combustion and the time it takes to cause the fire to spread.
4 Types of ignition tests
The ignition test includes two types: natural test and ignition test, both of which can achieve the following two purposes: 1. Provide the combustion characteristic data of the basic component so that the equipment designer has actual data to check. If necessary, the corresponding standards can also be obtained through the component ignition evaluation test. The purpose of the combustion characteristic test is not to identify whether a certain component is qualified or failed, but to provide data for evaluating the potential ignition hazard of the component, which serves as a basis for the manufacturer, user or relevant technical department to formulate component specifications. If necessary, it can be used for acceptance inspection to determine whether the component can pass this inspection. The severity of the test and the selection of acceptance criteria should be consistent with the actual situation of the ignition hazard that the component may encounter in a special application. 5 Temporary fire test and its evaluation,
5.1 Combustion characteristics test
The best way to carry out fire hazard test of electronic components is to repeat the actual situation and accurately simulate the actual use conditions and environmental conditions of electronic equipment. But generally speaking, this is difficult to achieve. Because various electronic components are installed in various types of equipment in considerable quantities, they work in various different states and play their respective functions. Therefore, it is impossible to determine a working condition and environmental condition applicable to all components, but only to reasonably simplify the actual situation and use the fire hazard test method that can reflect the actual use and has typical significance-electronic component combustion characteristics test method. The combustion characteristics test is a designed procedure for measuring or evaluating the characteristics displayed by electronic products under various combustion conditions. The combustion characteristics test results provide information that helps to evaluate and control the fire hazard and find the most appropriate factor among several factors that need to be considered.
5.2 Spontaneous combustion test
5.2.1 Purpose of spontaneous combustion test
Determine whether a faulty or overloaded component can catch fire, the degree of combustion, and the time when the flame spreads. 5.2.2 Spontaneous combustion test methodbzxZ.net
GB 5168.385
A test method using a step-by-step electrical overload to failure. The test is appropriately continued until the component is completely destroyed (or failure occurs when the overload heat source is effectively removed), or the test is continued until the overload level reaches the application limit (it should be maintained for a period of time to achieve thermal stability with the surrounding environment). The nature, level and complete failure of the overload should be recorded. The following combustion characteristic data of the component should be recorded: when the component smokes; when the component burns hot; when the component catches fire, the flame height when the component burns, the duration of the component burning, and the substances released when the component burns: the surface temperature of the non-combustion parts.
6.2.3 Spontaneous combustion hazard evaluation
The combustion characteristics obtained from the spontaneous combustion test can be used as a basis for determining whether the component can pass the spontaneous combustion hazard test. By testing the components under the specified failure or maximum overload or maximum power consumption state, it is determined whether the specified combustion standard or surface temperature standard is met.
In the absence of technical specifications for fire hazard tests, the information obtained from the study of spontaneous combustion fire hazard tests can be used as the basis for formulating technical specifications for spontaneous combustion fire hazard tests for electronic components. 5.3 Ignition test
5.3.1 Purpose of ignition test
To determine the ease with which a component can be ignited by a flame or an adjacent heat source, as well as the degree of combustion and the time for flame spread. 5.3.2 Ignition test method
The ignition test should adopt different methods according to the different sizes of the samples. The following are two typical test methods: Needle flame test method
It simulates the electronic equipment under fault conditions such as loss current flowing through the leakage path. Whether a small local flame such as component overload, poor contact, etc. will cause nearby components to catch fire.
b.Glow-wire test method
It simulates whether the thermal effect of electronic equipment under fault conditions (such as a hot component or overloaded resistor in a short period of time) will ignite nearby components.
The degree of ignition fire hazard is related to both the applied stress level and the combustion characteristics of the component. Therefore, these parameters should be recorded:
Flame height and application time (pointer flame test): Glow-wire temperature level and application time (referring to glow-wire test)! Ignition time, that is, the time from the component being exposed to the specified heat source until the fire occurs; Afterburning, the time the component continues to burn after leaving the heat source; The ability of flame spread, that is, whether there are hot particles or hot materials falling and causing the flame height of the underlying ignition component to ignite the underlying layer;
The amount of smoke (gas) released during combustion. 5.3.3 Ignition fire hazard evaluation
The combustion characteristics obtained from the ignition test can be used as a basis for determining whether the component can pass the ignition fire hazard test. By testing the components under the specified position conditions and the applied heat energy conditions, it is determined whether the specified standards are met when a specified heat source is applied. In the absence of technical specifications for fire hazard tests, the results obtained from the study of ignition fire hazard tests can be used as the basis for formulating technical specifications for ignition fire hazard tests for electronic components. 5.4 Other effects
GB5169.3-85
When conducting self-ignition characteristics tests and ignition characteristics tests, other effects should be observed and recorded, such as: the emission of molten burning materials and hot particles, the spread of explosives, smoke and corrosive emissions or toxic gases, which may be important in certain applications and may be a more serious hazard than fire. Additional remarks:
This standard was proposed by the National Technical Committee for Environmental Conditions and Environmental Testing of Electrical and Electronic Products (hereinafter referred to as the Environmental Standardization Committee). This standard was drafted by the Working Group on Fire Hazard Tests for Electrical and Electronic Products. The main drafters of this standard were Chen Haohua and Zhang Xingfa from the Fifth Research Institute of the Ministry of Electronics Industry.
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