GB 5169.6-1985 Test method for poor contact of heaters used in fire hazard tests for electrical and electronic products
Some standard content:
1. Introduction,
National Standard of the People's Republic of China
Fire hazard testing for electronlcand electronic products
Test method of bad connection wlth heater UDC 621.8. 002. 6
1536.468,001
.4:821.816.5
GB 5169.6-85
Fire hazard testing for electronlcand electronic products is best to completely reproduce the conditions that occur in reality, but this is impossible in most cases. According to the actual situation, the test simulates the effects that occur in reality as much as possible. 1.1: Test purpose
Bad contact refers to the fault state of the connector terminal that generates abnormal heat. For example, looseness, insufficient mechanical pressure, installation that does not meet the specifications, or excessive heat loss dissipation (depending on the product design and the current flowing through) may lead to this state. After a long period of time, the insulating material that keeps this joint in place will be unduly affected. The bad contact test with a heater simulates overheated contact, which takes into account the design of the contact and the current flowing through it under rated conditions, and uses simulation technology to assess the fire hazard. 1.2 Scope of application
This standard applies to connectors and terminals connected by screws in electrical and electronic products, components and parts with a rated current not exceeding 63A. Note that the heaters specified in Chapter 3 are not applicable to connectors and terminals other than screw connections. They are only suitable for testing terminals of various designs and sizes of screw connections as specified in Appendix A. If the test sample ignites according to this standard test, the resulting combustion hazard needs to be tested using other ignition sources such as the needle flame method.
1.3 Others
This standard is equivalent to the first edition of the international standard 1EC 695-2-3 (1984). 2 Requirements for test samples
The test sample should be a complete product, component, part or component as much as possible. If necessary, the test can be carried out after the shell is completely or partially removed.
6. If the test cannot be carried out on the complete test sample, an appropriate part can be cut off for testing. If the test cannot be carried out on the components or parts inside the product, the test can be carried out on a sample of a separate corresponding component, part or component c.
8 Test equipment
3.1 The test heater consists of an alloy wire, which contains not less than 59% nickel, 14% to 10% chromium, and 19% to 23% iron. Its resistivity at 20°C is 1.132-mm*/m. This wire has an appropriate length and shape. Each end of it is connected to a copper strand with a length of 120±2 mm and a round cross-section composed of fine copper wire with a brass tube. The copper sleeve is flattened, clamped, and then welded. 3.2 Shape of the resistance wire. The diameter and length should be adapted to the size and design of the connector or terminal to be tested. According to the actual current flowing through the connector or terminal, the corresponding test power should comply with the provisions of the table in Chapter 4. National Bureau of Standards 18B5-04-26 issued
1986-02-01 implementation
GB5169.6--85
In order to avoid overheating and melting of the test heater, the unit surface load related to the length and diameter of the resistance wire specified above shall not exceed the specified value.
When the actual value of the unit area load n is expressed in W/mm2, it can be calculated according to the following formula: N
Where: N——test power, W,
d—-diameter of the resistance wire, mm;
Lh—free length of the resistance wire, mm.
In order to determine the minimum allowable diameter of the resistance wire, it is necessary to compare it with the maximum value (πmx). If d>1.0mm, nmax0.36W/mm2
dh=0.5mm, nmx*0.40W/mm2,
The selection of the diameter of the lead wire and the copper sleeve connected to the resistance wire is based on the heat dissipation of the conductor (special hard or soft type) connected to the test connector or terminal under normal use. In order to insulate the surface of the resistance wire, a surface oxidation treatment is required. It is required to energize the red-hot test heater under normal atmospheric conditions. In order to verify the test heater later and find any deterioration, the cold resistance of the strands at both ends should be measured and recorded when the strands are new.
Note: For connectors of certain shapes and designs, Appendix A gives guidelines for the manufacture of test heaters. When other screw-tight connectors are tested, the guidelines for the manufacture of test heaters can also refer to Appendix A as appropriate. 3.3 The test heater is powered by an adjustable low-voltage transformer to achieve the specified power. The voltage and current meters for measuring the voltage drop across the test heater and the current flowing through it should be accurate to 1% (i.e., level 0.5). If a power meter is used, the accuracy should be at least 1.5%.
3.4 In order to assess the spread of combustion, place a layer of sub-layer under the test sample. The sub-layer is generally composed of materials or components around or under the test sample, and its distance from the bottom of the test sample should be consistent with the actual use in the product.
Unless otherwise specified in the relevant standards, when the components or parts of the product are tested separately, a piece of white pine wood board about 10mm thick covered with silk paper is used as the sub-layer, which is placed 200±5mm below the flame application position of the test sample. Note: Silk paper is a soft and strong lightweight packaging paper with a specific gravity of generally 12 to 30g/m2.3.5 The test equipment should be able to fix the burner, test sample and sub-layer in the specified position. 4 Severity level
The test power and duration applied to the test sample should be specified. The following table gives the test power values determined according to the actual current flowing through the connector and terminal. The preferred application duration is 30 minutes.
The permissible error value of the test power is ±5%
Other severity levels may be used if required by the relevant standards. Pretreatment
Current, A
> 0.2 ~ 0. 5
> 1.5-2.0
> 2.5~3. 0
> 3.0~4.0
> 5.0~6. 0
> 6.0~8.0
> 8.0~10.0
>10,0 ~13,0
>13,0 16,0
>16.0 ~20.0
>20.0 ~25 .0
25.0~32.0bzxz.net
32.G～40.0
40.0~50.0,
>50.0~63.0
GB 5169.6-B5
Test power value
Test power, W
Unless otherwise specified in the relevant standards, the test samples are generally treated in the atmosphere of temperature of 15～35℃ and relative humidity of 45%～75% for 24 hours before starting the test.
Initial measurement
The test samples are checked with 1 test, and when the relevant standards have provisions, the physical and electrical parameters are measured. 7 Test procedure
7.1 Safety precautions
When conducting the test; personal safety protection measures must be taken for the following points. Burning or explosion hazard:
b. Inhalation of smoke or toxic bio-warfare 1
c. Toxic residue.
7.2 The test sample shall be placed in the most unfavorable position in actual use for testing. Its fixing method and the connection between the test heater and the power supply shall not cause differences from the actual use conditions and affect the test results. 7.3 When all or part of the casing is removed from the complete product, component, part or component for testing, it shall be ensured that the test conditions have no significant differences in shape, air circulation, thermal stress effects and possible flames and hot burning particles falling near the test sample.
7.4 According to the design of the tested joint or terminal and the current flowing through it, insert a heater of appropriate size and shape into the joint or terminal so that the heat generated by it is as close as possible to the place where poor contact is likely to occur. And minimize the thermal stress of other parts except the test part. 7.5 Use screws or other fastening methods to gently tighten the joints or terminals to prevent the test heater from coming out during the test, and ensure that the oxide film of the test heater is not damaged to avoid causing local shunts or short circuits in the heater. If the metal parts are displaced due to the action of springs or similar things during the test, the mechanical loads such as springs should be adjusted to the same as normal use. 7.6 A low voltage transformer is used to pass current through the test heater and is adjusted to the specified power. To control the test power, the current through the test heater and the voltage drop across the test heater are measured. The voltage drop is measured between the "cold" ends of the strands of the resistance wire. Unless otherwise specified in the relevant standards, the test power is generally applied for 30 minutes. The power is cut off until the test results are recorded, and the test heater remains in its original position.
7.7 Three test samples are generally required. When the relevant standards require more than one connector (or terminal) to be tested on the same part of the product, it is necessary to ensure that the deterioration caused by the previous test does not affect the test results of the subsequent tests. Note: If the connector or terminal and their support are designed symmetrically, it is sufficient to test only one connector or terminal. 7.8 The test heater must be checked regularly to see if the resistance changes excessively due to deterioration. If the heater is measured in free air and the difference from the original value is equal to or greater than 10%, the heater must be scrapped. 8 Observation and Measurement
When the test power is applied and the test sample cools down to near room temperature, the test sample and the surrounding parts and the underlying substrate shall be observed and recorded.
6.1 When the test sample and the surrounding parts or the underlying substrate catch fire, the burning duration shall be measured and recorded. The burning duration is the time interval during which the flame can be seen with the naked eye on the test sample, the surrounding parts or the tested substrate.
B.2 The highest height of the flame, but the high flame that may be produced for about 1s at the beginning of the fire is not counted. The flame height is the vertical distance between the visible top of the flame and the upper surface of the burning object. 8.3 Characteristics of combustion
8.4 The test sample shall be visually inspected for physical damage after the test. If specified in the relevant standards, measure mechanical and electrical parameters. 9 Evaluation of test results
Unless otherwise specified in the relevant standards, the test sample can be considered to have withstood the poor contact test if it meets one of the following two conditions. a. No flame, no continuous burning:
b. If the test sample, its surrounding parts or the underlying substrate produce flaming combustion or burning, but it goes out within 305 after ignition, and the surrounding parts and the underlying substrate are not completely burned. When the underlying substrate is covered with silk paper on the pine board; the silk paper should not catch fire, the pine board should not be charred, and the slight discoloration of the pine board can be ignored. If the piano parts around the test sample need to be tested with other suitable ignition sources, the height of the flame should be measured and recorded during the poor contact test.
10 When this test method is adopted in the relevant standards. The following items should be specified: pretreatment conditions,
the number of test samples, if not three: fixation of the test sample;
the tested joints or terminals and suitable heaters; the underlying substrate used to assess the spread of combustion; the severity level; the test power value; the application duration (if not 30min). f.
whether the test is carried out on more than: joints or terminals on the same product. 。 Which of the two conditions specified in Chapter 9 should be used for fire hazard assessment? Whether the standards specified in Chapter 9 meet the safety requirements, and whether other standards should be specified. i. The allowable degree of degradation of electrical and mechanical properties. A.1 Introduction
GB 5169.6-85
Appendix A
Guidelines for the preparation of test heaters
(reference)
In order to conduct poor contact tests on connectors and terminals, a test heater is constructed with resistance wire. The shape of the test heater is related to the size and design of the connector (or terminal), and the test power is considered based on the actual current passing through. The test heater that connects the external copper conductor to the internal terminal of the electrical equipment with screw connection can be prepared according to the following instructions. Taking into account the provisions of Chapter 3 of this standard, this guide can also be applied to the preparation of test heaters for terminals of other shapes and sizes. A.2 Composition of the test heater
The test heater consists of a nickel-chromium alloy wire with a nickel content of not less than 59%, a chromium content of 14% to 19%, an iron content of 19% to 23%, and a resistivity of 1.132 mm2/m. Each end of the test heater is connected to a 12±2 mm long thin copper wire or a round cross-section strand by a brass sleeve (Figure A1). The copper sleeve is clamped and soldered with a silver solder containing at least 40% (Figure A4). The preparation of the test heater requires a pair of pliers with matching inserts or other equivalent flattening clamping tools. When preparing a spiral test heater, a circular mandrel of appropriate size is required. A.3 Dimensions and shapes of the test heater
Corresponding to Table A2 Table A1 specifies the type of test heater and the dimensions of its resistance wire, multi-core lead wire, and copper sleeve connector before and after clamping.
Table A2 specifies the number and type of test heaters with screw terminals. It is necessary to ensure that the size and shape of the test heater, in particular the free length and size of the resistance wire and the multi-core lead wire, are suitable for the space of the conductor of the test connector (or terminal), and are compatible with the heat dissipation caused by the maximum current of the rated cross-section flowing through the conductor and the connector (or terminal) during normal use.
A.4 Preparation of the test heater
A.4.1 The copper alloy sleeve can be slid into two 120mm long lead wires. Care should be taken to ensure that a pair of lead wires do not cross and no individual core wire protrudes from the copper sleeve.
A.4.2 Using suitable pliers or pressure tools, flatten the copper sleeves parallel to the ends of the two lead wires. This end is called the "cold end". A.4.3 Using suitable tools, install another copper sleeve on the other end of the two lead wires. Use a pointed rod (sewing needle) to make a hole in the core wire of the copper sleeve in the center of the cross section so that the resistance wire can be inserted. A.4.4 The resistance wire is inserted into the holed ends of the two lead wires. A.4.5 Use appropriate tools or pliers as shown in Figure A4 to insert the resistance wire into the copper sleeve at the end of the lead wire and press it tightly and carefully ensure that the narrow side of the copper sleeve is in the same plane after being pressed. The copper sleeve is pressed over the entire length (including the "end" with a hole in the lead wire). c. After the copper sleeve is pressed, a and b must comply with the requirements of Table A1. In .4.6, the joint between the resistance wire and the lead wire is flattened and then welded. A flux with appropriate melting solder can be used. The solder is supplied from one side of the resistance wire to the flattened joint. Careful consideration must be given to ensure that there is no residual solder and excess solder in the copper lead wire for a length of L mm, because they can affect the mobility and thermal conductivity of the lead wire. Figure A5 shows an appropriate welding tool. A.4.7 According to the test requirements, the test heater is formed into U-type, W-type, C2 or C3 type, see Figure A2 and Table A2. The diameter of the resistance wire does not exceed 1.2 mm and can be bent at room temperature Bend into the required shape. If the diameter of the resistance wire exceeds 1.2mm, it is hot-bent to avoid cracking. The U-type is formed by passing an appropriate current through the test heater or heating it with a gas flame.
For U-type and W-type, it must be carefully ensured that the narrow side of the flattened copper sleeve is in the same plane and the resistance wire is not bent. A.4.8 The test heater is powered on and red hot under normal atmospheric conditions. Keep it at this temperature for 10 minutes to oxidize its surface to form insulation.
Test heater
To: ① Maximum value (mm).
② Minimum value (mm).
@High flexible lead wire.
④ Assumed value.
GE $16s.6--85
Type and size of test heater
Test heater
Before flattening the sleeve
After flattening the copper sleeve
GB 5169.6—B5
Table A2 Number and type of test heaters with screw-connected terminals Type of terminal
Screws are bolt-type
*The actual current flowing through the terminal under rated conditions. Current*, A
. Number of test heater
HS0/C1
HS1/C2
HS2/C2
HS3/C2
HS4/C3
HS5/C3
HS6/C3
HS7/C3
CB 5169.685
Figure A1 Size of resistance wire
1 Resistance wire, diameter dh, 2-lead wire, length 120±2 m 3-Copper sleeve C, and C type
Figure A2 Size and shape of test heater
Before fan
Figure A3 Size of copper sleeve
Figure A4 Example of fan tool
After flattening
Additional instructions:
GB5169.6-85
Figure A5 Example of welding equipment
1-Resistance wire, 2-Lead wire; 3 Copper sleeve after compaction, 4-Fireproof support This standard is proposed by the National Environmental Technical Standardization Committee for Electrical and Electronic Products (abbreviated as Environmental Standardization Committee). This standard was drafted by the Fire Hazard Working Group of the Environmental Standardization Committee. The main drafter of this standard is Liang Xingcai of Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry.6-85
Figure A5 Example of welding equipment
1-resistance wire, 2-lead wire; 3-copper sleeve after compression, 4-fireproof support This standard is proposed by the National Environmental Technical Standardization Committee for Electrical and Electronic Products (hereinafter referred to as the Environmental Standardization Committee). This standard was drafted by the Fire Hazard Working Group of the Environmental Standardization Committee. The main drafter of this standard is Liang Xingcai of the Guangzhou Electric Science Research Institute of the Ministry of Machinery Industry.
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