Requirements and Judgment Standards for Glow Wire Testing

What is Glow Wire Testing?
Glow Wire Testing is used to test the stabilities of electronic and electrical products when in operation. The glow wire itself is a fixed-size coil of resistance wire and during the test, the resistive wire needs to be heated with electricity to a predetermined temperature so that the top of the glow wire can contact the sample for a predetermined period of time and then observes and measures its status. The testing range depends on the specific test procedure.

The Glow Wire Tester heats the resistive wire of a prescribed material (∅4 Ni80/Cr20) and shape with a large current to a testing temperature (550℃～960℃) for one minute, then vertically making contact with the sample with a prescribed force (1.0N) for 30 seconds.

It is judged whether the sample or cushioning material catches fire or flames, in order to determine the ignitability of the manufactured electrical or electronic devices. In order to determine the ignitability, ignition temperature (GWIT), flammability and flammability index (GWFI) of solid insulation materials and other solid combustible materials.

Purposes and Scope of Glow Wire Testing It is used to test the stabilities of electronic and electrical products when in operation. When components or parts may reach too high a temperature or ignite materials in the vicinity of them under fault or overload condition, the simulated technique shall be used to estimate the ignition hazardous.

Glow Wire Testing is applied to electrical and electronic equipment and its components and parts, and applicable to solid insulation materials and other solid combustible materials, e.g. switch case, relays, sockets, etc.

Necessity of Glow Wire Testing for Lighting Fixtures: For the household appliances industry, safety has always been a topic of concern. Due to misuse, electric wiring may cause current overload or short circuit which could lead to combustion of plastic materials. Therefore, fire prevention requirements were drawn up to evaluate and measure the combustibility of the materials used in the appliances. Glow Wire Test (Glow Wire Testing) is one of the related fire prevention requirements currently adopted by the household appliances industry.

Requirements for Hot Wire Tests on Luminaires According to the requirements, the requirements for hot wire test temperature for each part of the luminaire structure are different, as follows:
1. For the lowest level that may ignite parts and cause fire hazards, the hot wire test temperature is 550 degrees;
2. For normal usage equipment, the hot wire test temperature is 650 degrees;

3. For equipment used under harsh conditions and installation with fixed accessories, the hot wire test temperature is 750 degrees;
4. For equipment used without supervision under continuous load, the hot wire test temperature is 850 degrees;

5. For equipment used without supervision under continuous load under harsh conditions, which is intended to be used near building power points, the hot wire test temperature is 950 degrees.

Hot Wire Test Pre-treatment:
A very important preparation step for material fire resistance testing is pre-treatment. The sample will have different ignitability, flame spreadability and self-extinguishing capability under different temperature and humidity conditions.

Therefore, in order to allow comparison between each hot wire test, it is necessary to prescribe the pre-treatment temperature, humidity and time. According to the standard, the sample and backing layer must be placed in ambient temperature of 15℃~35℃ and relative humidity of 45~75% for 24 hours before the test.

The laboratory should be equipped with a temperature and humidity meter. If the ambient temperature and humidity do not meet the requirements, the atmospheric environment should be regulated by an air control device.

Determination Criteria for Hot Wire Test:
GWFI Determination If any of the following conditions are met, the specimen shall be considered to have passed the test:
a) If the flame or glowing of the test specimen extinguishes within 30 seconds after the hot wire is removed;
b) The wrapping paper does not ignite. GWFI should be recorded as follows: e.g., for a 3 mm thick specimen and the test temperature is 850 °C, record as GWFI: 850/3.0.

If the conditions are not met or only one of them is met, a lower test temperature should be selected and a new specimen should be tested.

GWIT Determination：
The ignition temperature of the specimen during the application of the hot wire shall be determined. The test temperature higher than the highest temperature of the hot wire in three consecutive tests, which does not cause the specimen to ignite, shall be recorded as GWIT. GWIT shall be recorded as follows: e.g., for a 3.0 mm thick specimen and the highest test temperature that does not cause ignition is 825 °C, record as GWIT: 850/3.0.

The determination of the result of the Burning Wire Test:
After the test is completed, according to the standards and the test phenomenon, the results of the test should be determined in order to decide the qualification of the material. The time for the Burning Wire Test is 30 seconds, and the Burning Wire will automatically withdraw after 30 seconds. During this period, the afterglow should be recorded with a metering and qualified timing device.

If the sample does not ignite during the Burning Wire’s application, or extinguishes automatically within 30 seconds after the incinerator withdraws, and there is no ignition of the underlayment during the test, the test will be judged qualified.

All factors that affect the flame combustion should be considered masked, such as the flow of air, the residual substances left on the Burning Wire from the previous test, etc. If there is a sample residue left on the Burning Wire after it has withdrawn, the afterglow of this part of the sample should not be used as the basis for judging the results.

If the majority of the sample residue left on the Burning Wire is flaming, this phenomenon should be recorded in the test report. The height of the flame is not a determinant of qualification, but it can also be recorded in the test report as a reference data for flame resistance.

As an important indicator for measuring the fire resistance of materials, the Burning Wire Test is a test that is frequently conducted in product certification. How to strictly carry out the Burning Wire Test according to the standards is very important. Only by correctly conducting the Burning Wire Test can the fire resistance of the product be accurately measured, and the fire safety performance of the product can be ensured.

The ZRS-3H Glow-wire Test Apparatus is according to IEC60695-2-1, IEC60695-2-10, IEC60695-2-11, IEC60695-2-12, IEC60695-2-13 (GB/T5169.10, GBT5169.11, GBT5169.12, GB/T5169.13) < basic testing methods of Glow wire, basic testing methods of Glow wire device>, UL 746A, IEC829, DIN695 and VDE0471.

ZRS-3H Glow-wire Test Apparatus

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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