What is the glow wire test apparatus?

The glow wire test apparatus investigates the fire-resistant properties of raw materials and finished components. LISUN’s glow wire test equipment has been ergonomically designed to meet the above EN and IEC standards.
Fire originates from the glow wire itself. A temperature programmer is used to establish and regulate the glow-starting wire’s temperature. By switching the temperature controller to manual mode, a steady voltage signal may be sent to the glow wire, preventing the sample from experiencing a change in output power due to feedback from the control thermocouple.

What is the glow wire test?
Tests for potential fire hazards in electronics, home appliances, and other electrical goods may be performed using a glow wire test apparatus. It mimics a situation in which a nearby ignition source (such as a hot element or an overloaded resistor) causes surrounding combustible materials to ignite and flame to spread rapidly, leading to the burning of insulating materials or other solid combustible materials.

Description of apparatus
Lighting equipment, low-voltage electrical appliances, electrical instruments, and other electrical and electronic items and their components are all ideal candidates for use with glow wire test apparatus in research, manufacturing, and quality inspection.
IEC 60695-2-10, UL746A, and other standards use a non-flame ignition source program, and the glow wire test equipment is used to simulate this.
Searing components or glow wires in a glow-wire testing apparatus might ignite insulating materials or other solid combustibles, causing a fire inside the device.
Components may overheat and catch fire if specific circumstances are met, such as an excess of fault current elements running through the wires or a breakdown in contact.
With modeling approaches, glow-wire testing devices can determine the potential for thermal stress induced by burning components or overload resistances in a short time. Useful for anything involving electricity or electronics, including solid electrical insulation or other solid flammable materials.

Figure: Glow wire test apparatus

Importance of Glow wire test apparatus
Since it is not always feasible to replicate identical circumstances to assess the fire dangers of electrotechnical items, the best approach to assess the fire hazards of such products is to model the real effects happening in practice as closely as possible.
It should perform a fire risk assessment on any electrotechnical equipment containing insulating material or any other solid combustible substance that might potentially spread flames within the glow wire test apparatus.
Components, wires, and even connections may catch fire if they reach a high enough temperature due to a fault current running through a wire or an overload.
To analyze the potential for a fire using a simulated method, the glow wire test device has been developed and built to measure the impact of thermal strains caused by transient heat sources like glowing components or overloaded resistors.
If a product is made using unapproved combustibles, there is a greater chance of a fire breaking out for various causes when the product is in use. That’s why using the glow-wire test for materials quality assurance is important. Some of the following situations might spark a fire in flammable materials:

1. Combustible materials may catch fire if the device is turned on while the live connection portions are not making proper contact.
2. The flammability of the device’s supporting materials is increased when the gadget is turned on, and the interior temperature of its components increases to a dangerous level.

Glow Wire Tester Parts

The glow wire testing device is a fire detector that employs an artificial spark as an ignition source.

Glow wire: It’s an 80/20 nickel/chromium (4mm) wire loop. The tip of the glow wire is protected by a metal that can withstand temperatures of at least 1050 degrees Celsius, and within is a tiny thermocouple with a diameter of 0.5mm that can measure the temperature of the light during continual operation up to 960 degrees Celsius.
Temperature display: The term voltage measurement device has a 1% accuracy.
Temperature control: There is a cap on the voltage that may be used to heat or cool the glow wire. After enough time for stabilization has passed, the relevant temperature is shown on the temperature display.
Weight: It allows a force of 1.2N to be delivered to the specimen as it is placed against the glow wire.
Hazard tray: Its purpose is to evaluate the risk of fire spreading from dropping glowing or burning particles from the specimen. The top layer of masonite may be easily removed and replaced if required.
Timer: Used to determine how long a specimen was exposed to a glow wire.
Specimen clamps: These have been created with minimal surface area, reducing the interference with heat displacement from the object under test.

Summary of Test Method

1. The Glow Wire Tester has feet that it may adjust for a level reading.
2. Place the specimen in the specimen clamps with the surface perpendicular to the tip of the glow wire. This surface will be subjected to heat stresses during typical operation. It may alter the vertical position of the specimen clamp for convenience.
3. Remove any residue from earlier tests by cleaning the glow wire’s end. You may use a wire brush.
4. It would help if you let the sample roll up against the Glow Wire. The penetration depth may be adjusted, stopped, and locked in the desired position. Bring the carriage back to its original stopping point and maintain that posture.
5. Be sure to keep the glow wire at the specified temperature but at a safe distance from the specimen to prevent any damage from radiant heat. When the ideal temperature has been attained, note your coordinates to use as a guide for the next time.
6. Begin timing at the allotted exam time.
7. You may begin the test by removing the carriage stop and then rapidly pushing the timer start button.
8. Keep an eye out for flames and measure their height throughout the test.
9. When the timer beeps, it’s time to put the carriage back where it belongs and wait for it to recharge.
10. The timer has a reset button labeled “RST” in the lower left corner that it may use to silence the beeper and start the countdown again.
11. Several tests, specimen conditioning, observations, and other data, as required by applicable standards, should be recorded and evaluated.

Preparation Before Operation of Glow-Wire Tester

1. To avoid any mishaps, please read and follow the directions before using. It would benefit if you did not use anything but factory-issued parts and accessories.
2. After conducting the glow wire test, it must move the equipment to a room with degreasing ventilation equipment (or to a small laboratory with a dedicated ventilation hood), so it may release the exhaust gases safely.
3. Copper wires pass through holes on the left side of the bracket and hold two matching weights below the bracket plate via two pulleys (connected to the sample bracket).
4. Loosen the nut that keeps the proximity switch in place so it may move left and right, and then mount the sample by the criteria of the test standard and the proximity switch adjustment.
5. Just hit the “Left Button,” and the vehicle will start driving leftwards. To stop the vehicle when the sample is placed on the hot wire, manually toggle the proximity switch.
6. To adjust the current regulating knob, press the “Heating” button. See whether the temperature is within range for the test by adjusting the current to a value that works with your sample.
7. Glow wire testing equipment has a limit electromagnet that is deactivated when the test sample reaches the hot wire head, allowing the 1 N weight to draw forward just 7 mm.
8. After the experiment is complete, the heating button will appear and turn the current knob clockwise to its lowest setting.

It’s not simple to get reproducible results with this test, just as it is with other flammability tests. LISUN developed a glow wire test apparatus to ensure consistent results and user-friendliness. The improvements used to accomplish these objectives are shown in bold below.

Features

1. The carriage carrying the specimen is moved forward and backward by a motor, and the whole process is fully automated.
2. Because it’s dual speed, you can alter the speed at which it travels at either end. In addition, the pace of the approach slows down shortly before making contact (adjustable position of speed reduction).
3. Its remote-control capabilities may be used within a test chamber (T1-14 or similar) to keep the environment safe and steady.
4. A timer begins counting down as soon as the sample touches the wire loop and reverses the carriage’s motion once a predetermined amount of time has elapsed (30 seconds).
5. By switching the temperature controller to manual mode, a steady voltage signal may be sent to the glow-wire throughout testing, protecting the sample from fluctuations in output power that would otherwise be transmitted back from the control thermocouple.
6. It may easily clean off burnt plastic and other residues on the mirror-polished stainless surface on which the wooden board with wrapping tissue has been placed.
7. The apparatus examines the raw materials and completed components for fire-resistant qualities.
8. A temperature programmer is used to establish and regulate the glow-starting wire’s temperature.
9. A perforated stainless steel specimen support is installed on the carriage for easy access and accurate sample placement (4 adjustments).
10. A very accurate flame height measurement scale.
11. The front panel is anodized aluminum with component labels that spell out their intended uses.

Main applications of glow wire tester
IEC 60335-2 is an international standard that mandates the safe operation of household appliances. The non-metallic materials used to support the current-carrying components of the appliance are put through a glow wire test to see whether they catch fire, as required by the standard.
The intensity of the glow wire test mandated by IEC 60335-1 is affected by whether or not the appliance is being monitored during operation and by how much current flows through the connection.
Vacuum cleaners, irons, and coffee makers are all examples of attended appliances that need regular monitoring. Kitchen, laundry, and dishwashing appliances are all examples of “unattended” devices since they may be left in place and operate with little human interaction.
Connectors in unsupervised applications that transfer more than 0.2A of current undergo the strictest testing. To fulfill this requirement, three levels of flammability testing must be performed:

1. To go on to the next round of testing, the material’s GWFI must be more than 850 degrees Celsius, OR the completed product must pass the glow wire test at 850 degrees Celsius.
   The accompanying statement emphasizes the importance of the sample extinguishing itself within 30 seconds. It will conduct the evaluations by procedure 6095-2-11.

2. To proceed to the next testing process, the material’s GWIT must be at least 775 degrees Celsius, or the completed product must pass the glow wire test at 750 degrees Celsius.
   During final product testing, it is crucial that any sparks fade out after two seconds on their own, or else it must apply the third level of quality control to the surrounding components.

3. The third and final level of inspection (conducted only if the connection displays a flame for more than 2 seconds) is not conducted on the connector itself but any appliance components inside a notional envelope above the connector.

Only contents of the envelope made from materials with a UL746A minimum flammability classification need to be checked. A needle flame test is conducted if there are parts within the package that isn’t UL746A.

Conclusion
Glow wires for home appliances are regulated by the international standard IEC 60335-2. However, the IEC 60695-2 standards document may provide the precise method and procedure for testing glow wires.
The glow wire test apparatus evaluates our light fixtures’ fire and ignition resistance. Our products will meet all your heating needs. All our light fixtures are made with highly combustible polymers.

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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