Glow-wire test apparatus

I. Introduction to the Glow-Wire Test Apparatus

The glow-wire test apparatus is a device used to simulate the glowing elements that electrical products may encounter during operation, in order to evaluate the product's resistance to heat sources. It heats a specific-shaped glow wire to a predetermined temperature and brings it into contact with or close to the test sample, observing the sample's combustion, melting, or other reactions to assess the product's thermal safety.

II. Key Components of the Glow-Wire Test Apparatus

1. Glow-Wire U-Shaped Head

The glow-wire test apparatus is equipped with a Ni/Cr (80/20) glow-wire U-shaped head with a diameter of 4mm ± 0.04mm and a ring shape. The glow wire is heated using a simple electrical circuit, without any feedback devices or feedback loops for temperature maintenance. Due to the presence of high current, it is crucial that the electrical connections of the glow wire ensure the passage of high current without affecting the circuit's performance or long-term stability.

2. Test Temperature System

The temperature at the tip of the glow wire should be measured using a mineral-insulated metal-sheathed fine-wire thermocouple with an insulated junction, with a standard diameter of 1.0mm (new standard). For example, nickel-chromium and nickel-aluminum wires can operate at temperatures up to 960°C, and the sheath should be made of high-temperature-resistant metal capable of operating at 1050°C. The thermocouple is placed in a small drilled hole behind the tip of the glow wire, ensuring a tight fit. The tip of the thermocouple should maintain thermal contact with the bottom of the drilled hole, and care should be taken to ensure that the thermocouple can move as the glow-wire tip expands due to heating.

3. Test Chamber

When operating the glow-wire test apparatus, it should be used under conditions without air currents. A test chamber with a volume of at least 0.5 m³, allowing observation of the test sample, can be used. The chamber's volume should ensure that oxygen depletion during the test does not significantly affect the results. The test sample should be installed at least 100mm away from all surfaces of the test chamber. After each test, air containing decomposition products from the test sample should be expelled from the test chamber.

Technical Parameters:

Compliance Standards: GB/T5169, IEC60695, UL746A, IEC829, DIN695, VDE0471

Dimensions: 1120W*520D*1250H

Glow Wire: Φ4mm Ni/Cr (80/20)

Thermocouple: Φ1.0mm

Heating Temperature: 0–1000°C, continuously adjustable within the range; temperature measurement accuracy ±10°C; capable of continuous operation at 960°C (for 6 hours or more)

Test Sample Pressure: 0.95 ± 0.10N

Sample Movement Speed: 10mm/s–25mm/s (independent forward and backward speeds)

Temperature Application Time: 0.01s–99.99s (adjustable)

Ignition Time: 0.01s–99.99s

Flame Retention Time: 0.01s–99.99s