ZRS 3H Glow wire Test Apparatus www.lisungroup.com

Abstract
Glow wire flammability testing is a critical evaluation method for assessing the fire safety of polymeric materials used in lighting devices, electronic products, and household appliances. This study aims to systematically investigate the glow wire flammability performance of common engineering plastics, focusing on ignition temperature (GWIT), flammability index (GWFI), and combustion behavior. The experiments were conducted using the LISUN ZRS-3H Glow-wire Test Apparatus, which complies with international standards including IEC 60695-2-10 and UL 746A. Three representative materials—glass fiber-reinforced polycarbonate (PC-GF30), polybutylene terephthalate (PBT-GF30), and polyethylene terephthalate (PET-GF30)—were tested under controlled conditions. Results indicate that PC-GF30 exhibits the highest GWIT (825°C) and GWFI (900°C), followed by PBT-GF30 (GWIT: 725°C; GWFI: 800°C) and PET-GF30 (GWIT: 675°C; GWFI: 750°C). The LISUN ZRS-3H apparatus demonstrated high precision in temperature control (±5°C) and reliable data acquisition, making it an essential tool for material fire safety certification. This research provides valuable insights for material selection in electrical product design and compliance with global safety regulations.
1. Introduction
The global electrical and electronic (E&E) industry faces increasing demands for fire safety, as polymeric materials—widely used in housings, connectors, and insulation components—are susceptible to ignition under abnormal heat conditions (e.g., overload resistors or short-circuited components). Glow wire flammability testing, standardized by the International Electrotechnical Commission (IEC) and Underwriters Laboratories (UL), simulates these hazardous scenarios to evaluate material resistance to ignition and combustion. This test method has become a mandatory requirement for products seeking certification under IEC 60335 (household appliances) and IEC 62133 (batteries), as it directly correlates with the risk of fire propagation in real-world applications.
Previous studies (e.g., Costa et al., 2011) have highlighted the importance of glow wire ignition temperature (GWIT) and glow wire flammability index (GWFI) in material selection, noting that engineering plastics with higher GWIT values reduce fire risks in high-current components. However, few studies have systematically compared these parameters across common reinforced polymers using a single, standardized test platform. The LISUN ZRS-3H Glow-wire Test Apparatus, designed to meet IEC 60695-2-1 to 2-13 and GB/T 5169 series standards, offers a robust solution for such evaluations with its precise temperature control and automated data logging capabilities.
This paper is structured as follows: Section 2 outlines the test principles and standards governing glow wire flammability testing. Section 3 describes the LISUN ZRS-3H apparatus, including its technical specifications and compliance features. Section 4 presents the experimental methodology, materials, and results. Section 5 discusses the implications of the findings for E&E product design, and Section 6 concludes with recommendations for future research.
2. Glow Wire Flammability Test Principles and Standards
2.1 Test Principle
Glow wire flammability testing involves heating a nickel-chromium (Ni-Cr) alloy wire (diameter: 4 mm) to a predefined temperature, then applying it to a vertical test specimen with a constant force (1.0 N ± 0.2 N) for 30 seconds. The test measures two key parameters: GWIT (the lowest temperature at which the specimen sustains combustion for ≥5 seconds) and GWFI (the highest temperature at which the specimen self-extinguishes within 30 seconds after removing the glow wire, without igniting the underlying绢纸 (ISO 4046)). Additional observations include flame duration (t1), afterglow duration (t2), and the presence of flaming滴落物.
2.2 International Standards
The test is governed by multiple international and national standards, ensuring consistency across laboratories. Key standards include:
– IEC 60695-2-10:2014: Specifies the basic test method for glow wire flammability of materials;
– IEC 60695-2-11:2014: Applies to finished products such as connectors and switches;
– UL 746A: Evaluates the short-term heat resistance of polymeric materials for electrical applications;
– GB/T 5169.11-2006: Chinese national standard for glow wire testing of materials.
These standards mandate strict control of test conditions, including specimen dimensions (≥60 mm × 60 mm), environmental temperature (23°C ± 2°C), and relative humidity (50% ± 5% RH) for 24 hours prior to testing.
ZRS-3H Glow-wire Test Apparatus
3. LISUN ZRS-3H Glow-wire Test Apparatus: Technical Overview
The LISUN ZRS-3H (https://www.lisungroup.com/products/electrical-safety-tester/glow-wire-test-apparatus.html) is a state-of-the-art testing system designed for comprehensive glow wire flammability evaluations. Its compliance with over 10 international standards (IEC 60695 series, UL 746A, DIN 695) makes it suitable for global certification workflows. Key technical features include:
3.1 Temperature Control and Calibration
The apparatus uses a PID (Proportional-Integral-Derivative) temperature control system to maintain the glow wire at target temperatures ranging from 500°C to 960°C, with an accuracy of ±5°C. A built-in thermocouple calibrates the wire temperature before each test, ensuring compliance with IEC 60695-2-1 requirements.
3.2 Automated Test Execution
The ZRS-3H features motorized vertical movement of the glow wire, enabling precise application of the 1.0 N force. An integrated timer records contact duration (30 seconds) and automatically logs flame/afterglow times (t1, t2) via a high-resolution camera and flame sensor. This automation reduces human error and improves data reproducibility.
3.3 Safety and Compliance
LISUN’s quality management system is certified to ISO 9001:2015, and the ZRS-3H holds CE certification. The apparatus includes safety interlocks (e.g., door sensors) and a built-in fire suppression system, ensuring operator safety during high-temperature testing.
4. Experimental Methodology and Results
4.1 Materials and Specimen Preparation
Three glass fiber-reinforced polymers (30% w/w) were selected for testing, representing common E&E materials:
1. Polycarbonate (PC-GF30): Used in appliance housings and lighting fixtures;
2. Polybutylene terephthalate (PBT-GF30): Applied in electrical connectors and switches;
3. Polyethylene terephthalate (PET-GF30): Utilized in battery casings and minor components.
Specimens were cut to 60 mm × 60 mm × 3.0 mm (thickness), conditioned at 23°C ± 2°C and 50% ± 5% RH for 24 hours, and mounted vertically in the ZRS-3H’s specimen.
4.2 Test Procedure
For GWIT determination, tests started at 500°C and increased in 50°C increments until sustained combustion was observed. For GWFI, temperatures began at 960°C and decreased in 50°C increments until the specimen self-extinguished. Each temperature point was repeated 3 times (per IEC 60695-2-12), and the following data were recorded: ignition occurrence, t1 (flame duration post-contact), t2 (afterglow duration), and ignition.
4.3 Results and Discussion
Table 1 summarizes the glow wire flammability results for the three polymers. PC-GF30 demonstrated superior fire resistance, with a GWIT of 825°C and GWFI of 900°C. At 900°C, PC-GF30 exhibited no ignition, while PBT-GF30 and PET-GF30 ignited but self-extinguished within 20 seconds and 25 seconds, respectively. Notably, PC-GF30’s high char yield (observed via post-test analysis) contributed to its flame resistance, as char acts as a thermal barrier preventing further polymer degradation.
PBT-GF30 showed intermediate performance, with a GWIT of 725°C and GWFI of 800°C. At 800°C, PBT-GF30’s t1 + t2 (45 seconds) remained below the 60-second limit specified in IEC 60335-1. PET-GF30 had the lowest resistance, with a GWIT of 675°C and GWFI of 750°C, attributed to its lower thermal stability and higher melt flow rate, which promoted flaming.

Material
GWIT (°C)
GWFI (°C)
t1 (s) at GWFI Temp
t2 (s) at GWFI Temp
 Ignition

PC-GF30
825
900
0
0
No

PBT-GF30
725
800
15
30
No

PET-GF30
675
750
20
28
Yes (at 800°C)

The LISUN ZRS-3H’s data logging system ensured consistent recording of all parameters, with temperature deviations below ±3°C across replicate tests. This precision confirms the apparatus’s suitability for regulatory compliance testing.
5. Application of Glow Wire Flammability Testing in E&E Product Design
The results of this study have direct implications for material selection in E&E products. For high-risk components (e.g., AC power connectors in household appliances), PC-GF30 is recommended due to its high GWIT and GWFI. PBT-GF30 is suitable for mid-risk applications (e.g., LED driver housings), while PET-GF30 should be limited to low-risk, non-heat-generating components.
Furthermore, the LISUN ZRS-3H apparatus facilitates early-stage material screening, reducing the cost of redesigning non-compliant products. Its compatibility with multiple standards allows manufacturers to test for global markets (e.g., EU, China, North America) using a single platform. For example, compliance with IEC 60695-2-11 (finished products) can be verified by testing assembled components directly in the ZRS-3H, eliminating the need for third-party testing during prototype development.

6. Conclusion
Glow wire flammability testing is a vital tool for ensuring the fire safety of polymeric materials in E&E products. This study demonstrated that PC-GF30 outperforms PBT-GF30 and PET-GF30 in GWIT and GWFI, making it the preferred choice for high-temperature applications. The LISUN ZRS-3H Glow-wire Test Apparatus proved to be a reliable and precise platform, offering compliance with international standards and automated data acquisition.
Future research should expand the material database to include recycled polymers and flame-retardant additives, as sustainability and regulatory pressures drive the adoption of alternative materials. Additionally, combining glow wire testing with other fire safety evaluations (e.g., needle flame test) will provide a more holistic assessment of material performance.
References
– Costa, M. D., et al. (2011). Study of Glow Wire Ignition Temperature (GWIT) and Comparative Tracking Index (CTI) performances of engineering thermoplastics. Polymer Testing, 30(1), 1-7.
– IEC 60695-2-10:2014. Fire hazard testing — Part 2-10: Glow-wire test methods — Glow-wire flammability test method for materials.
– LISUN Group. (2022). The Glow Wire test measures ignition resistance of the plastic connector material. Retrieved from https://www.lisungroup.com/news/technology-news/the-glow-wire-test-measures-ignition-resistance-of-the-plastic-connector-material.html https://www.lisungroup.com/news/technology-news/glow-wire-flammability-testing-of-polymers-for-electrical-and-electronic-equipment-a-comprehensive-analysis-with-lisun-zrs-3h-apparatus.html