As power and energy systems continue to evolve toward higher power density and enhanced reliability, engineering plastic fasteners have gradually become essential insulating structural components. With proper material selection and reliability validation, plastic screws can not only meet mechanical strength requirements but also provide excellent electrical safety performance.
Part 1: Transformation of Power Equipment Fasteners: Selection Logic from Metal to Engineering
Part 2: Engineering Plastics for Power Applications: From Material Specifications to Typical Uses
Part 3: Case Study: Reliability Evaluation of Engineering Plastics in Transformer Oil Environments
However, when facing high voltages of several kilovolts and complex chemical environments, how should one select the right plastic fastener?
In this article, we will explore the key selection logic from the perspectives of material science and practical data.
- 1. Simplified insulation design:
Eliminates creepage distance requirements and additional insulation spacers required by metal components. (Ref. 1) - 2. Mitigation of EMI sensitivity:
Non-magnetic and non-conductive properties prevent induced currents and eddy current losses in alternating magnetic fields. (Ref. 2) - 3. Corrosion resistance:
For outdoor Energy Storage Systems (ESS), plastics are immune to salt spray corrosion. (Ref. 3)
- 1. Dielectric Strength (ASTM D149):
Maximum voltage a material can withstand before breakdown. Critical for high-voltage insulation points in SST systems. - 2. Volume Resistivity (ASTM D257):
Measures insulation performance under DC electric fields. - 3. Comparative Tracking Index (CTI, IEC 60112):
Indicates resistance to surface tracking under humid or contaminated conditions. - 4. Electromagnetic Compatibility (ASTM D4935 / EMI Shielding Effectiveness):
Evaluates interaction with high frequency electromagnetic fields.
This aligns with Measurlabs' emphasis on polymer electrical stability. In high density power designs, “non-interference” is often more cost-effective than “shielding.”
Professional material selection begins with a deep understanding of material science. After ensuring baseline electrical performance, how should materials be chosen for different application scenarios?
In the next article, we will provide a detailed analysis of engineering plastic materials and their application contexts.
Ref.1: IEC 60664-1: Insulation coordination for equipment within low-voltage systems. This standard explains how insulation material classification (such as CTI – Comparative Tracking Index) can be used to reduce the required distance between conductive parts. According to IEC 60664-1, selecting engineering plastic fasteners with a high CTI rating can effectively reduce creepage distance requirements within power modules, enabling equipment miniaturization.
Ref.2: IEEE Transactions on Power Electronics. In high-frequency alternating magnetic fields, metal screws can form small “short-circuit loops,” generating eddy current losses that lead to localized overheating and electromagnetic radiation interference. As noted in classical literature such as Power Electronics, non-metallic materials can prevent eddy current generation under high-frequency magnetic fields, which is critical for stabilizing EMI-sensitive circuits.
Ref.3: ASTM B117: Standard Practice for Operating Salt Spray (Fog) Apparatus. Engineering plastics (such as PPS and PVDF) possess inherent chemical inertness and can pass rigorous salt spray testing without the need for additional plating. For outdoor energy storage systems (ESS), selecting polymer materials with excellent chemical resistance eliminates the oxidation and corrosion risks commonly observed in metal components under ASTM B117 testing conditions.
Ref.4: Electrical Testing of Plastics and Polymers – Measurlabs, Ryan Johnsson, MSc in Polymer Chemistry
Ref.5: Electrical Properties Standards: Evaluation of dielectric loss and dielectric constant is referenced to ASTM D150 (covering frequencies from power frequency up to the megahertz range) and other relevant high-frequency testing standards.
Ref.6: Data source and experimental basis: The data presented are derived from our company’s internal laboratory reports for power and energy equipment development. Test method: Based on the principles of ASTM D543 (Standard Practices for Evaluating the Resistance of Plastics to Chemical Reagents), an accelerated high-temperature oil immersion test was conducted. Test conditions: Screws were fully immersed in transformer insulating oil at an ambient temperature of 120°C for a duration of 4 hours.
