How do terminal blocks ensure their performance doesn't falter under high-voltage, high-current surges?
Publish Time: 2025-12-12
In critical fields such as power systems, industrial automation, new energy equipment, and rail transportation, terminal blocks, though small in size, bear the heavy responsibility of power transmission and signal connection. When a system encounters high-voltage, high-current surges such as startup surges, short-circuit faults, or lightning strikes, improper design or material selection of terminal blocks can easily lead to serious problems such as overheating, arcing, welding defects, or even fire, causing the entire system to fail.
1. Conductive Materials: High Purity and High Stability Combined
The core of terminal blocks is their conductive components, typically made of copper or copper alloys. To cope with high-current surges, high-quality terminals generally use high-purity electrolytic copper, with a conductivity of over 98% IACS, effectively reducing resistance heating. In applications requiring higher strength, tin-phosphor bronze or brass is used, and cold heading or stamping is employed to retain the material's fiber direction, improving mechanical strength and creep resistance. More importantly, these materials must possess excellent thermal stability—they must not significantly soften or oxidize under instantaneous high temperatures, ensuring that contact pressure does not decrease and the connection does not loosen.
2. Contact Structure Design: Balancing Low Impedance and High Clamping Force
Good electrical connections depend not only on materials but also on the design of the contact interface. High-performance terminals commonly employ spring-loaded, screw-loaded, or push-in crimping structures to ensure a sufficiently large contact area and positive pressure between the wire and the terminal. For example, spring-loaded terminals utilize stainless steel springs to provide constant clamping force, making them less prone to loosening even under vibration or thermal expansion and contraction; while dual-contact designs distribute current through redundant paths, reducing localized temperature rise. Furthermore, the contact surfaces are often plated, and combined with precise geometry, can pierce the oxide film on the wire, achieving direct "metal-to-metal" contact, controlling contact resistance to the milliohm level, and fundamentally suppressing Joule heat accumulation.
3. Surface Plating Technology: A Protective Armor Against Oxidation, Arcing, and Sulfation
Bare copper is easily oxidized in air, forming a high-resistivity film, especially in humid, sulfur-containing environments. Therefore, high-end terminal blocks commonly undergo surface plating treatment on contact areas. Common solutions include tin plating, silver plating, and gold plating. In harsh industrial environments, composite plating, such as a "nickel base + silver surface" structure, is used, utilizing the nickel layer to block substrate diffusion while leveraging the high conductivity of the silver layer. Some products even incorporate nano-coatings or self-healing plating technologies to further enhance corrosion and arc erosion resistance.
4. Insulation and Heat Dissipation Design: Preventing Creepage and Thermal Runaway
High voltage not only tests the conductor but also poses a challenge to the insulating shell. High-quality terminals use high-performance engineering plastics with high CTI, effectively preventing surface creepage and carbonization breakdown under high voltage. Simultaneously, structurally, increasing creepage distance and incorporating isolation ribs or grooves extends the arc path and suppresses flashover. In high-current applications, terminal housings are also designed with heat dissipation fins or ventilation channels to accelerate heat dissipation and prevent plastic deformation or metal annealing due to excessive temperature rise.
Faced with the severe challenges of high voltage and high current, terminal blocks are no longer simple metal connectors, but miniature safety hubs integrating materials science, electrical engineering, and precision manufacturing. From high-purity conductors to intelligent plating, from structural optimization to international certification, every detail safeguards "uninterrupted power supply, no overheating, and no arcing." It is this pursuit of ultimate reliability that makes the small terminal a trustworthy "last centimeter" line of defense for modern electrical systems.
