Insulation Principle Of Terminal Blocks: Key To Ensuring Electrical Safety
As the core component of electrical connections, the insulation principle of terminal blocks is the cornerstone for ensuring the safe operation of electrical systems. It constructs a complete electrical safety protection system through a triple mechanism of physical isolation, material barrier, and structural design.
The physical isolation mechanism is the foundation of the insulation principle. The terminal block adopts an engineering plastic shell to wrap the metal conductive parts, forming the first physical barrier. Taking PA66 (nylon 66) as an example, its melting point reaches 265 ℃, the flame retardant grade is UL94 V0, and it can maintain structural stability in environments ranging from -40 ℃ to 125 ℃. When the wire is inserted into the terminal hole, the insulating shell completely isolates the conductive metal from the external environment, preventing electric shock or foreign object intrusion that may cause a short circuit. In photovoltaic systems, LCP (liquid crystal polymer) material is used for micro terminal manufacturing due to its temperature resistance of 300 ℃, ensuring insulation reliability in high-temperature environments.
The material barrier mechanism is optimized for performance through a special formula. After adding 30% fiberglass reinforcement to modified engineering plastics, the bending modulus was increased to 10 GPa, and the addition of red phosphorus/bromine flame retardants passed UL94 V0 certification. Taking PBT (polybutylene terephthalate) as an example, its hydrolysis resistance makes it the preferred material for outdoor junction boxes, and it can maintain insulation resistance>1000 M Ω in humid environments. For special scenarios such as nuclear power plants, epoxy resin is widely used in the manufacturing of terminal insulation layers due to its anti nuclear radiation properties.
The structural design mechanism enhances the protection level through precision craftsmanship. The H-type through wall terminal block adopts a double-layer insulation structure, with an inner PA66 shell responsible for foundation isolation and an outer silicone sealing ring achieving IP68 protection level. In the field of rail transit, glass fiber reinforced polyamide (PAGF) terminal brackets are controlled by a 0.02mm size to ensure a safe gap with conductive components. After 5000 cycles of insertion and extraction, the insulation layer of the terminal can still remain intact, with a contact resistance of less than 1 m Ω, meeting the requirements of IEC 60947-7 standard.
The insulation principle of terminal blocks runs through every aspect of electrical connection, from material selection to process control. In industrial control scenarios, the combination of PBT shell and silver plated copper alloy can withstand 10g vibration impact; In the field of automotive electronics, PA66+tin plated phosphor bronze terminals can maintain elastic contact at low temperatures of -40 ℃. Behind these technical parameters is the concrete manifestation of the insulation principle's commitment to electrical safety.
