Purchasing Neutral Blocks: Pay Attention To These Key Technical Indicators
When purchasing neutral blocks, it is important to focus on the following key technical indicators to ensure product performance, safety, and long-term stability, and to avoid electrical failures or safety hazards caused by improper selection.
1. Rated current and voltage
The rated current is the maximum continuous current carried by the terminal, which needs to be calculated based on the circuit load and reserved with a margin of 20% -30%. For example, 10A circuits should choose 12-15A terminals. The rated voltage should match the system voltage, such as selecting 500V for low-voltage circuits and 1000V or above terminals for high-voltage systems to prevent arc breakdown.
2. Contact resistance and temperature rise
Contact resistance directly affects electrical energy loss and heat generation. The contact resistance of high-quality terminals should be less than 50m Ω, and the temperature rise during long-term operation should not exceed 45K (ambient temperature+45 ℃). Excessive temperature rise can accelerate the aging of insulation materials and even cause fires, so low resistance coating terminals such as tin plating and silver plating should be prioritized.
3. Insulation materials and voltage resistance performance
The insulation material needs to pass UL94 V-0 flame retardant certification, and the temperature resistance level needs to adapt to the ambient temperature (such as -40 ℃ to+125 ℃). The withstand voltage test value should be higher than twice the system voltage. For example, a 1500V withstand voltage terminal should be selected for a 220V circuit to prevent insulation breakdown and short circuit.
4. Mechanical strength and plug-in life
The terminal needs to withstand wire tension (such as 10N-50N) and vibration impact, and the insertion and extraction force should meet the standard (such as 2-8N). The insertion and removal lifespan should be over 500 times to ensure reliable contact during frequent disassembly and assembly. Spring type terminals need to check the pressure attenuation rate of the spring plate, and stainless steel or beryllium copper materials should be preferred.
5. Protection level and installation method
Outdoor or humid environments require terminals with a protection level of IP65 or higher to prevent dust and moisture from entering. The installation method should match the equipment structure, such as rail type, screw type, or spring clip type, and confirm dimensional compatibility (such as 35mm DIN rail).
Procurement suggestion: Priority should be given to products certified by IEC 60998, GB/T 14048, etc. Suppliers are required to provide testing reports and verify actual performance through small-scale trials.
