Factors To Consider When Selecting Neutral Blocks - Power Processing Capability
When selecting neutral blocks, power processing capability is one of the core considerations, which needs to be evaluated comprehensively from the following aspects:
1. Load matching
Ensure that the rated current value of the terminal is higher than the maximum operating current of the equipment. According to the formula P=U × I, power (P) is proportional to current (I), and high-power equipment will inevitably generate greater current. For example, a 3kW device with a current of 13.6A at 220V voltage requires the selection of terminals with a current carrying capacity of ≥ 15A. In industrial scenarios, high load equipment such as motors and frequency converters require copper or special alloy terminals to reduce heat generation by utilizing their excellent conductivity.
2. Temperature rise control
Long term high load operation can cause temperature rise due to terminal contact resistance. It is necessary to select products with optimized contact surface design (such as nut press wire type with tighter contact than spring type), and calculate whether the actual working current exceeds the terminal temperature rise limit (usually required to be ≤ 60 ℃). For environments with poor heat dissipation such as enclosed control cabinets, it is recommended to reduce the power rating by 20% -30%.
3. Material adaptability
Copper terminals have better conductivity than aluminum, but they are more expensive. Aluminum conductor equipment should use copper aluminum transition terminals to avoid electrochemical corrosion. Silver/tin plating surface treatment can improve conductivity and is suitable for scenarios such as high-frequency switching power supplies. Ceramic or fiberglass reinforced flame-retardant material terminals should be selected for high-temperature environments (such as lighting fixtures).
4. Environmental protection level
In humid and corrosive environments (such as seaside equipment), terminals with a protection level of IP65 or above should be selected, or waterproof connectors should be used. Vibration scenarios (such as in car equipment) require the use of anti loosening nuts or terminals with locking functions to prevent local overheating caused by poor contact.
5. Standard compliance
Must comply with standards such as IEC 60947 and GB/T 14048, with a focus on power test reports from certification bodies such as UL and VDE. In the field of new energy (such as photovoltaic inverters), additional special requirements such as salt spray resistance and UV resistance need to be met.
Selection suggestion: Establish a list of equipment power, calculate the maximum current value of each circuit, and select terminal specifications with a 30% margin based on the ambient temperature (estimated to decrease the current carrying capacity by 5% for every 10 ℃ increase). It is recommended to conduct infrared temperature measurement verification for key equipment to ensure full lifecycle reliability.
