The calculation process for selecting the size of cables based on capacity and power consumption
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I’m asking the expert here how to calculate this. No need for any mnemonics; I want to see the calculation process. Could you please provide a detailed explanation?:) :D
For three-phase motors, estimate the current required as 2A per 1kW, and then use a table to select the appropriate cable. For single-phase motors, calculate the current using P=0.8*220*i, and then select the cable by referring to a table.
First, the current-carrying capacity must be satisfied; secondly, it is necessary to check whether the voltage drop is within acceptable limits based on the cable length; thirdly, it is required to determine whether the circuit breaker can interrupt the circuit in the event of a ground fault, based on the cable length (when using the circuit breaker’s instantaneous tripping function for ground fault protection). The third condition becomes difficult to meet when the power supply distance exceeds 150 meters, and other measures must be employed as ground fault protection.