In a scenario where a 300 KVA transformer delivers power to a 180-amp 3Ø load, what must the primary line conductors be sized to carry at least?

To determine the necessary size of the primary line conductors for a transformer delivering power to a three-phase load, it is important to consider the power ratings and the load current. In this scenario, the transformer is rated at 300 KVA and is supplying a 180-amp three-phase load.

First, we need to convert the load current into a corresponding KVA rating. The formula to determine the KVA from current is:

[

KVA = \sqrt{3} \times Voltage \times Current

]

In a typical three-phase system, if the load current is 180 amps, assuming a standard voltage of 480V (which is common in industrial systems), the KVA calculation would be:

[

KVA = \sqrt{3} \times 480V \times 180A \approx 149.7 KVA

]

Since the transformer rating is 300 KVA, it is sufficient for supplying the 180-amp load.

Next, in terms of sizing the primary conductors, the National Electrical Code (NEC) provides guidelines for determining the minimum conductor size based on ampacity and various factors such as load type and continuous vs. non-continuous loads. Conductors need to