In a closed-delta transformer bank supplying power to several loads, if the 1-phase loads are drawing 120 amps on AØ and CØ, what is the approximate calculated size required for the "lighting" transformer(s)?

To determine the appropriate size of the "lighting" transformers in a closed-delta transformer bank configuration, it's essential to consider the characteristics of the loads being served. In this scenario, the given information indicates that the single-phase loads are drawing 120 amps on two phases, AØ and CØ.

In a closed-delta system, the total apparent power (in kVA) can be calculated using the formula for three-phase systems:

[

S = \sqrt{3} \times V_{L} \times I_{L}

]

Where:

• ( S ) is the apparent power in VA,

• ( V_{L} ) is the line-to-line voltage,

• ( I_{L} ) is the line current.

Assuming a typical voltage level for a lighting system, for example, 240 volts line-to-line, you can plug in the values:

1. Determine the current drawn:

• Since 120 amps is drawn from each of the two phases, you would consider the power drawn as a function of those two phases.

2. Calculate the total kVA based on the loads:

• The total current flowing in the system from two phases would be considered for the calculation. If