Question

Scenario 220.23 A closed-delta bank of transformers delivers 120/240-volt power to several loads. The 1-phase loads are drawing 120 amps on AO and 120 amps on CO. The bank is also supplying power to a 30 load that draws 46 amps.

Refer to Scenario 220.23. The approximate calculated size required for the lighting transformer(s) has a rating of ___KVA.

A. 69
B. 40
C. 26
D. 16
E. 48 7.

Answer 1

The approximate calculated size required for the lighting transformer(s) in a closed-delta bank of transformers is 69 KVA.

Step-by-step explanation:

In a closed-delta bank of transformers, the size required for the lighting transformer(s) can be calculated using the formula KVA = Line Voltage x Line Current x √3, where Line Voltage is the voltage supplied by the bank and Line Current is the total current flowing through the bank.

In this scenario, the Line Voltage is 120 V, and the Line Current can be calculated by adding the currents drawn by the 1-phase loads and the load connected to the bank, which gives a total current of 386 A.

Substituting these values into the formula, the approximate calculated size required for the lighting transformer(s) is 69 KVA. Therefore, the correct answer is A. 69.