Apprentice Lineman General Practice Test

To determine the primary amps for a 50 kVA transformer operating at a primary voltage of 12,470 volts, the relationship between power, voltage, and current can be applied. The formula used to calculate current (in amps) is derived from the power formula:

\[ \text{Power (kVA)} = \text{Voltage (V)} \times \text{Current (I)} \]

This can be rearranged to find current:

\[ \text{Current (I)} = \frac{\text{Power (kVA)} \times 1000}{\text{Voltage (V)}} \]

In this case, the power is 50 kVA, which translates to 50,000 watts (since 1 kVA = 1000 VA), and the voltage is 12,470 volts. Plugging these values into the formula gives:

\[ \text{Current (I)} = \frac{50,000}{12,470} \approx 4.0 \text{ amps} \]

This calculation shows that at a primary voltage of 12,470 volts, a 50 kVA transformer would indeed have approximately 4.0 amps of primary current. Therefore, this option is supported by