Journeyman Lineman Practice Test

To determine the kVA of a 3-phase load on an open bank system, it is crucial to understand the relationship between single-phase and three-phase power calculations. In a three-phase system, the total power (kVA) is calculated using the formula:

\[

\text{Power (kVA)} = \sqrt{3} \times \text{Voltage (V)} \times \text{Current (I)}

\]

The value of \(\sqrt{3}\) is approximately 1.732. However, when converting from a kVA figure that represents single-phase power to a kVA figure for a three-phase power application, the kVA should be adjusted based on the type of electrical connection being used.

Since the calculation for the total power consumed in a three-phase system requires multiplying by the square root of three, if you are asking for the effective kVA on an open bank (which tends to use a delta configuration), you would indeed multiply the kVA value by approximately 0.866 to account for the specific conditions of the connection.

This multiplication factor is based on the conversion of an equivalent kVA system from line-to-line current measurements to line-to-neutral measurements, relevant for open delta configurations. Thus,