NERC Electric Power Research Institute (EPRI) Practice Exam

To understand the impact of doubling the voltage on power losses in the electric system, consider how power losses are calculated. Power losses in electrical systems, particularly in conductors, are primarily due to the resistance within the wire. These losses can be expressed using the formula:

\[ P_{\text{loss}} = I^2 \cdot R \]

where \( P_{\text{loss}} \) is the power loss, \( I \) is the current flowing through the conductor, and \( R \) is the resistance of the conductor.

When the voltage supplied to a load is doubled, if we maintain the same power consumption, the current flowing through the circuit is impacted because power \( P \) is defined as the product of voltage \( V \) and current \( I \):

\[ P = V \cdot I \]

If the voltage is doubled and power remains constant, the current must adjust to accommodate this change. Specifically, if the voltage doubles (from 120 volts to 240 volts), the current halves. This is because:

\[ I = \frac{P}{V} \]

So if you double \( V \) and keep \( P \) constant, then:

- Original current \( I_1 = \