Certified Energy Manager Practice Exam

Which situation can cause reactive power penalties on an energy bill?

1. Excessive harmonic generation

2. High power factor loads

3. Low load conditions

4. Reactive load compensation

The correct answer is: Excessive harmonic generation

Excessive harmonic generation can cause reactive power penalties on an energy bill because it distorts the voltage waveform, leading to increased reactive power consumption. Harmonics are generated when nonlinear loads, such as computer power supplies and variable frequency drives, draw current in a non-sinusoidal manner. This distortion results in a need for the electrical system to supply additional reactive power to maintain voltage levels, which can be charged by utilities through penalties, especially if the overall power factor exceeds certain limits. In contrast, high power factor loads are generally desirable and can lead to lower charges, as they consume less reactive power. Low load conditions often result in lower overall energy consumption and can sometimes lead to lower charges as well. Reactive load compensation is used to improve power factor and can mitigate penalties rather than cause them.