What effect do harmonics typically have on electrical systems?

Harmonics in electrical systems are generally considered detrimental, and they can indeed have multiple adverse effects. When harmonics are present, they can lead to an overall reduction in system efficiency because they cause additional losses in equipment such as transformers, motors, and generators. These losses occur due to the distortion of the current waveform, leading to less effective use of power.

Additionally, harmonics can increase reactive power losses, which further contributes to inefficiencies within the system. Reactive power is the power that oscillates between the source and the load, and when harmonics are present, this can cause higher current flows, resulting in greater losses in resistive elements of the system due to the I²R losses, where I is current and R is resistance.

Harmonics can also reduce system voltage by causing voltage drops across components like transformers and transmission lines, leading to voltage regulation problems. These voltage fluctuations can negatively impact the performance of sensitive electronic equipment that relies on stable voltage levels.

Overall, harmonics manifest in several ways that decrease system efficiency, increase reactive power losses, and potentially reduce system voltage, making "all of the above" the most comprehensive answer that encompasses the various impacts of harmonics on electrical systems.