Harmonics in electrical power systems refer to currents or voltages with frequencies that are integer multiples of the fundamental power frequency, which in the US is 60 Hertz. Harmonics are produced by non-linear loads such as semiconductor devices like transistors, IGBTs, MOSFETS, diodes, and common office equipment such as computers, printers, fluorescent lighting, battery chargers, and variable-speed drives). Harmonics can cause issues such as overheated transformers, tripped breakers, and increased current in the system, particularly for the third harmonic, which causes a sharp increase in the zero sequence current and therefore increases the current in the neutral conductor). Harmonics can also cause distortion and deviation from sinusoidal waveforms in current and voltage. Electric motors do not normally contribute significantly to harmonic generation). Harmonics can be mitigated through the use of harmonic filters, which are designed to reduce the harmonic content of the electrical system.