What are common power quality issues and their impacts?

Power quality issues include: voltage sags (brief voltage drops causing equipment trips), swells (overvoltages damaging sensitive electronics), harmonics (distorting waveforms, causing heating), transients (fast spikes damaging insulation), flicker (voltage fluctuations causing visible lighting variation), and interruptions (complete loss of power). Sources include motor starting, arc furnaces, variable frequency drives, and switching operations. Solutions include filters, UPS systems, DVRs, and proper grounding.