Swells and overvoltages are basically the opposite of sags and undervoltages. A swell is an increase in voltage lasting up to one minute, and an overvoltage is the long-term effect of a swell. These situations happen when available voltage is higher than the demand. It normally starts when there is a huge demand for power. Due to this, utility companies normally increase voltage to meet the demand. When the demand goes down rapidly, there is the possibility that the voltage will remain high causing the swell or overvoltage.
These power problems normally affect rural areas since utility companies usually leave voltage at a high level over the weekend even after the demand has gone down. These situations also happen when the system voltage regulator is inefficient, or when the transformer settings are not set properly by the power company.
Even when overvoltages are brief, they can be damaging to equipment. These power problems can cause equipment to overheat and damage them. They may also cause lights and monitors to flicker. Data centers are susceptible to these situations since they may cause data errors in computer systems. Semiconductors may also be damaged by overvoltages and swells.
To prevent swells and overvoltages from affecting sensitive equipment, it is necessary to use an uninterruptible power supply or UPS system. While the most basic protection against this power problem is a standby UPS system, the best way to protect equipment from a swell or overvoltage is by using an online UPS. These devices protect equipment from sudden increases in voltage. They automatically adjust voltage in case these power problems occur to ensure electricity-powered equipment are protected.