Tech Talk

The A-B-Cs of Overvoltage

Overvoltage, a power disturbance that occurs when voltage exceeds specified limits, may not be the first potential complication that comes to mind when designing point of sale systems or other applications that encompass electronic equipment. However, understanding what overvoltage is, and implementing technology to guard against is essential.

Overvoltage stems from a number of different factors, including utility switching snafus, construction, falling tree branches, human error and even animals coming into contact with power lines. Overvoltage can lead to multiple electronic equipment problems, from overheating and degradation of hardware to complete component failure. The extent of these problems varies with the duration and the amplitude of the overvoltage itself. However, no equipment—from point of sale hardware and in-store computers, to security equipment and multi-functional copiers, and everything in between—is entirely immune.

 In fact, the destructive after-effects of overvoltage are comparable to those sparked by lightning.  If lightning or overvoltage passes through to electronic equipment, there is an extremely high potential for damage to the power supply unit and other components with direct and/or indirect connections to the power supply. This may require replacement of multiple components at a cost of thousands of dollars.  Additionally, end-users will likely lose their ability to utilize their point of sale and/or other equipment for an extended period of time following an overvoltage incident, negatively impacting overall operations, employee productivity and, in a retail or restaurant environment, sales.

Whatever its source, overvoltage comes in two “flavors”: voltage swell and prolonged/sustained. Voltage swell is caused primarily by a switching of the relays on the power grid outside the building where the equipment is located, or a sudden reduction of the power load inside the building. According to the Institute of Electrical and Electronics Engineers (IEEE) Standard 1159 (“Recommended Practice for Monitoring Electric Power Quality”),  voltage swell is defined as “a temporary increase in RMS voltage that exceeds 110% to 180% of the nominal voltage, with a duration of 0.5 cycle to one minute”.

Meanwhile, a prolonged or sustained overvoltage happens when a loose connection or connection loss occurs on the neutral wire. This is a more dangerous and destructive type of overvoltage that can reach up to 240V and can last for hours until it is resolved by a utility company or electrician. “Sustained” overvoltage can lead not only to a failure of the components in electronic devices, but to a failure of the components in power protection equipment.

Because various types of voltage events may occur multiple times during any given year, retailers, restaurants,  and other businesses would be well-advised to install proper power protection equipment. Such equipment should have a sustained overvoltage protection feature that senses and responses to sustained high voltage conditions, shielding electronic equipment from dangerous, destructive overvoltage incidents. SmartPower Systems’ overvoltage circuit accomplishes this task by detecting prolonged voltage swell. It then disconnects utility power when voltage swell rises above 150V or is sustained for 100 milliseconds. The circuit’s filter allows power to flow once again when the power level returns to normal.