The Danger of Voltage Sags & Swells

Voltage sags and swells are common in most industrial settings and don’t often cause a complete loss of power. However, they can create major power quality issues and potentially damage or shut down sensitive equipment. PMC offers a number of different ways to monitor power quality so you can determine whether power is sagging, swelling or dropping out.

Voltage sags are brief reductions in voltage, typically lasting from a cycle to a second, or tens of milliseconds to hundreds of milliseconds. Voltage swells are brief increases in voltage over the same time range.

Sags are most often caused by abrupt increases in loads such as short circuits or faults, motors starting, or electric heaters turning on, or they are caused by abrupt increases in source impedance, typically caused by a loose connection. Voltage swells are almost always caused by an abrupt reduction in load on a circuit with a poor or damaged voltage regulator, although they can also be caused by a damaged or loose neutral connection.

Knowing that you have periods of transient power and being able to isolate the cause is critical to maintaining power quality, and maintaining equipment and production up-time. If you think you’re having power quality issues, PMC recommends renting or buying a power analyzer like the Dranetz HDPQ, or the Dent Elite pro to check for sags or swells.

Or, if you need a solution that provides 24/7 monitoring, the Dent Power Scout may be used as well.  We also sell protective relays made by Crompton instruments that can detect under voltage situations in both three phase and single phase power environments.

Contact us to learn what option would be best for you.

2017-02-13T10:10:17-06:00February 9th, 2017|