Powersight

A voltage sag lasts less than a second. A swell might last even less. Yet either one can trip a drive, corrupt a batch process, or quietly shorten the life of sensitive equipment, and most facility teams never see it happen. That is the problem with power quality events. They come and go faster than anyone is watching. By the time equipment fails or a process resets, the disturbance that caused it is long gone, unless something was recording at the moment it happened. This guide breaks down what sags and swells actually are, what causes each one, and how sag and swell detection through a power event recorder lets you catch the evidence instead of guessing after the fact. What Counts as a Voltage Sag or Swell? The IEEE gives these events precise definitions, and the numbers matter. According to IEEE Standard 1159-2019 , a voltage sag is a decrease in RMS voltage to between 0.1 and 0.9 per unit of nominal voltage, lasting anywhere from half a cycle to one minute. A voltage swell works th...

  Pull out your last commercial electric bill and find the line item labeled "demand charge." For most facility managers, that single number is bigger than they expect, and harder to control than they'd like. According to the National Renewable Energy Laboratory (NREL) , demand charges can represent 30% to 70% of a commercial customer's total electricity bill, depending on the rate structure and how the building actually uses power. That means a single 15-minute spike, one bad afternoon where everything runs at once, can set your cost for the entire month. This is where building power monitoring earns its keep. It's not just about tracking total energy use. It's about seeing exactly when, where, and why your building hits its peaks, so you can do something about it before the bill arrives. Why Demand Charges Deserve Your Attention Total consumption tells you how much energy your building used. Demand tells the utility how hard your building hit the grid at its...