Power Quality Analyzer for Sags, Swells, Transients.

Renewable energy power generators are a continue target of swells, sags and transient voltage spikes from loads and utility power. All of this are filtered by invertors and synchronized with the utility power grid for a seamless energy transfer. Power Quality defines conditions that allow electrical system in such a situation to operate reliably.

Sags – represents a low voltage condition. Voltage sags are momentary and last from a few cycles to minutes, or in unusual case of a “brownout” last for hours.  A sag is referred to as a “dip”. If the voltage dips below 90% for more than one minute many technical committees describe this situation specifically as an under voltage or sometimes brownage. Effects of voltage sags:  All electric machines and appliances must have an adequate voltage source.  If the voltage falls below a certain limit, usually specified by the manufacturer, the machine or appliance will shut down and turn off, or become damaged.

Swells – it is opposite to a low voltage condition and occurs when voltage is suddenly increased. Voltage swells are often momentary and usually last just a few cycles to minutes. Similar to sags, technical committees define swells as when the RMS voltage exceeds the nominal voltage by 10 to 80% for 0.5 cycle to 1 minute. Effects of voltage sags: When the voltage rises above a certain limit (usually specified by the equipment manufacturer) electrical equipment, machines, and appliances can malfunction, shut down and turn off, or become damaged.

Transients – these are very short duration bursts of energy on the power line that show up as brief, fast-rising voltage excursions on the sine wave.  You also may see the terms: “spike”, “impulses” or “surge” being used to describe these phenomena. They typically last for a few microseconds to several milliseconds and are caused by loads turning on or off. Most electrical devices will either require an inrush of energy to charge them when power is first applied, and conversely will discharge some stored energy when turned off.