WHAT ARE VOLTAGE SAGS (DIPS) AND SWELLS?

Voltage sags (also known as voltage dips) and swells are the most common types of power quality disturbances. Every electrical system or equipment is designed to work at a specific voltage rating. Changes in voltage below or above a user- defined low/high limit might damage the electronic/industrial equipment, cause outages and other power quality issues.

WHAT ARE VOLTAGE SAGS (DIPS)?

A voltage sag (dip) is a brief reduction in RMS voltage of 10% or more below the recommended range for a period of 1/2 cycle to 1min as defined in the IEC 61000-4-30 standard. The cause of it is a sudden large change of loads through the source impedance such as in a motor startup or a short circuit events. Voltage sags (dips) are a common power quality event that can occur several times per year at a typical industrial sites PCC and even more at the equipment terminals. In recent years, it is required that electrical equipment has the ability to ride through brief voltage sag events. The requirement depends on the sag characteristics and the application.

WHAT ARE VOLTAGE SWELLS?

Voltage swells are the opposite of voltage sags (dips) and they are defined as a momentary increase in RMS voltage of 10% or more above equipment recommended voltage range for a period of 1/2 cycle to 1 min, as defined in the IEC 61000-4-30 standard.
Voltage swells are less common than voltage sags (dips) and they are usually related to system fault conditions. Swells can occurs as a result of a single line to ground fault, which will briefly raise the voltage level of the un-faulted phases as shown in the example below. This is more likely to happen in an ungrounded or floating ground delta systems. Swells can also occur when a large load is turned OFF.

SOLVE POWER QUALITY EVENTS AND REDUCE THEIR FREQUENCY WITH ADVANCED PQ ANALYZERS

In order to solve these events and reduce their frequency, you need a power quality analyzer that gives you accurate monitoring and analyzation process. Elspec PQ analyzers with the PQZIP technology give you:
• Continues waveform recording
• Easy view and simple graphs.

Elspec G4400 PQ analyzer

OVERCOMING POWER DISTURBANCES CHALLENGES

In order to solve these events and reduce their frequency, a monitoring and analyzing process is required. The recent IEEE 1668 standard Recommended Practice for Voltage Sag and Short Interruption Ride-Through Testing for End-Use Electrical Equipment Rated Less than 1000V draws the lines for dealing with this kind of events. This allows software packages, such as Sapphire, the ability to translate the data to an easy view and simple graphs. Using this kind of software, combined with power quality meters/power quality analyzers for measurement, enables to gather a full record of voltage dips, swells and other power disturbances.

A power quality analyzer with a continuous waveform recording will capture almost any event in your network without the need to set triggers or thresholds manually to capture events. This advanced analyzer will enable you easy deployment and the ability to connect the event to a specific state to figure the cause of the problem. Defining magnitudes and durations of sags that should not result in equipment failure, for example, and the ability to tell the severity of the sag history on the facility will improve, by default, the stability and reliability of your system/equipment.

Elspec offers a comprehensive solution for measurement, analyzation and power factor correction, all in one place. Our power quality meters and analyzers equipped with our continuous waveform recording technology (of up to 1024 samples/cycle), will bring you highly accurate results. Elspec PQSCADA Sapphire software will provide you fast performance and full functionality for data exploration, analysis and visualization as your advanced single and unified source for multiple power quality disturbances and way more. Read more about Elspec PQSCADA Sapphire software here.

Finally, our wide range of transient-free power quality solutions will help you reduce power disturbances and improve production quality. From a real time reactive power compensation Equalizer through a transient free power factor correction Activar or a centralized motor startup solution, we will provide you the best power quality solution tailored for your needs.