Understanding voltage dips, swells and transients
Electrical and electronic devices are designed to operate at specific voltage levels. Deviations like dips, swells, and transients can disrupt industrial controls and sensitive equipment like computers. Surges, which include swells and transients, are usually more harmful than dips. However, both can lead to equipment failures, outages, and other Power Quality Problems.
What Are Voltage Dips?
Voltage dips, known as "sags," happen when the voltage falls 10% or more below the normal level. For example, a 120V outlet can drop to 90V. These dips often create a ripple effect, impacting multiple devices simultaneously.
A voltage dip is defined by two key parameters:
- Depth (Residual Voltage):
- This refers to the relative deviation from the nominal voltage (Uc).
- It indicates the lowest voltage reached on at least one phase during the dip.
- The residual voltage can fluctuate over time across different phases.
- Duration:
- Typically ranges from a few dozen milliseconds to a few hundred milliseconds.
- Rarely lasts longer than 1 second.
Common Causes:
- Starting large motors.
- Temporary short circuits on power lines.
- Overloaded transformers or undersized conductors (causing prolonged dips known as undervoltage).
Impact: Voltage dips can dim lights, disrupt sensitive equipment, or trip industrial processes.
What Are Voltage Swells?
Voltage swells are surges in voltage of 10% or more above the nominal level. For instance, a 120V system experiencing a rise to 135V or higher.
Common Causes:
- Turning off large loads, such as motors.
- Improper transformer tap settings.
- Renewable Energy sources, like solar panels, feeding into the system.
Overvoltage occurs when sustained voltage increases last over a minute, leading to overheating, equipment damage, and decreased power quality.
What Are Voltage Transients?
Voltage transients are sudden, short-lived bursts of unwanted voltage that can range from a few volts to several thousand volts. These events are brief, lasting microseconds to a few milliseconds, but can be highly destructive.
Common Causes:
- Lightning strikes.
- Switching of capacitor banks or generators.
- Faulty contactors or arcing.
- Sudden release of stored energy in electrical systems.
Differences from Swells: Unlike swells, transients are larger in magnitude but shorter in duration. They often result in damage to equipment or disruption of sensitive processes.
How YT Electric Products Help:
Active Harmonic Filters (AHF):
- Reduce voltage distortions caused by harmonic currents.
- Stabilize voltage during dips and swells by compensating for reactive power.
- Improve the overall reliability of sensitive equipment.
- Correct power factor to prevent voltage fluctuations.
- Mitigate harmonic distortions (2nd–25th odd order) with 100% capacity.
- Ensure stable voltage levels in facilities with renewable energy systems or large motors.
Hybrid Solutions:
- Combine SVG and capacitors for precise, cost-effective compensation of voltage dips and swells.
- Provide fast response to fluctuating loads, enhancing system stability.
Benefits of YT Electric Power Quality Products:
- Protect industrial equipment from voltage dips, swells, and transients.
- Enhance energy efficiency by reducing downtime and operational disruptions.
- Ensure compliance with power quality standards like IEEE 519.
Expert Guidance:
Intone Power is the biggest OEM manufacturer of low-voltage AHF and SVG with more than 15 years' experience. All products hold certifications for ISO9001, CE, and CQC standards, and type test reports support them.
For more information on how our Active Harmonic Filter and Static Var Generator can help improve power quality, sales@intonepower.com
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