Waveform Examples for Voltage Sag Events

Voltage Sag Event

A Voltage Sag Event will be triggered (and a waveform consequently captured) when the mains voltage RMS value drops to a lower than expected value, exceeding the triggering threshold. Common Voltages (phase to neutral) are 110V, 120V, 220V, 230V, 240V, and 277V. The typical range for the Voltage Sag trigger is -10% from nominal, as most electronic systems are designed to handle this level of sag.

Several examples of a Voltage Sag waveform signature are shown below.

NOTE: In the event of the loss of a phase to the input of the TEAL power subsystem (losing 1 phase of the 3 phase delta), you will likely see a waveform captured that will resemble this waveform. Effectively, 1 corner of the delta has collapsed, so 2 phases on the output (WYE) side drop to nearly 50% of nomimal voltage, and their frequency becomes nearly in sync, and 180 degrees out of phase with the remaining "good" phase.

Example of Voltage Sag Event, showing a fairly common sag on all 3 phases,
and each waveform is reasonably clean.

Example of Voltage Sag Event, showing severe waveform distortion, primarily on phase A

Example of Voltage Sag Event, showing severe sag and some waveform distortion

How Do I Adjust The Trigger Thresholds?

To adjust the set-points of the event triggers, please refer to the Users Manual, section 3.6.

How Do I Eliminate These Kinds of Events?

To reduce or eliminate these kinds of power events, you may need to increase the level of your power conditioning to a Voltage Regulator or a UPS. For more information, visit our Additional Power Conditioning web-pages.

For a sampling of various Case Studies that describe various power quality issues and their causes, please visit our Case Studies webpage.

For more information, please contact the TEAL Marketing Department.