It may be impossible to eliminate voltage sags totally, but with a properly designed system, and good monitoring and maintenance, it is possible to find the source of the major voltage sags and take action to reduce or contain them.
In some cases simple maintenance can reduce many of the factors that cause voltage sags, such as keeping electrical joints tight and corrosion-free and aggressive tree-trimming programs. When a man-made source such a motor startup situation occurs, a soft start controller or VFD makes a big difference.
When multiple motors start simultaneously, staggering the starts can reduce the instantaneous inrush current, thus the voltage sags. Increasing the wire size in the service drop and VA rating of the distribution transformer can also reduce voltage sags by reducing the system’s impedance feeding the load.
Power Monitors’ recorders have the capability of making valuable measurements and can be used in different modes such as in the strip chart mode and waveform capture mode shown in this whitepaper. Having the proper tools and knowledge to use these tools properly is the first step in solving most power quality issues including voltage sags.
This white paper includes: