For long it has been known that harmonics are harmful to equipment and that filters are sometimes switched off or stop working. By using the alarm function for harmonic monitoring users are alerted to changes in the electrical grid.
The limits can be set to any values. Thus the limits can be adapted to how the grid is normally functioning where the meter is set up.
This is a common phenomenon at our Swedish industry customers. In the picture above an industry customer that switches off their filters during maintenance forgot to switch them on again. Fortunately, the customer had set alarms at a 2% limit. So when they started up the industry again, they got an alarm and they could quickly switch the filters back on to make the harmonics get back to a reasonable level.