The first step toward a cost-effective solution is to
understand the sensitivity of your electronic equipment
to momentary interruptions and voltage sags.
You can find this information by consulting the equipment
manufacturer’s specifications and testing data.
You can also test the sensitivity of your equipment to
voltage sags using a measuring device called a sag generator,
which generates voltage sags and records the
responses of the equipment.
There are several possible solutions to voltage sag problems.
Generally, the least expensive approach is to
purchase controls and other electronic equipment
designed with a greater tolerance to voltage sags.
Information on these tolerances should be included in
the equipment’s specifications. Another inexpensive
and simple solution is to adjust the trip thresholds of
sensitive equipment. If you identify a relay that is
inadvertently tripping during a voltage sag, you can
change its settings—either the voltage threshold or the
trip delay. However, you can only do this if the trip settings
were set too conservatively, so it is important to
understand what they were designed to protect.
Another option is to install a coil hold-in device. These
devices are designed to mitigate the effects of voltage
sags on individual relays and contactors. Coil hold-in