Customers all over the world experience problems due to voltage sags.
Computers, industrial control systems, and adjustable-speed drives are
especially notorious for their sensitivity. Tripping of high-power ad
justable-speed drives is probably the main voltage sag problem. The nu
mber of trips depends strongly on the equipment sensitivity. Predictio
n methods are needed to quantify this aspect of the quality of the sup
ply. From utility and manufacturer's data, a customer can assess the c
ompatibility between a piece of equipment and the electricity supply.