What is one of the most common problems on a three phase electrical system?

Voltage unbalance is one of the most common problems on three phase systems, and can result in severe equipment damage, yet it is often overlooked. For example, a voltage unbalance of 2.3 percent on a 230 V motor results in a current unbalance of almost 18 percent, causing a temperature rise of 30 °C. While a digital multimeter (DMM) and some quick calculations can be used for averaging voltage readings, a power quality analyzer provides the most accurate information about unbalance.