Single-phase voltage regulators are used with computers, office equipment, and many types of laboratory instruments. Most standard commercial voltages are single-phase. SVC series single-phase high precision automatic AC Voltage Stabilizers consists of contact voltage switch, sampling control circuit and safe motor. Three-phase voltage regulators are used mainly with industrial motors and industrial machinery. Voltage regulators provide three choices for frequency: 50-Hz, 60-Hz, and 400-Hz. 50-Hz power is used in Europe. 60-Hz power is used in the United States, Canada, Japan, and many other countries. 400-Hz power is used in aerospace applications.