Digital Type Phase Converter. Efficiency is excellent versus others phase converters. However, when more than 50% load is applied to the motor, the 'U' and 'W' current values are balanced. If used on a motor with a horsepower lower than 7.5HP(for example 5HP, 3HP, 2HP motor), the motor may generate heat, make noise, and cause problems with motor operation.
eBay