... frequency inverter, ac inverter, frequency converter, variable frequency drive - Constant torque type....2. Features OF VARIABLE SPEED DRIVE:sy8000 VARIABLE ... : within -15%10%; voltage imbalance: <3%; frequency fluctuation: within 5%.outputVoltageSingle phase,220V & 3 phase ... 485 connector RS485+,RS485-4 bits LED displaysetting frequency, output frequency, output voltage, output current, motor speed, ...