The SJ700 Series of inverters, successor to the SJ300, can develop 150 percent torque at 0 Hz. It has an improved sensorless vector control algorithm that enables it to develop more than 200 percent starting torque at 0.3 Hz. According to the manufacturer, the EzSQ (Easy Sequence) built-in programming function is like having a programmable logic controller (PLC) built into the inverter, and in many cases, the need for a separate PLC can be eliminated. The program is developed on a PC and then downloaded to the inverter using the EzSQ software provided. Mated with a general-purpose induction motor with an encoder, the inverter is given a position command, speed command, and acceleration/deceleration times. Features include patented micro-surge voltage suppression (to protect the motor winding insulation), advance trip avoidance functions, configurable sink/source logic on I/O, and built-in dynamic braking circuit in models up to 30 hp (22 kW).
Hitachi America Ltd., Industrial Systems Division, 50 Prospect Ave., Tarrytown, NY 10591; 914-332-5800; 914-332-5555 (fax); www.hitachi-america.us/inverters