Soft starter

Compact units with communication interface

Compact units with communication interface

Carlo Gavazzi, specialist in components for industrial and building automation, presents new soft starters. The partially controlled RSGD series and the fully controlled RSGT series enable the soft start of three-phase asynchronous motors from 5.5 kW to 75 kW at 400 VAC without complicated settings.

By means of three independently adjustable potentiometers for soft start time, soft stop time and maximum full load current (FLC), the units can be adapted by the user to the corresponding applications. A self-learning algorithm optimises the motor's start-up and run-down parameters at each start according to these user-specified parameters. Class 10 motor overload protection and other integrated monitoring functions such as phase sequence and phase unbalance fault detection and undervoltage and overvoltage monitoring eliminate the need for additional monitoring components in the electrical switchgear.

The robust design allows up to twelve motor starts per hour. A mini-USB connector on the front or, as an option, a fixed RS485 Modbus RTU interface allows easy parameter setting and real-time monitoring via software. In addition, the data logged by the unit for the last 32 starts can be retrieved. The software is available as freeware. The versions with the wide voltage range up to 400 VAC do not require an additional power supply.

Since July 2021, three-phase asynchronous motors from 0.75 kW to 1,000 kW must have IE3 efficiency or higher in accordance with EU eco-design regulations. However, the starting currents of these high-efficiency motors are many times higher than those of the previous standard motors. Soft starters prevent the possible disturbances in the mains supply caused by the high starting currents, they extend the service life of the motors and reduce the wear of the systems due to mechanical loads such as vibrations. The RSGD and RSGT series are suitable for controlling 3-phase constant speed induction motors where the starting current or the load on the motor during starting and stopping must be reduced. Typical applications are compressors, pumps, fans and conveyor belts in industrial automation and in heating, ventilation and air-conditioning technology.

With communication function

The soft starter housings have a compact design, with 45 mm or 75 mm for the RSGD series (partially controlled) and 45 mm, 75 mm or 120 mm for the RSGT series (fully controlled), depending on the type. A QR code on the front of the units links to a help menu for troubleshooting. Under the flap behind it is an RS485 Modbus RTU interface in the form of a mini-USB connector that can be used to connect the soft starter to a laptop. The configuration software SCS (Softstarter Configuration Software), which is available free of charge, enables the setting, control and monitoring of up to 247 motor softstarters. Operators can configure the softstarters individually and transfer configuration files bidirectionally, monitor instantaneous values and read errors and alarms as well as the data of the last 32 starts.