Semiconductor soft starter 3RW3 8.2.2 General device description The modular SIRIUS 3R system offers diverse possibilities for load feeder. Besides star-delta switching (see Ch. 5, "Fuseless load feeders 3RA") the SIRIUS soft starters 3RW3 are also available. The soft starter 3RW3 can be combined with the following SIRIUS 3R units: Contactors 3RT Circuit-breakers 3RV Thermal overload relays 3RU Electronic overload relays 3RB10 Assembly and connection are standardized. Pay attention to the assembly guidelines given in Section 8.3.2.
Functions of the load feeder In-service switching According to the definition ("Isolating" and "In-service switching", DIN VDE 0100; see Section 8.1), in-service switching of a circuit can be realized with a contactor or with a soft starter on its own. Isolating As detailed in DIN VDE 0100, isolation from the feeding line cannot be real- ized with a semiconductor element, i.e. a soft starter, a frequency converter or a contactor etc. For isolation from the feeding line, a circuit-breaker 3RV (or a different isolat- ing device that meets the requirements of the aforementioned DIN VDE 0100 ) must be used in addition to the contactor or the soft starter.
A contac- tor alone in conjunction with the soft starter is not enough! Both functions, i.e. "isolating" and "in-service switching" can be realized swiftly and easily with the soft starter 3RW3 in combination with the mod- ules from the modular SIRIUS system. Versions Two versions of the electronic soft starter are available: Standard version 3RW30 The standard version 3RW30 is available for single-speed motors. This ver- sion is available in all four sizes. The starting voltage U s , the starting time t Ron and the coasting time t Roff can be set independently of one another on the unit. It is activated by means of a cycling contact IN.
Special variant 3RW31 The special version 3RW31 serves to cycle pole-changing motors (Dahlander winding). The following can be set independently: Starting voltageU s Starting time, first speed t R1 Starting time, second speed t R2 . The unit does not have a coasting function. The set starting voltage applies to both ramp times t R1 and t R2 . The respective ramp time is chosen via two inputs IN1 and IN2, which also activate the soft starter. The units in the 3RW31 series are only available in the S0 size. 8-10 Stand 08/99