Commissioning13.2 Commissioning the 3RW40SIRIUS 3RW30 / 3RW40112 Manual, 10/2018, NEB535199502000/RS-AB/00513.2.4 Setting the starting voltageU potentiometerThe starting voltage value is set with the U potentiometer. This value determines the startingtorque of the motor. A lower starting voltage results in a lower starting torque (softer start)and a lower starting current.The starting voltage selected must be sufficiently high to ensure that motor starts upsmoothly as soon as the start command is received by the soft starter.13.2.5 Setting the ramp timet potentiometerYou define the length of the required ramp time with the t potentiometer. The ramp timedetermines the time taken to increase the motor voltage from the parameterized startingvoltage to the mains voltage. This time merely influences the motor's acceleration torque,which drives the load during the ramp-up process. The actual motor starting times are load-dependent and can differ from the 3RW soft starter settings.A longer ramp time results in a lower starting current and a reduced acceleration torque asthe motor starts up. The startup is slower and smoother as a result. The ramp time must belong enough for the motor to reach its nominal speed. If the time selected is too short, inother words if the ramp time ends before the motor has started up successfully, a very highstarting current that can even equal the direct starting current at the same speed occurs atthis instant.The SIRIUS 3RW40 soft starter additionally limits the current to the value set with the currentlimiting potentiometer. As soon as the current limiting value is reached, the voltage ramp orthe ramp time is interrupted and the motor is started with the current limiting value until it hasstarted up successfully. In this case, the motor ramp-up times may be longer than themaximum parameterizable 20 seconds ramp time or the ramp time that is actually set on thesoft starter (for further information about the maximum ramp-up times and switchingfrequencies, refer to the Technical data chapter > 3RW30 13, 14, 16, 17, 18-.BB.. powerelectronics (Page 130)) ff. and 3RW40 24, 26, 27, 28 power electronics (Page 146) ff.).
