Solid-State Switching Devices for Switching Motors Solid-State Contactors 3RF24 solid-state contactors, three-phase Maximum permissible switching frequency depending on the starting time t a and the ON period t OP = 7,2 a e = 1 b e 10000 Switching frequency 1/h 1000 Starting time 100 = 0,05 s a = 0,1 s a = 0,2 s a = 0,4 s a = 0,8 s a = 1,6 s a = 3,2 s a NSB0_01780b 10 0,01 0,1 1 10 100 1000 in s OP For motors with a starting current of 4 to 7.2 times the rated current and with a full load (the dashed curves apply to the high currents during operation with motor starter protector) 10000 = 7,2 a e = 0,6 b e Switching frequency 1/h 1000 Starting time 100 = 0,05 s a = 0,1 s a = 0,2 s a = 0,4 s a = 0,8 s a = 1,6 s a = 3,2 s a NSB0_01781a 10 0,01 0,1 1 10 100 1000 in s OP t For motors with a starting current of 4 to 7.2 times the rated current and with 60 % load (the dashed curves apply to the high currents during operation with motor starter protector) 58 Siemens · 2009