Soft Starter Parameters Changing

Question: I have a soft starter that is rated for 7.5KW, and need to soft start a 3KW motor can the starters programming and / or parameters be changed in such that the starter can see the 3KW motor correctly and operate it as it should? I have found only 2 parameters where I can change the values for the motor size, but cannot set it for 3 KW, will only allow me to go down to a 5.5 KW motor size, must I plug in a PC and try through the software?

Answer: Yes, most (if not all) soft starters has this facility, you just have to figure out where to change this parameter (see the operation manual), and thus the soft starter know and derate the output power, since current sense, overcurrent protection etc. could be depended on this setting.

It could happen, that the selected parameter cannot go lower than 5.5 kW (or any lower value than the rated, for another soft starter), since the minimum power is/could also be depended on the hardware of zero current crossing and so on. Often we will have a little flexibility, but not too much, especially the low-cost could be very limited. Not wondering that, if you take a lower rated power series from the same manufacture, that you can set to 3 kW, i.e. a 4 kW soft starter, but please confirm that with the operation manual before quotation.

Anyway, you can also see, if it can be compromised with other setting parameters in order to full-fill your start up. it can be the front end fuse that is rated for the 3 kW, set the motor parameter to be 5.5 kW but the ramping time/slope is slower, initial voltage to be lower, adjust the to engage the by-pass switch/contactor(s) or combination of these.