What is the purpose of a 380/220V control transformer when you could just use one phase and a neutral for your motor control circuit?
In the industrial network the neutral is not always present. Most machines have three phase and PE connection. PE is used only for safety purposes, so no device may use it as power supply connection. 

Another fact when using neutral and phase is that if neutral gets missing, your control voltage will become high, blowing up the PLC and other control circuit.