Can a transformer be applied to motor loads?

Yes, but care must be taken in the transformer's selection.  If motors are started across-the-line with a contactor, large inrush currents will occur as the motor applies large amounts torque to get to it's speed.  An isolation transformer must be properly sized to handle this additional inrush current while still maintaining a suitable output voltage.  Output voltage will drop in isolation transformers if the nameplate current rating is exceeded.  Some motors employ motor starting autotransformers, motor starting reactor or solid state reduced voltage starters to deliberately lower the motor's starting voltage and thereby lower the peak inrush current  This also extends the time a motor needs to reach full speed.  These systems are deliberately designed to produce and control this type of reduced voltage start.  A standard isolation transformer should never be used to deliberately create a lower voltage to try an mimic this effect.  

Please consult HPS's transformer/motor sizing charts or contact HPS with sizing questions.  The main data that is needed is what is the total load, what is the maximum inrush current that can occur from energizing the motors and what is the lowest voltage drop which is acceptable to this application that won't significantly delay the motor's time to ramp to full speed.  

If variable speed drives are used, drive isolation transformers or k-rated transformer which are designed to handle the additional heating of harmonics should be considered.