iCT contactors conform to IEC 61095 std and the tolerance of the rated control voltage is -15% and +10% according § 8.2.1.2.
For example, for the iCT ref.A9C20732 the rated control voltage range is 230...240Vac so the lower limit is 230*0.85=195.5Vac and the upper limit is 240*1.1=264Vac