A low voltage potential transformer has a ratio of 20. So if you have 480 volts going in, you have 480 / 20 = 24 going out. The Starter module has a 0 - 30 volt input. The transformer ratio (20) is set in the controls parameters so the controls displays the proper voltage. If the input voltage is 460, then 460 / 20 = 23. The module sees 23 volts and knows its 460 volts. If you have a medium voltage chiller, then the ratio is 140. So 4160 volts / 140 = 29.7 volts input to the starter module.