We couldn't run our air-conditioner from the power at the marina. They rented us a box (frequency convertor not transformer) to make it work. Told us it changes the 50 to 60 cycles. We hooked it up and it worked.

They needed a 'Frequency Convertor'

Frequency Convertors from the internet: A frequency convertor is a combination of a rectifier and an inverter. The rectifier uses the generator’s alternating current (AC) output to produce direct current (DC). The inverter then converts this to produce AC output of the desired frequency. Any accompanying change in voltage is incidental to the purpose of the unit and also depends on the application for which the frequency convertor is being used.