<Dl> <Dd> P t = I V . (\ displaystyle P_ (\ rm (t)) = IV \, .) </Dd> </Dl> <Dd> P t = I V . (\ displaystyle P_ (\ rm (t)) = IV \, .) </Dd> <P> Consequently, power transmitted at a higher voltage requires less loss - producing current than for the same power at a lower voltage . Power is often transmitted at hundreds of kilovolts, and transformed to 100 V--240 V for domestic use . </P> <P> High voltages have disadvantages, such as the increased insulation required, and generally increased difficulty in their safe handling . In a power plant, energy is generated at a convenient voltage for the design of a generator, and then stepped up to a high voltage for transmission . Near the loads, the transmission voltage is stepped down to the voltages used by equipment . Consumer voltages vary somewhat depending on the country and size of load, but generally motors and lighting are built to use up to a few hundred volts between phases . The voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate . Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world . High - voltage direct - current (HVDC) electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power . Transmission with high voltage direct current was not feasible in the early days of electric power transmission, as there was then no economically viable way to step down the voltage of DC for end user applications such as lighting incandescent bulbs . </P>

What is an example of a device that uses alternating current (ac)