The term is “step up voltage.” There us no definition in the dictionary about this term as a whole. But there is a definition of “step up” and “voltage” separately. Step up is a verb meaning to increase especially in stages. Voltage is an Electromotive force or potential difference usually expressed in volts. “Step up voltage” is used in the electrical field.
The step up voltage of an appliance is the voltage when it was switched on. An example is that air-conditioning units should not be turned off and on if the vacant time is less than two hours because there’s a step up voltage before the voltage is stabilized. It means that the step up voltage is different from the voltage of an appliance. All appliances have step up voltage and it consumes more current thus resulting to higher power consumption. It is advisable that appliances should not be frequently switched off and in to avoid step up voltage. This can also help us conserve energy.