A transformer designed to increase voltage from primary to secondary is called a step-up transformer.
A transformer designed to reduce voltage from primary to secondary is called a step-down transformer.
A step-up transformer is one whose secondary voltage is greater than its primary voltage. This kind of transformer "steps up" the voltage applied to it. For instance, a step up transformer is needed to use a 220v product in a country with a 110v supply.
All these transformers are designed, manufactured and supplied against specific requirement of supply voltage for the equipment. e.g. Equipments imported from American Countries work on supply voltage of 110/120 V, 1-Ph or 200/220 V, 3-Ph. Depending upon the type of equipment, Step up / step down transformers can be supplied in both auto wound type or isolated type.
Similarly step up or booster transformers are supplied for the areas, where the supply voltage is usually very low.



Switching of electrical utilities in Industrial & Commercial environment generates spikes up to 6000 Volts & high frequency power line Noises.
As the name suggests, this is basically a voltage-regulating device. However, apart from maintaining the voltage, it also provides a high degree of filtration & isolation. It also rides over brown outs & blackouts of a few milliseconds.