A transformer designed to reduce the voltage from primary to secondary is called a step-down transformer. The transformation ratio of a transformer will be equal to the square root of its primary to secondary inductance (L) ratio.

Where are step down transformers used?

Step down transformers are used in power adaptors and rectifiers to efficiently decrease the voltage. They are also used in electronic SMPS. Other applications include: Power transmission lines.

Why do I need a step down transformer?

A step-down transformer can convert 220–240 volts down to 110–120 volts. You will need a step-down voltage transformer if you're traveling to any country with a power standard that is higher than what your appliances use.