Answer: 
Step Down Transformer: The Transformer that expands the voltage from Primary (essential) to Secondary (auxiliary) (more optional twisting turns than essential winding turns) loops called Step Down Transformer.
Step-by-step explanation:
A transformer that reduces high voltage to low voltage is called a step-down transformer. The step-down transformers are that transformers which have high turns on its primary coils than secondary. 


Where 
Vp = Voltage in Primary Coil 
Ip = Current in Primary Coil 
Vs = Voltage in Secondary Coil 
Is = Current in Secondary Coil