Step Up transformer

Step Up transformer is a very useful device, indeed. With it, we can easily multiply or divide voltage and current in AC circuits. Indeed, the transformer has made long-distance transmission of electric power a practical reality, as AC voltage can be “stepped up” and current “stepped down” for reduced wire resistance power losses along power lines connecting generating stations with loads. At either end (both the generator and at the loads), voltage levels are reduced by transformers for safer operation and less expensive equipment. A transformer that increases voltage from primary to secondary (more secondary winding turns than primary winding turns) is called a step-up transformer. Conversely, a transformer designed to do just the opposite is called a step-down transformer.
It’s also possible to step-up voltages by increasing the number of turns on the
secondary side if we need a higher voltage.
Primary Secondary
240 volts
4 turns
480 volts
8 turns
Notice that we can determine transformer ratio by either: (1) counting the
number of turns on either side, or (2) by determining voltage on either side. We
don’t really need to know both.
OK ! We can transform the ratio of volts with a transformer, so what about
transforming amps ? The ratio of current is also changed in a transformer, but in
the opposite direction. Watch this:
Primary Secondary
240 volts
4 amps
480 volts
2 amps
In the above model transformer, the voltage is stepping-down by a ratio of
2:1 (or 480 to 240 volts) while the current increases by a ratio of 11:2 or (2 to 4
amps). So, what is actually changing in an ideal transformer is the ratio of volts
to amps.

• Transformers “step up” or “step down” voltage according to the ratios of primary to secondary wire turns.
• 
  
• 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.
• The transformation ratio of a transformer will be equal to the square root of its primary to secondary inductance (L) ratio.
• 
  For example,