Power transformer:- 

Power transformer is connect between generating station and transmission line to step up the voltage before transmission in order to minimize ohmic losses during transmission.

The power handed by power transformer or kva rating of power transformer is much higher than as distribution transformer .

Due to higher voltage rating insulation need to be increased in power transformer.

By increasing insulation the separation between low voltage and high voltage winding increased.so leakage also increase or power transformer has higher leakage reactance.

Due to high leakage impedance of power transformer it's short circuit current reduces and it is better protected against fault.

Distribution transformer:-

Distribution transformer is connected at the load end in order to stepdown the voltage before delivering power to the load.

Distribution transformer is operate at lower voltage as compare to power transformer.

Comparison between power and distribution transfomer:-

1 power transformer:-

  1. Used at higher voltage EX:- 400kv ,220kv,66kv.
  2. Rating above 200 MVA.
  3. Large in size.
  4. Operate at full load.
  5. Efficiency is used.
  6. Design to have maximum efficiency at full load.
  7. Copper and iron losses occurs entire day.
  8. Due to high voltage rating of power transformer it is operated at high flux density.
  9. Design for proper utilization of core.
  10. Design to minimize copper losses.
  11. Voltage regulation is not critical.
2 Distribution transformer:-

  1. Used at low voltage EX :- 11kv,6.6kv,3.3kv,440v or 220v.
  2. Rating less than 200 MVA .
  3. Smaller in size.
  4. Operate at variable load.
  5. All day efficiency is used.
  6. Design to have maximum efficiency at 50% to 75% of full load.
  7. Core loss occurs entire day and copper loss depends on load.
  8. Lower flux density.
  9. Does not properly used the core.
  10. Size and weight can not be reduced.
  11. Design to minimize core loss.
  12. Voltage regulation is critical.