Power electrical device vs Distribution electrical device:
Power transformers are used for transmission & receiving purpose, whereas distribution transformers are used just for distribution purpose.
Power electrical device voltage magnitude relation varies b/w 756 potential unit to 11kV. Whereas the distribution electrical device voltage magnitude relation varies b/w 33kV to 430V.
Power transformers sometimes have higher MVA rating compare to distribution transformers.
To understand the higher than, I need you to know the various voltage levels that we tend to use from beginning power generation till its distribution;
1-Generally, electric power is generated at low voltages i.e. 11kV. giant generators are designed to get voltage starting from eleven potential units to twenty-eight potential unit and frequency in fifty Hz or sixty Hz vary. however, to get at 33kV, the dimensions of the generator can be double as a giant because of the size of the 11kV generator.
2-Now this generated energy is transmitted over the transmission lines of many hundred kilometres once a current flows through these wires some energy is lost as heat. the upper this, the additional heat is lost. therefore we want to transmit the ability at low current to attenuate the conductor size and losses. to cut back this we want to extend the voltage. In transmission/generating stations we tend to use the transformer to extend the voltage to mention 220 potential unit or higher than, these transformers are known as-as power transformers.
3-Now this EHV cable terminates at the native receiving station, wherever 220 potential unit voltage is stepped all the way down to say thirty-three or 11kV exploitation the decrease transformers, these transformers are known as-as Power transformers.
4-Now, these 11kV voltage line is then distributed on each distribution station of the town, wherever the voltage is any step all the way down to 430V AC exploitation the transformer. Transformers used here are known as Distribution transformers.
5-This 430V (3 sections & one Neutral) AC is then given to industrial and unit shoppers. usually, unit shopper gets 230V as a customary single section voltage, this configuration is achieved with one section and one neutral wire.