What is the difference between a power transformer and a distribution transformer?

Power transformers are connected mainly in transmission network where they are basically used at higher voltage , while the distribution transformers are used in the distribution end hence they always face low voltage levels .

Now coming to differences

1. Since they are used in transmission network they are generally operated at > 33 KV while distribution transformers are generally connected at < 33 KV .

2. Due to the higher voltage rating the insulation level of the power transformers is very high while of distribution transformers is low .

3. Load fluctuations are less in power transformers while they are more in distribution transformers as they are directly connected to load .

4. Power transformers are designed such that they can bear Cu loss and iron loss for 24 hours hence their cooling mechanism is very strong while in distribution transformers cu loss takes place based on load cycle while iron loss are always present .

5. While designing power transformers it is taken care that it's cu loss at full loading is less. While in distribution transformers it's iron losses are kept minimum.

6. In power transformers ratings are higher hence we use superior core as CRGO steel core while in distribution transformers amorphous steel is used.

7. Since CRGO STEEL can carry more flux per unit weight hence specific weight of power transformers is less than that of distribution transformers .

8. Power transformers are designed to achieve maximum efficiency at full load. Hence according to the condition of maximum efficiency-.full load copper loss of power transformers = iron loss.

· While in distribution transformers we take that it is loaded upto 70 - 75 percent of rated output as average hence it is designed to achieve maximum efficiency at 70 - 75 percent hence according to the formula of maximum efficiency -

full load copper loss = 2* iron loss .

Formula- for maximum efficiency in transformers (x ^2 * cu loss = iron loss )where x is loading of transformer.

1. Hence for power transformers loading is 100 % hence Cu loss = iron loss .

2. For distribution transformers loading is 70 % hence 0.7 ^ 2 * Cu loss = iron loss hence Cu loss = 2 * iron loss .