Transformer Voltage Drop

[djr3203]

All,

I am a junior engineer and I just received an email with a statement that I believe to be incorrect. Can you let me know what your thoughts are? Here is the statement:

'Transformer transfers energy thru magnetic induction coils and its associated turn ratio. There is no direct contact from primary to secondary, therefore, voltage drop only accounts up to the secondary side of the transformer.'

I thought a voltage drop at the primary due to voltage drop along the primary feeders would result in a voltage drop at the secondary proportional to the ratio between the primary turns to the secondary turns. If there was a 2% voltage drop at the primary, wouldn't this result in a 2% voltage drop at the secondary? Am I missing something?

DJR

 

[magoo2]

Your quoted statement reads correctly if you are just considering the drop through the transformer.

If you have a line ahead of the transformer that results in a 2% drop, then on the secondary of the tranmsformer you would have 2% drop plus whatever the drop is through the transformer.

 

[djr3203]

The statement was in response to the voltage drop along the primary feeder and not in reference to the voltage drop through the transformer. I was trying to explain to him the statement in your second sentence, which he kept telling me I was incorrect. Thanks for the backup.

DJR

 

[Silja]

Almost all transformers have the ability to change voltage ratio through the tap changer online or offline. So if it is 2% drop on the prime side, you can change tap to make up this 2%(normally 2.5% per step on the tap) and keep secondary voltage unchanged.