# The Naked Scientists Forum

### Author Topic: Transformer ratio and output question  (Read 1139 times)

#### Europan Ocean

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##### Transformer ratio and output question
« on: 15/03/2015 03:45:17 »
Good day, I am interested in transformers, looking at being a technician. So if regarding numbers of coils on the input and output sides of a transformer, the ration is 1:2 primary/secondary, and say 200 volts go into the primary, is the output from the secondary coil 100V or 400V? From reading it should be less than 200V but it isn't clear of exact output. Hand written notes and notes in print contadict, and I am using the web.
« Last Edit: 15/03/2015 06:06:41 by Europan Ocean »

#### Colin2B

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##### Re: Transformer ratio and output question
« Reply #1 on: 15/03/2015 08:44:45 »
Good day, I am interested in transformers, looking at being a technician. So if regarding numbers of coils on the input and output sides of a transformer, the ration is 1:2 primary/secondary, and say 200 volts go into the primary, is the output from the secondary coil 100V or 400V? From reading it should be less than 200V but it isn't clear of exact output. Hand written notes and notes in print contadict, and I am using the web.

It is better to talk about turns rather than coils to avoid confusion. A transformer can have more than one set of coils on the secondary side each with it's own output.

In the example you give we would put twice as many turns on the secondary coil as on the primary. This will result in the secondary (output) voltage being twice the primary (input) voltage. In your example 200V in 400V out, so the voltages are in the same ratio, 1:2, as the turns.
Ignoring losses, power (VA, Volt Amps) at the input and output will be the same so the current available at the output will be half what is put in.

Hope that helps, all the best in your studies
« Last Edit: 15/03/2015 10:03:50 by Colin2B »

#### The Naked Scientists Forum

##### Re: Transformer ratio and output question
« Reply #1 on: 15/03/2015 08:44:45 »