1. Transformer Efficiency

2. The relationship that we derived for the transformer is:

3. If the transformer is 100% efficient all, ALL of the electrical power generated across the primary winding must be delivered to the secondary winding:
As P= IV
For a totally efficient transformer Pp = Ps
i.e. IpVp = IsVs

4. The ratio: Therefore measures the efficiency of the transformer.
In practise large power transformers have an
Efficiency of around 98%

5. Question
The primary coil of a step down transformer has 5000 turns and the secondary coil has The primary has 1150V across it.
Calculate the e.m.f. generated in the secondary coil.
The transformer is 90% efficient. Calculate the average current generated in the secondary coil.