Step-Up & Step-Down Transformers

Step-up Transformer:

When the number of turns in the primary coil is less than the number of turns in the secondary coil, it is called a step-up transformer. The secondary voltage is greater than the primary voltage.

N_s > N_p
E_s > E_p
I_s < I_p

From the equation, \( \frac{E_s}{E_p} = \frac{N_s}{N_p} \)

We find that to increase the secondary voltage E_s, \( \frac{N_s}{N_p} \) must be greater than 1. This means that N_s must be greater than N_p

Also from \(\frac{N_s}{N_p} = \frac{I_p}{I_s} \) when N_s > N_p, then I_s < I_p

Step-down Transformer:

The number of turns in the secondary coil is less than the number of turns in the transformer. 

N_p > N_s
E_p > E_s
I_p < I_s

The secondary voltage is less than the primary voltage (V_p)