ATT Field Competency (FC) Practice Test

A step-up transformer is designed to increase the voltage from its primary coil to its secondary coil. This function occurs because of the winding ratio between the primary and secondary coils. In a step-up transformer, the secondary coil has more turns than the primary coil. As a result, when an alternating current passes through the primary coil, it creates a magnetic field that induces a greater voltage in the secondary coil due to the increased number of turns.

The relationship between the number of turns in the coils and the voltages is described by the transformer equation:

\[

\frac{V_s}{V_p} = \frac{N_s}{N_p}

\]

where \(V_s\) is the secondary voltage, \(V_p\) is the primary voltage, \(N_s\) is the number of turns in the secondary coil, and \(N_p\) is the number of turns in the primary coil. For a step-up transformer, since \(N_s > N_p\), it results in \(V_s > V_p\), indicating an increase in output voltage.

This concept is crucial in applications where higher voltage is required for efficient power transmission over long distances, minimizing energy losses.