Step-down transformer

Definition

A step-down transformer is a device that reduces the voltage from the primary winding to the secondary winding while increasing the current. It operates on the principle of electromagnetic induction and follows the transformer equation.

5 Must Know Facts For Your Next Test

1. The voltage ratio between primary and secondary windings is equal to the ratio of the number of turns in those windings.
2. Power (P = VI) is conserved in an ideal transformer, meaning input power equals output power minus any losses.
3. Step-down transformers are commonly used in power distribution systems to decrease high transmission voltages to safer, usable levels.
4. The efficiency of a practical step-down transformer can be high, often exceeding 90%, but it is never perfect due to core losses and copper losses.
5. The formula for a step-down transformer can be expressed as $V_s/V_p = N_s/N_p$ where $V$ is voltage and $N$ is the number of turns.

Review Questions

• What happens to current when voltage decreases in a step-down transformer?
• Explain how energy conservation applies to an ideal step-down transformer.
• How does the number of turns on each winding affect the output voltage?

Related terms

Electromagnetic Induction:

The process by which a changing magnetic field within a conductor induces a current.

Primary Winding: The coil or winding in a transformer that is connected to the input voltage source.

Secondary Winding: The coil or winding in a transformer where the reduced (or increased) output voltage is obtained.