Final answer:
Transformers require protective vaults to mitigate hazards due to the high voltage used for power transmission, which is then stepped down to safer levels for users.
Step-by-step explanation:
Transformers may require a protective vault because high voltages pose greater hazards. Transformers are used to transform voltages from high to low, or vice versa, which is essential for efficient power transmission over long distances with minimal line loss. However, the high voltages used in transmission lines to send power long distances are hazardous, therefore when the voltage is stepped down near the user location, protective measures such as a vault are necessary to ensure safety. This vault could be comparable to the steel or concrete domes used over reactors to contain hazardous materials in case of an accident.
Electrical Safety and Transformers
According to Electrical Safety: Systems and Devices, transformers serve many roles in electrical safety systems. They are ubiquitous in our lives, found within many household items like cell phones and power tools, changing 120 V or 240 V AC into whatever voltage the device uses. At power distribution systems, transformers step down the high voltages necessary for efficient transmission to voltages suitable for household use, typically 110 to 220 V. A magnetic ring and wire windings within the transformer allow a changing current in one winding to induce a changing magnetic field, trapping it within the ring and inducing an electromotive force (emf) in the other winding, with voltages adjusted via the ratio of loops in each winding.