🔍 Key Concepts

• Difference between a lighting ballast and a power transformer • Visual features of a three-phase dry-type transformer (three separate coils/cores) • How a current transformer (CT) looks compared to a power transformer

💭 Think About

• Which illustration clearly shows three distinct coils or phases that could correspond to a three-phase system? • Which device is most suitable for stepping down line voltage for lighting circuits, rather than just sensing current or controlling fluorescent lamps? • Look at the number and arrangement of terminals: which option appears designed to handle three input lines and three corresponding outputs?

✅ Before You Answer

• Identify which option shows three identical coil sections side by side, typical of a three-phase transformer • Eliminate the device that looks like a fluorescent lamp ballast (long, narrow metal case) • Eliminate the device that has a large circular opening through the middle, characteristic of a current transformer used for measurement, not power transformation