Station ______ transformers are the distribution transformers for substations, providing single-phase power for lighting and three-phase power for equipment.

Station ______ transformers are the distribution transformers for substations, providing single-phase power for lighting and three-phase power for equipment.

• A. Service
• B. Instrument
• C. Potential
• D. Current

Answer: (A)

The station needs its own auxiliary power to run lighting, control rooms, fans, and other equipment inside the substation. A station service transformer is dedicated to supplying this internal power, typically giving a single-phase output for lighting and a three-phase output for equipment. This keeps the substation’s internal loads separate from the main power transformers that feed external circuits. Instrument transformers, such as potential transformers and current transformers, exist for measurement and protection purposes—they scale down voltages or currents for meters and protective relays, not to power station loads. That’s why they aren’t described as supplying the station’s lighting and equipment. So, the best fit for this description is the station service transformer.

The station needs its own auxiliary power to run lighting, control rooms, fans, and other equipment inside the substation. A station service transformer is dedicated to supplying this internal power, typically giving a single-phase output for lighting and a three-phase output for equipment. This keeps the substation’s internal loads separate from the main power transformers that feed external circuits.

Instrument transformers, such as potential transformers and current transformers, exist for measurement and protection purposes—they scale down voltages or currents for meters and protective relays, not to power station loads. That’s why they aren’t described as supplying the station’s lighting and equipment.

So, the best fit for this description is the station service transformer.