Building electrical services: Large buildings supplied at medium voltage require a substation/mini-sub. What is the main item of equipment contained in such a substation? Choose the correct device.
Interview
Technology
Difficulty: Easy
Choose an option
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AStep-down distribution transformer (MV to LV)
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BBattery inverter (UPS only)
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CCapacitor bank only
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DDiesel generator only
Answer
Correct Answer: Step-down distribution transformer (MV to LV)
Explanation
ConceptThe heart of a building substation is the MV→LV transformer, stepping medium voltage (e.g., 11 kV) down to low voltage (e.g., 400/230 V). Switchgear, protection, and meters accompany it, but the transformer is the central item.
Final AnswerStep-down distribution transformer (MV to LV)