In the example, the motor described is connected as a 3-phase machine at what primary voltage level?

In the example, the motor described is connected as a 3-phase machine at what primary voltage level?

• A. 13.2 kV
• B. 480 V
• C. 208 V
• D. 277 V

Answer: (A)

Large three-phase motors in industrial settings are often fed from high-voltage distribution on the primary side to reduce currents and copper losses, with a transformer stepping down to the motor’s actual operating voltage on the secondary. Seeing a primary voltage level of 13.2 kV indicates the system is designed for high-voltage service on the supply side, typical for large motors connected through substations or feeders that later drop to their lower winding voltage. The other voltages listed are common for smaller or differently configured motor or lighting circuits (for example, 480 V or 208 V as direct motor voltages, or 277 V in certain lighting-fed systems), but they represent lower-voltage, on-site distribution rather than the high-voltage primary feed described. So, 13.2 kV is the correct primary voltage level for this 3-phase motor setup.

Large three-phase motors in industrial settings are often fed from high-voltage distribution on the primary side to reduce currents and copper losses, with a transformer stepping down to the motor’s actual operating voltage on the secondary. Seeing a primary voltage level of 13.2 kV indicates the system is designed for high-voltage service on the supply side, typical for large motors connected through substations or feeders that later drop to their lower winding voltage.

The other voltages listed are common for smaller or differently configured motor or lighting circuits (for example, 480 V or 208 V as direct motor voltages, or 277 V in certain lighting-fed systems), but they represent lower-voltage, on-site distribution rather than the high-voltage primary feed described. So, 13.2 kV is the correct primary voltage level for this 3-phase motor setup.