With three-phase compressors, a voltage imbalance of greater than ________ will cause the windings within a motor to generate heat beyond safe levels, leading to premature motor failure.

With three-phase compressors, a voltage imbalance of greater than ________ will cause the windings within a motor to generate heat beyond safe levels, leading to premature motor failure.

• A. 2 percent
• B. 5 percent
• C. 10 percent
• D. 20 percent

Answer: (A)

Balanced voltages are essential for a healthy three-phase motor because they create a symmetrical rotating magnetic field. When a voltage imbalance occurs, the phase voltages become unequal, distorting the rotating field. This drives unequal currents through the windings and increases copper losses (I²R losses) and other stray losses, which shows up as extra heat in the windings. Once the imbalance passes about two percent, the heat can exceed what the insulation and windings can safely handle, leading to insulation damage, reduced efficiency, and potential premature motor failure. So keeping the imbalance around two percent or less minimizes dangerous heating. Larger imbalances would cause even more heat and greater risk.

Balanced voltages are essential for a healthy three-phase motor because they create a symmetrical rotating magnetic field. When a voltage imbalance occurs, the phase voltages become unequal, distorting the rotating field. This drives unequal currents through the windings and increases copper losses (I²R losses) and other stray losses, which shows up as extra heat in the windings. Once the imbalance passes about two percent, the heat can exceed what the insulation and windings can safely handle, leading to insulation damage, reduced efficiency, and potential premature motor failure. So keeping the imbalance around two percent or less minimizes dangerous heating. Larger imbalances would cause even more heat and greater risk.