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Electrician Red Seal · Question

An industrial exhaust fan with a 22 kW (30 hp) 575 V, 3-phase motor is exhibiting high inrush current, causing voltage dips and tripping the main breaker in the building. The client wants to mitigate this issue. Which of the following motor control solutions would be most effective in reducing the starting current?

A soft starter uses solid-state devices to gradually increase the voltage applied to the motor, thereby controlling the acceleration and significantly reducing

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Question: An industrial exhaust fan with a 22 kW (30 hp) 575 V, 3-phase motor is exhibiting high inrush current, causing voltage dips and tripping the main breaker in the building. The client wants to mitigate this issue. Which of the following motor control solutions would be most effective in reducing the starting current?

Answer options: ✅ A soft starter.

  • A direct-on-line (DOL) starter.
  • A manual motor starter.
  • An across-the-line starter.

Correct answer: A soft starter.

Explanation: A soft starter uses solid-state devices to gradually increase the voltage applied to the motor, thereby controlling the acceleration and significantly reducing the inrush current during startup. DOL, manual, and across-the-line starters apply full voltage immediately, resulting in high inrush currents.

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