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Electrician Red Seal · Question

A Squirrel Cage Induction Motor (SCIM) is controlled by a Variable Frequency Drive (VFD). The VFD is showing an 'overcurrent' fault during motor acceleration. What is a common cause for this type of fault?

An overcurrent fault during acceleration often occurs when the VFD attempts to accelerate a high inertia load too quickly. The motor requires a large initial cu

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Question: A Squirrel Cage Induction Motor (SCIM) is controlled by a Variable Frequency Drive (VFD). The VFD is showing an 'overcurrent' fault during motor acceleration. What is a common cause for this type of fault?

Answer options:

  • Input voltage to the VFD is too low. ✅ The VFD's acceleration time setting is too short for the load inertia.
  • The motor is running in reverse.
  • The VFD's carrier frequency is set too high.

Correct answer: The VFD's acceleration time setting is too short for the load inertia.

Explanation: An overcurrent fault during acceleration often occurs when the VFD attempts to accelerate a high inertia load too quickly. The motor requires a large initial current to overcome the inertia within the short ramp-up time, leading to an overcurrent condition. Increasing the acceleration time allows the motor to gain speed more gradually, reducing the peak current demand.

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