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Electrician Red Seal · Question

An electrician is testing a PLC-controlled system. A proximity sensor is used to detect the presence of a metallic object. The sensor is a 3-wire NPN type. When the metallic object is detected, what should the output of the sensor typically be?

An NPN (Negative-Positive-Negative) transistor output sensor is a 'sinking' type. When activated, it connects its output to ground (0 V), drawing current from t

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Question: An electrician is testing a PLC-controlled system. A proximity sensor is used to detect the presence of a metallic object. The sensor is a 3-wire NPN type. When the metallic object is detected, what should the output of the sensor typically be?

Answer options:

  • It provides a positive voltage output (+V). ✅ It provides a ground (0 V) output, sinking current.
  • It goes into an open-circuit state.
  • It changes its operating frequency.

Correct answer: It provides a ground (0 V) output, sinking current.

Explanation: An NPN (Negative-Positive-Negative) transistor output sensor is a 'sinking' type. When activated, it connects its output to ground (0 V), drawing current from the PLC input module.

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