Which of the following devices protects a motor from receiving wrong voltage levels?

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ALP CBT 2 Electrician Previous Paper: Held on 22 Jan 2019 Shift 3
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  1. Phase sequence detector
  2. Control relay
  3. Contractor
  4. Fuse

Answer (Detailed Solution Below)

Option 1 : Phase sequence detector
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Detailed Solution

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  • A phase sequence detector protects a motor from receiving wrong voltage levels.
  • The phase-sequence detector or phase-sequence checker for a three-phase supply is a device used for testing the three-phase sequence of supply in an electrical circuit or at the input of the electrical motors such as a three-phase induction motor, a  three- phase-energy meter, etc.
  • The control of the motor operation happens in such a way that the protection circuit switches off the motor during under-voltage and overload conditions and corrects the phase sequence during phase reversal conditions.
  • There are generally two types of the phase sequence detector
  •  

    1. Static type phase sequence detector

    2. Rotating type phase sequence detector

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