Explain the working of single phasing preventer with neat diagram.

Explain the working of single phasing preventer with neat diagram.
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1 Answer

Answer :

Working of single phasing preventer: 

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Single phasing preventers are generally used for small / medium capacity motors. Single phasing preventers are connected in secondary of line CTs. These mainly contain a negative sequence filter. The output of negative sequence filter is fed to the level detector, which further sends tripping command to starter or CB. When one of the three input lines get disconnected because of any reason, ultimately the NC contact gets opened which stops the motor to avoid further damage when single phasing occurs. 

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