An improved protection device for 3-phase electrical apparatus

  • Inventors:
  • Assignees: Alfred Davies
  • Publication Date: February 09, 1949
  • Publication Number: GB-617657-A


617,657. Protective cut-out systems. DAVIES, A. Oct. 11, 1946, No. 30374. [Class 38 (v)] An arrangement for protecting a three-phase motor against single-phasing, comprises a pair of solenoids c<1>, d<1> connected to the motor terminals a<1>, a<2>, a<3> so as to be across two of the phases, and normally closing contacts c<3>, d3 in series in the no-volt release-coil circuit of the starter switch. Failure of a phase will deenergize one or other solenoid, or insufficiently energize both, so that the spring F opens the no-volt circuit.




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