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Apparatus for controlling the starting of a three phase load with its normal phase sequence

  • US 4,667,264 A
  • Filed: 03/12/1986
  • Issued: 05/19/1987
  • Est. Priority Date: 08/16/1983
  • Status: Expired due to Term
First Claim
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1. An apparatus for controlling the starting of a three phase load with its normal phase sequence comprising:

  • input terminals for receiving a three phase electric energy through external supply lines;

    internal supply lines coupled to said terminals for carrying said three phase electric energy to said load;

    phase sequence sensing means coupled to said internal supply lines for sensing a phase sequence of the received three phase energy;

    phase change-over means connected in said terminal supply lines for reversing the phase sequence of the electric energy supplied to said load when said phase sequence sensing means senses a reverse phase sequence of the received three phase energy;

    open phase sensing means having a first circuit connected across the first and second lines of said supply lines for sensing the presence or absence of an open phase in the first and second lines of said internal supply lines and a second circuit connectes across the second and third lines of said internal supply lines and including a time delay means operated by said first circuit, after a predetermined time from the operation of said first circuit thereby enabling said second circuit to detect ther presence of absence of an open phase in any one of said internal supply lines; and

    switch means coupled to said open phase sensing means for permitting the starting of said load by said supply lines through said phase change-over means after a predetermined time from the operation of said first circuit when said open phase sensing means detects the absence of an open phase and for inhibiting the starting of said load when said phase sensing means detects the presence of an open phase.

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