A DEVICE FOR SWITCHING OFF A THREE PHASE ELECTRIC MOTOR INSTANTANEOUSLY WHEN ONE OR TWO PHASES FAIL

摘要

A device for switching off a three phase electric motor instantaneously when one or two phase fail comprising three electromagnetic coils each connectable in series with each of the phase of a three phase electric motor, means for mounting the electromagnetic coils, three magnetic cores each being fixedly mounted at one end of each of the electromagnetic coils, a swinging arm assembly, means for mounting it in front of the said magnetic cores, three magnetic weights, movably suspended between the magnetic cores and a the swinging arms assembly, a relay circuit consisting of a movable contact point and a fixed contact point, said movable contact and fixed contact points being adapted to close or open the connection to the ''No Volt'' coil of the three phase electric motor starter and means for limiting the movement of the movable contact point.