GB168884A - An improved electric maximum automatic cut-out - Google Patents

Abstract

168,884. Koolhaas, D. J. B. Aug. 30, 1920, [Convention date]. Electromagnetic and magnetic switches contacts.-An electro magnetic overloac switch or cut-out com prises a magnetic circuit including two cores a, b joined by a bar c. One limb a carries a low-resistance series coil e, the other b carrying a high-re sistance shunt winding f. At the other end o the cores is mounted a block of insulating material recessed tc hold two mercury con tacts j, k, which are adapted to be con nected together by a floating armature d with limbs d<1>, d<2> dipping into the mercury when the armature is in its unattracted position. Contact blocks h, g, i carry connections by which the coil e is connected in series with the line, the main current passing through the armature d and mercury contacts j, k, and the shunt coil f being connected directly across the incoming and outgoing leads of the cut-out. With normal circuit conditions the armature d remains unattracted, but if the line current exceeds a predetermined maximum the coil c will be sufficiently energized to attract the armature d, thereby breaking its circuit. With the armature in its attracted position a closed magnetic circuit is established, and if the overload condition persist, the shunt coil will be sufficiently energized to maintain the armature d in its displaced position. Release of the armature d may only be effected either by momentarily breaking the external circuit or increasing the resistance of the external circuit sufficiently to decrease the energization of the coil f below the minimum at which it will maintain the armature d in its attracted position.