GB439573A - Improvements in switchgear specially applicable to motor starters - Google Patents

Abstract

439,573. Automatic circuit-breakers; controllers. COX, F. B., 65, Fleet Street, Liverpool. June 6, 1934, No. 16780. [Classes 38 (iii) and 38 (v)] A releasing member, movable under gravity or by a spring to release a contact-retaining device, is held against release by automatic means controlled by potential or current variation and is set by movement of the switchoperating handle in closing the switch. The member has connected to it a cam, toggle, or equivalent, engaging the retaining means during the release movement so that, when the switch has been closed and the member set, if the operator returns the handle slowly and retards the release movement of the member, release of the retaining device is ensured by the cam or toggle without the use of percussive action such as is described in Specifications 264,552, [Class 38 (iii)] and 348,590. As applied to the switch shown in Specification 412,246, the movable contact O co-operating with the contact P' is mounted on a shaft J carrying a detent 2 and an arm j <1> provided with a pin j<2> which engages in a slot e<4> of a link e<2>. The spring-controlled closing handle b<1> is fast on a shaft B carrying a portion D which, when b <1> is moved from the position of Fig. 2 to that of Fig. 1, engages a part e<6> on an armature E loose on the shaft B, whereby E is moved into engagement with a no-volt magnet F and closes the breaker. The parts are retained, subject to F being energized, by engagement of 2 with a detent 3, 5 pivoted at 4. The magnet F can be de-energized on voltage-failure or by the opening of its winding G by contacts of an overload relay R, whereupon a spring e<1> returns E to the position of Fig. 2, in which movement a cam 6 on E engages the detentarm 5 and moves 3 clear of 2 so that the spring 1 opens the breaker. If the armature E fails to be retained by the magnet, and the handle is returned slowly to the " off position, the return of E is similarly retarded by the interengagement between D, e‹, but the engagement of 6 with 5 ensures the release of the detent 2. In Fig. 3 (not shown), the armature E carries a disc on which is mounted a crank-pin which is linked to a detent lever retaining the detent 2. Rotation of the disc causes the pin to move to or over the dead-centre and impart a small releasing movement to the detent lever In Fig. 4 (not shown), a cam similar to that of Fig. 1 may push a retaining toggle for the movable contact over the dead-centre, a throwoff spring for the contact completing the action. In both the above modifications, the operating handle is shown mounted on the armature, and the contact is connected to the latter by an arrangement similar to e<2> in Fig. 1. The armature may alternatively be retained by a latch acted on by an overload coil or bimetal element, Fig. 5 (not shown).