Patent GB-657939-A (GB)
Title: Improvements in electro-magnetic switches with double break
IPC: H01H50/22
Filed: 1949-05-30
Abstract: 657,939. Electromagnetic switches. PAOLO, P. S. FU. May 30, 1949, No. 14395. Convention date, May 31, 1948. [Class 38(v)]. In a readily-assembled electromagnetic switch in which a single rectilinearly moving core 25 operates ,a number of movable contacts 16, a corresponding number of contact-carrying elements are mounted on three rods placed at the points of a triangle and passing through holes 3 in the elements, the whole thereby forming a supporting frame to which the magnet is attached. Each element comprises two identical insulating plates 1 which have flat backs and are placed face to face so as to provide internal recesses to carry the contact elements. The Figure shows three and a half of such elements assembled and the cavities 4 thereby formed are used for the reception of ears projecting from the end plates of the laminated magnet 23, the ears being pierced to receive the lower two of the three supporting rods. The movable contacts 16 are mounted on a single channelshaped rod 21, and in assembling, insulating blocks 20 are first placed round the rod 21, and then held in place by frames 17 each of which carries a spring 19 pressing upwards a plate 18. The rod 21 with its members 17...20 is then placed in position below the assembly of elements 1 and two rectangular contact rods 16 for each contact unit are then inserted between the plate 18 and the top of the frame. Since these rods rest on projections on the members 1, the rod 21 with its attachments is held in place. After the magnet has been attached and the supporting rods inserted in the holes 3, elastic plates are placed at the ends of the supporting frame and the whole tightened by nuts on the rods. Refractory plates 15 forming arc shoots are then inserted, and after them the fixed contact elements which are introduced from the top, snap into position past projections 48 and hold the plates 15 in place by entering hollows 47, Fig. 5. Each fixed contact element consists of a roller 6 mounted between two plates and a spring 11 arranged between a T-shaped plate 10 and a washer which are pressed outwardly by it against the plates. A fork terminal is inserted between the washer and a plate 7. The magnetic coil is then put in position and after it the movable core 25 which has two non-magnetic end plates 26 extending upwards and provided with notches 27A so that the upper end of the plates corresponds in shape to the inside of the channelshaped bar 21 and is made to occupy this channel by first moving the bar 21 sideways till notches 27 come opposite the plates. The elastic plates referred to above allow this movement. The bar 21 is thus fixed to the movable core 25 and moves up with it when the magnet is energized to cause the contacts 16 to engage the contact rollers 6. Other fixed contact elements may be arranged to be engaged by the rods 16 in their lower position and the core 25 may also carry below it a movable contact adapted to bridge two additional fixed contacts. A number of electromagnets may also be used. Specification 661,324, [Group XXXV], is referred to.