GB1061890A - Interlock system for a contactor or contactors associated with an isolating switch - Google Patents

Abstract

1,061,890. Electromagnetic contactors; interlocking of switches. CONTACTOR SWITCHGEAR Ltd. Nov. 1, 1965 [Aug. 1, 1964], No. 30416/64. Heading H2B. An electromagnetic contactor is connected in series with an isolating switch which is provided with a latch which normally prevents opening of the isolator and which can be released only if the contactor contacts are open. An operating shaft 12, carrying a handle 11 of the isolator, also carries a boss 14 normally latched by a plate 16 biased by a torsion spring 18. A pushbutton 20 is arranged to tilt a lever 22 which engages a stud 33 to release latch 16. Attached to lever 22 is one end of a cable 24 slidable in a sheath 25, the other end of the cable being attached to a plate 27 pivoted on the contactor and engageable by a latch plate 35, carried by the movable contact bridge 34 of the contactor, when the contacts are closed so as to prevent lever 22 being tilted. In a modified arrangement (Fig. 4, not shown) the cable 24 is placed under tension by two strong springs (44), (46) whose forces normally cancel but in the event of cable breakage serve to apply a greatly increased resistance to push-button 20 to indicate the fault. The invention may be employed with a contactor having a pivoted armature (Fig. 5, not shown). In another arrangement (Figs. 6, 7, not shown) push-button 20 is coupled to the latch by a toggle linkage (62), (63) which is held straightened by the cable 24 so long as the contactor is open but is collapsed so that the pushbutton cannot operate the latch when the contactor is closed. In a further arrangement (Fig. 9, not shown) the cable 24 is directly coupled to the contact bridge 34 and normally provides a pivot (75) about which the latch plate turns when push-button 20 is depressed but which is retracted when the contactor closes so that the latch plate turns about a second pivot (72) which is so close to shaft 12 that release is impossible. In yet another arrangement (Fig. 10, not shown) button 20 acts on the latch plate by a pin (21d) which passes through a hole (79) in a plate (78) attached to the cable 24, the plate (78) being moved by closing of the contactor to prevent pin (21d) passing through the hole (79). When several contactors are associated with a single isolator switch, the plates 27 of the contactors are coupled together by further cables 24 in the arrangements of Figs. 1-4 but in the other arrangements where the cable is held taught when the contactor is open a compensator device (Fig. 8, not shown) is necessary to ensure that latch 16 can only be released when all the contactors are open.