GB1326315A - Supply termination alarm - Google Patents

Abstract

1326315 Supply termination alarm PLESSEY CO Ltd 25 April 1972 [25 June 1971] 29875/71 Headings B3B and B3T A supply termination alarm assembly includes a guideway g by which a supply in the form of a length of solid material R is advanced from an access point A to a delivery point D, a first detector (not shown) situated at the access point, a second detector (not shown) situated at an intermediate point I of the guideway separated from the first detector by a first distance d1 and from the delivery point by a second distance d2, each detector operating on the advance of the rear end of said length past the point at which the detector is situated, the sequential operation of the first and second detectors affording a measurement of the advance of the said end over said first distance, and simulation means operable in dependence on said measurement to simulate the advance of the said one end over the second distance, and to operate an alarm indicating termination of supply on simulation of the advance of the said end to the delivery point. The simulation means may be a counter operable to measure the advance of said end over the first distance in steps, the counter being reversible on operation of the second detector, the alarm operating when the count on the counter is reduced to zero. Two counters may be used, one operative during movement of said end over said first distance, the second operative over said second distance, the alarm operating when the counters record the same count. Alternatively a timing device may be used. A warning signal generator may be operable on operation of a detector.