Patent GB-530019-A (GB)
Title: Successive switching arrangement
IPC: G05D7/06
Filed: 1939-06-14
Abstract: 530,019. Switching systems. HOUDRY PROCESS CORPORATION. June 14, 1939, No. 17401. Convention date, July 12, 1938. [Class 38 (iv)] In an electrical timing mechanism controlling successive operations in industrial processes a test is applied to determine the condition of the previous operation substantially simultaneously with the initiation of another operation and the sequence of operations is interrupted immediately when the test indicates improper functioning or incompleteness of the previous operation. The invention is applicable to the control of electrically operated valves in complex chemical processes and switches each associated with the stem of a valve, as in Specification 525,050, [Group XXXVII], may co-operate with the testing circuits. The controller comprises one or more pairs of contact banks 11 over which contacts on a carrier 13 are simultaneously traversed at a selected constant speed by a motor 28 operating through change-speed gearing. Each contact segment is connected to a socket in the supporting panels and plugs 44 terminating leads from the apparatus to be tested or operated may be inserted into selected sockets so as to determine the sequence and time intervals in operation. To permit attention during operation the panel is hinged in a casing which has rear doors, and the plug leads are connected to terminals on the panel; these terminals are connected in turn to terminals on a fixed board from which wires to the apparatus proceed through a chamber 52. A control impulse is sent to each apparatus only where a moving contact is centred on a fixed contact by means of mercury switches which are tilted at such times by a cam geared to the actuating mechanism ; a further switch, similarly driven, lights an indicating lamp to facilitate manual operation of any controlled apparatus. The contact carrier may be moved by a hand wheel 34. The driving motor may be automatically reversed at the end of its travel, or a quick return obtained by a separate motor, by a plug connection, to the end contact associated with a relay. Different sequences may be controlled in each direction of movement. A modified construction is described in which a contact carrier is traversed over two concentric rings of contacts the carrier closing switches at the end of a revolution wheel for example, circuits may be changed to cause succeeding revolutions to operate a different sequence or whereby one motor may be reversed. The position of the contact carrier may be shown by a voltmeter having an indicator travelling over a circular dial and connected to a contact 128 on the carrier engaging potentiometer contacts 129 each opposite a contact segment. Two controllers may be paralleled and coupled for simultaneous driving by the same motor a clutch permitting solution and second motor being provided for individual driving. The control circuits shown in Fig. 9, include manual switches A, B whereby current may be applied to one pair of contact segments and the motor may be started in one direction by respective actuation and relays 101, 102 which lock up over retaining circuits, switches C, D whereby current may be selectively applied independent of relay 101 to each contact bank on one pair and switches E, F independent of a relay 103 whereby current may be supplied to contact banks in the other pair. The switches C ... F enable independent test on operation of each controlled apparatus. When the contact carrier reaches the last or a selected segment the relay 102 is shorted and a longer delay relay 117 energized so that the motor stops and is eventually energized reversely by relay 104 and simultaneously relay 101 is de-energized and relay 103 energized to supply control current to the second pair of contact banks whereby the sequence may be continued or a fresh sequence controlled.