Patent GB-276770-A (GB)
Title: Improvements in automatic electrical power station control apparatus
Filed: 1926-06-22
Abstract: 276,770. Ross, T. W., Ryder, C., and Metropolitan-Vickers Electrical Go., Ltd. June 22, 1926. Running generators in parallel. -. Load responsive relays cause the operation of a controlling device to initiate the operation of automatic. starting equipments associated with each of a number of machines to cause them to be started up and closed down in sequence according to the load demand. A voltage relay is connected with its contacts in parallel with those of an overload relay. Overload and underload relays are operated differentially in accordance with the load current and a current depending upon the number of machines in operation. Means are provided to change the sequence of operation at will. Time delay relays control the starting up and closing down operations and provision is made for starting up the next machine in sequence if a lock-out relay on any machine, should be operative, or if a machine should fail to start. A drum controller 51 is driven by a reversible motor 52 the forward and reverse fields of which are controlled by contactors 59, 61 respectively. The system shown is for three machines and interchangeable plugs 46, 48, 50 proper to the first, second and third in sequence may be placed in either of sockets 45, 47, 49 as desired. The starting of machines is effected by voltage relay 20 or overload relay 22 which energize time-delay relay 56 over contact 15 of the controller; the closing down by underload relay 23 which energizes time delay reverse relay 70 over contact 16 of the controller. The relays 22, 23 are energized by coils 25, 28 responsive to the load current opposed by coils 26, 30 carrying the currents-flowing from the control bus-bars 34, 134 through a resistance 35 and parallel connected resistances 36 - - 38 which last are in circuit only when the machine to which each relates is running. Overload relay 22 closes when the load coil 25 wins and underload relay 23 when the machine coil 30 wins. When time delay relay 56 closes contacts 57 the contactor 59 is energized through interlock 63 and controller contact 13 from the control busbars. The controller then runs forward and at contact 5 - - 7 closes a circuit for the starting relay 42 - - 44 of the first machine which at 142 - - 144 initiates the starting operation and at 67 - - 69 closes a maintaining circuit for the contactor 59 through contact 8 - - 10. This circuit is broken when the controller reaches its next position and the motor is stopped. Should the machine be locked out and contacts 72 - - 74 therefore closed this maintaining circuit will remain closed through contact 11 or 12 and the controller will continue to run and start the next machine. Should the first machine fail to start within a time limit the time delay relay 56 will, through its contacts 58, energize relay 75 which will close a maintaining circuit for itself and energize the contactor 59 to cause the controller to effect the starting of the second machine. Switches 39 - - 41 arc closed when a machine in put in operation and vary accordingly the current in the machine coil of each load-responsive relay. When time delay reverse relay 70 closes contacts 71 the reverse contactor 61 is energized from the control bus-bars. This closes a maintaining circuit for itself over contact 14 of the controller and the controller is run backwardly to the next position de-energizing a starting relay 42 - - 44 in so doing. Should the machine controlled in this position be lucked out contact 12 or 11 of the controller will maintain the circuit, of contactor 61 to cause the controller to continue running to the next position. A switch 39 - - 41 is opened when a machine is closed down. The operation of the first machine in a station may be initiated manually or by remote control and according to the Provisional Specification a switch may be provided to alter the sequence of the machines without shutting down.