Patent GB-373350-A (GB)
Title: Control of elastic fluid turbine driven electric power generating plant
IPC: H02P1/16
Filed: 1931-04-14
Abstract: 373,350. Turbine plant. ENGLISH ELECTRIC CO., Ltd., 28, Kingsway, London, LAW, A. H., Stanford House, Stanford, near Rugby, and CHITTENDEN, J. P., South Lodge, Westfield, Rugby. April 14, 1931, No. 11004. [Class 110 (iii).] In a turbo-generator plant comprising compound high and low pressure turbines driving generators which are thrown into or out of operation according to the load demand, the process of starting up a unit is controlled by a remote master-controller and by a switchboard controller in such a way that the starting up of the auxiliary machinery, and the opening of the H.P. and interstage valves is carried out in definite sequence. The Figure shows a layout adapted to start up a compound unit the main stop valves of which have been tripped on the previous stoppage. The master-control panel MC is provided with an arm H adapted, in its rotation, to make contacts at points 1 .. 8 successively, and with reversible rheostats 92, 124, arranged to control, under certain conditions, the motors which actuate the H.P. and L.P. valves. On the switchboard, reversible rheostats 104, 135 are provided for controlling H.P. and L.P. respectively after the unit has been put on load. The circuits of the solenoids, relays, and auxiliary motors are interlocked so that operations must follow one another in a definite order. On the completion of one operation, a circuit for the next operation is prepared. Holding circuits and limiting switches are provided where necessary and lamp signals are arranged to indicate the completion of each operation. Actuating current is supplied by a main 10. In the arrangement shown, the sequence of operations, resulting from the deliberate movement of the arm H over the contacts 1 .. 8 of the master-controller MC is as follows :- (1) When on contacts 1, 1<1>, 1<11>.-(a) The trip gears of the H.P. and L.P. stop valves are reset by solenoids 12, 13, and switches R, Y, which had been actuated on the previous closing down to open all circuits, are reset to enable the controller to function. (b) The condensate pump is flooded, its byepass valves being actuated by a motor 1v. (c) The auxiliary oil pump motor 1g is started up. (d) The main water circulating valve is opened by a solenoid 1s. (2) When on contact 2, a number of governorcontrolled motors driving auxiliary machines are started up in sequence. Three such motors are shown, viz. : 2h for the water-circulating pump ; 2h<1> for the extraction pump ; and 2h<11> for the alternator fans. (3) When on contact 3, a relay brings into action solenoids 3g, 3l, 3m, which open in turn the circulating water regulating valve, the condenser vacuum ejector steam valve, and the circulating water valves to the air and oil coolers. A reversible motor 3t then comes into operation to set the speed adjusting gear of the governor so that the H.P. engine may be run up into synchronism. The next step is to close the interstage valve, which operates in conjunction with the atmospheric relief valve as described in Specification 365,509, unless this valve had been closed by tripping on the previous stoppage. This is effected by a reversible valve-operating motor 3aa, the limit switches of which are actuated by the movement of the nut on the valve stem. The closing of the interstage valve actuates a switch W which prepares a circuit for the operation of the H.P. stop valve by a reversible motor 3bb. (4) When on contact 4, a circuit is prepared which permits the manual control, by a reversible rheostat 92 at the master-control station, of the main valve operating motor 3bb. When the H.P. turbine has been run up to speed, as determined by the preliminary governor setting the motor 3bb is cut out and the governor takes over control. The circuit for the next operation, by which the H.P. turbine, at present running light, is put on load, is prepared by a speed-responsive switch TH and a switch VS which is closed when the main stop valve is fully open. (5) When on contact 5, the switchboard operator is enabled to put the H.P. turbine on load, and when this is done by closing the main circuit-breaker, an auxiliary contact U is closed to make a circuit which enables the switchboard operator to control the governor setting motor 3t by means of the rheostat 104. Reverse movement of the master-control switch over the contacts 5 .. 1 will be ineffective. (6) When on contact 6, the master controller is able to take over control, by means of the reversible rheostat 124, of the motor 3aa which opens the interstage valve of the L.P. turbine. When this is run up to speed, but not under load, a speed-responsive switch TL prepares a circuit for the next operation. (7) When on contact 7, the switchboard operator may take over control, by means of the reversible rheostat 135, of the L.P. turbine, but the main controller may resume control by taking the arm H back to contact 6. When the switchboard operator puts the L.P. turbine on load by closing the contact-breaker, an auxiliary contact V prepares a circuit for the next operation. (8) When on contact 8, the control of the L.P. turbine, which is not governed, is taken back by the main controller from the switchboard operator, and the motor 1v, which actuates the condensate pump valves, is reversed to set the flow in this pump for normal running. When the main valves are tripped for closing down, all control circuits are opened.