| 摘要 |
884,869. Automatic control systems. SUL. ZER FRERES S.A. Feb. 26, 1960 [March 5, 1959], No. 6873/60. Class 38 (4). [Also in Group XXIX] In a signal transmission system only the maximum or minimum signal of a number of signals is normally transmitted but the next signal in order of magnitude is transmitted when the maximum or minimum signal is outside a limiting value. In a steam generator, for example, a number of thermocouples or resistance thermometers may produce electrical signal voltages representative of the temperature at different points of the tubes of a superheater surface. In Fig. 1 such signal voltage U 1 -U 4 are applied through rectifiers 14, which may be of the semi-conductor type, so that a common line 15 is at a voltage corresponding to the highest of the signal voltages, since only the rectifier associated with that voltage will be conductive. The consequent current through this rectifier operates its associated relay 13 so that the highest signal voltage is disconnected from a second common line 17 to which the remaining signal voltages are connected through rectifiers 16 so that line 17 is at a voltage corresponding to the second highest signal voltage. The highest signal voltage is normally transmitted from line 15 through contacts of a relay 18 to a device 12, which may operate to regulate the superheater temperature automatically, e.g. by controlling water injection, but, should the difference between the highest and next highest signal voltages exceed a predetermined value, indicating that the highest signal voltage is the result of a fault in the detector, relay 18 operates to substitute the next highest signal voltage from line 17 to control device 12. In modifications changeover is effected if the difference between the highest signal voltage and the mean of some or all of the signal voltages exceeds a predetermined value, or if the absolute value or rate of change of the highest signal voltage exceeds a predetermined value. The voltages on the common lines may be maintained above a minimum value by a voltage applied through rectifiers. More than one high signal voltage may be rejected. An arrangement involving only fluid-pressure signals with means to ensure smooth changeover is described (see Group XXIX). Applications to the control of temperature of the fuel elements of a nuclear reactor and to the control of pressure are referred to. |
