GB1209402A - Improvements in or relating to electrical indicating and monitoring apparatus - Google Patents

Abstract

1,209,402. Automatic control. HONEYWELL Inc. March 12, 1968, No. 12023/68. Heading G3R. Anelectrical indicator is associated with switching means and differential circuits to indicate (a) the value of a controlled variable (b) a pre-set reference value and (c) when a second reference valve is adjusted to be equal to a first. In Fig. 1, a voltage dependent on the magnitude of a process variable is applied at 12 and compared by a differential amplifier 14 with a voltage from a potentiometer 36 set to correspond with a desired value of the variable. Any difference, representing an error, is effective, through a control amplifier 16 and a controller 18, to restore the variable to its desired value automatically. If the process variable deviates beyond upper and lower limits determined by the settings of potentiometers 44, 55, differential transistor or valve amplifiers 46, 60 cause relay operation of alarms such as 53. Additional relay contacts (not shown) controlling the transistor amplifiers ensure positive operation of the relays. A meter 20 has a scale which is adjusted relative to a fixed index by potentiometer 36 so as to indicate the desired value. The meter pointer is moved relative to the fixed index by the output of amplifier 14 to indicate the deviation. The indication of the pointer relative to the scale thus indicates the magnitude of the process variable. Operation of switches 24, 26 to their other position permits manual control of the process variable by a potentiometer 31 operating through amplifier 16. A condenser 28, charged during automatic control, and a condenser 22, charged during manual control, ensure smooth changeover. With switches 24, 26 set for manual control, the upper and lower limits for the process variable may each be indicated on meter 20 by adjusting potentiometer 36 and then operating the appropriate switch 40 or 42 so that potentiometer 44 or 55 may be set to its correct position at which the deviation indicated by meter 20 will be zero. The alarms may alternatively be operated by excessive output from amplifier 14, and the signal dependent on the process variable may be utilized when setting the limits. A suitable construction of indicator combined with control switches and potentiometers is described. 1,209,415.Fluidic pulse converters. HONEYWELL Inc. Feb. 21, 1969 [Feb. 23, 1968], No. 9488/69. Heading G3H. A pure fluid pulse converter comprises an amplifier 11 fed through a duct 20 with a pulsating input signal which is transmitted to control orifices 16, 15 by a short line 21 and a longer delay line 25 provided with a trombone slide 28 which is adjusted automatically in response to temperature variations sensed by a helical bi-metal element 30 in the path of the working fluid. Output limbs 13, 14 feed capacitances 35, 37 through resistors 36, 38 so that the difference in pressures in conduits 39, 40 varies as the frequency of the pulses applied to duct 20. As shown the amplifier is mono-stable with a preferred outlet 13, but in various modifications (not shown) abi-stable amplifier can be used, or the capacitances 35, 37, omitted so that the device forms a pulse shaper. The signal fed to duct 20 may be derived from a temperature responsive fluid oscillator (not shown) in the working fluid of a gas turbine.