Patent GB-674873-A (GB)
Title: Improvements relating to methods of and apparatus for measuring consistency
IPC: G01N11/14
Filed: 1949-02-09
Abstract: 674,873. Electric measurements. PATTERSON CO., C. J. Feb. 9, 1949 [Oct. 28, 1948], No 3590/49. Class 37. [Also in Group XIX] In order to indicate relative viscosity of a batch of dough or like material from the power input to the mixer, a recording device continuously measures the difference between peaks of input power represented by the distances a, b in Fig. 1, and c, d, e in Fig. 1a, and records them in the form of a curve f shown in Fig. 2. The curve f obtained from a standard batch may then be used as a reference for comparison with other curves g, h, j, representing non- standard batches in order to ascertain the necessary corrective steps to bring these batches to the standard consistency. Current and voltage transformers 26, 28, respectively, in the supply line 20 of the mixer motor 22, feed the electronic wattmeter comprising a pair of cathode-coupled triodes 32, 34 with power input data. The output of the electronic wattmeter, if recorded, would produce a power curve of the type shown in Fig. 1. Measurement of the components c, d, e, shown in Fig. 1a, is effected by a voltage-doubling peak rectifier comprising a pair of oppositelydisposed diodes 50, 52. The output from the diodes is then fed to a differential voltmeter comprising a second pair of cathode-coupled triodes 54; 56, with a balancing potentiometer in the anode load circuit. The output from the differential voltmeter is taken via leads 60, 62, to a recording milliameter upon which the curves shown in Fig. 2 are produced. In an alternative arrangement shown in Fig. 4, the instantaneous measurement of power is taken from one peak to the mean power level represented by the measurement k in Fig. 1a. The circuit is similar to that of Fig. 3 with the exception of the peak rectifier circuit comprised by the diodes 112, 113. In this arrangement the diode 112, resistance 114 and condenser 116, with diode 113 added to balance out contact potential, produce a potential proportional to the peak power envelope, whilst the average power reference level is produced by filtering out the peaks by a filter network, comprising resistances 120, 122, 124 and condensers 126, 128 thus producing a potential proportional to the average power level shown in Fig. 1a. The two potentials are passed to a differential electronic voltmeter comprised by the triodes 132, 134, the output of which is fed to a recording milliameter 136 as before. A relay 76 in Fig. 3 and 140 in Fig. 4 operates the motor associated with the recording milliameter, the switch 142 being operated by a cam in this motor, 138 in Fig. 4, to ensure that a complete minute space is traversed by the recording pen before the motor is stopped after power to the mixer motor has been switched off. Voltage regulator valves 70, 72 in Fig. 3 and 150, 160 in Fig. 4 are provided to eliminate the effects of supply voltage variations in known manner, the heaters or filaments of the valves being connected in parallel, in pairs, as. shown diagrammatically in Fig. 3 at 32a, 50a, and 54a, for the same purpose. A phase adjuster 46 in Fig. 3 and 110 in Fig. 4 is also included in the electronic wattmeter section.