Patent GB-628124-A (GB)
Title: Recording apparatus for electrical measurement
IPC: G01R17/04
Filed: 1946-08-21
Abstract: 628,124. Voltage and current measurements. ROUMEFORT, F. DE S. DE. Aug. 21, 1946, No. 24977. Convention date, May 15, 1943. [Class 37] [Also in Groups XIX and XXXVIII] Fig. 1 shows a recording device for electrical measurements in which a motor M drives a carriage B across moving recording paper with a reciprocating, movement through worm gearing. Reversing switches K are operated at each extremity of the movement of the carriage which bears an electromagneticallyoperated stylus D and moves the slider E of a resistance F which is variable in value according to the carriage position. The resistance is connected in circuit with the quantity to be measured, at terminals 1, and the measuring instrument, whose pointer A normally rests against contact 3, energizing a relay G which completes the motor circuit for reciprocating the carriage. During this reciprocation the resistance F momentarily assumes a balancing value such that the pointer momentarily leaves contact 3 and engages insulated contact 3a. Relay G is then released, breaking the motor circuit and energizing electromagnet H, which actuates the stylus D to make a mark on the paper, the lateral position of which is dependent on the instantaneous magnitude of the electrical quantity being measured. When the mark is made, the electromagnet H operates (for instance through a further relay) to break its own circuit and to re-start the motor. The carriage recommences its movement and the pointer A is restored to its position on contact 3 until a new balance position is reached, at which another mark is made corresponding to the new instantaneous value of the electrical quantity, the variations of which are thus traced as a graph by successive marks. The meter input may be shunted for heavy current measurements, and resistance F may be replaced by a variable inductance or capacity for A.C. operation (Fig. 2, not shown), while contacts. 3, 3b symmetrically disposed with regard to the balance position of the pointer may be connected to release the stylus and traverse control relay when the pointer is momentarily passing through balance (Fig. 3, not shown). Fig. 4 shows a modification in which three separate instruments measuring different electrical quantities at terminals 1, 2, 3 have pointers A1, A2, A3 moving between separate pairs of contacts which are associated with the appropriate relays G1, G2, or G3 controlling the carriage traverse motor circuit and the stylus operating electromagnet. The carriage has three sliders which move over separate variable resistances F1, F2, F3, each being connected in series with the appropriate measuring circuit. Three separate electrical variables can thus be recorded together, the mode of operation being sequential and similar to that of Fig. 1. In a further modification (Fig. 5, not shown), the indications of three separate measuring instruments are recorded by a single stylus under the control of three separate pairs of relays. The passing of an instrument pointer through its equilibrium position operates the appropriate relay to stop the traversing motor and cause the stylus to mark the paper. At the same time the appropriate auxiliary relay operates to re-start the motor independently of the pointer position, the relay being maintained in the operated position until the holding circuit is broken at the end of the traverse, and the instrument is ready to record a further reading. In a further modification (Fig. 6, not shown), means are provided whereby a three-colour inked ribbon is used to mark the paper, the appropriate colour being brought under the stylus when the corresponding unknown is being measured, so that the three records are taken in three different colours. A measured electrical value may be integrated as a function of time by apparatus in which the traverse motor drives a revolution counter (Fig. 8, not shown).