Patent GB-196971-A (GB)
Title: New or improved means for effecting phase adjustment of electrical systems
IPC: H04L7/00
Filed: 1922-01-04
Abstract: 196,971. Pernot, F. E., and Rich, L. J. Jan. 4, 1922. Regulation, automatic systems and apparatus for.-In an arrangement for maintaining synchronism or definite predetermined phase relationship between two or more alternating current systems, the output of the controlled alternator is connected through a phasecorrecting device which functions to maintain the required relationship. Signalling may be effected by short interruptions of the controlling current used to control the phase. An alternator 7 supplies current to leads 1, a second alte.rnator 39 driven by a motor 40 supplies current to leads 2, synchronism and definite phase relationship being required between the currents in 1, 2 which may be used, for example, to drive respectively motors actuating telegraphic transmitting-apparatus 5 and receiving-apparatus 5<1> connected to cable 3. Alternating current is taken from leads 1 through transformer 9 and passed through cable 3, amplifiers 12 and transformer 14 to the moving coil 16 of a galvanometer. Current from the generator 39 is supplied to leads 2 through a phase-shifting transformer 37, 38. Alternating current is taken from leads 2, either direct or through an adjustable phase-shifting device 20, 21 to the field-coils 18 of the galvanometer. The device 20, 21 allows adjustment of the required phase-relation which is to be automatically maintained. So long as the required relationship exists, a light contact 23 carried by coil 16 is out of engagement with contacts 26, 26<1> but variation from this relationship results in energization of one or other of the relays 28, 28<1> the contacts of which close circuits controlling a reversing clutch 33 whereby a continuously-running motor 34 rotates, through worm gear 36, member 37 of the phase-shifting transformer in the direction necessary to restore the predetermined conditions. Gear 36 may also operate the arm of a rheostat 43 in the field circuit of motor 40 so that, where a difference of speed exists which would require repeated phasecorrection in the same direction, the effect on the field circuit is cumulative and ultimately adjusts the speed of motor 40 so that further phasecorrection on this account is eliminated. Instead of the phase-shifting transformer 37, 38, the stator of the alternator 39 may be rotatably adjustable, or alternatively, the alternator may be driven through differential gearing, the phaseadjustment being effected by rotating the ring carrying the idler pinions. Any prime-mover may be used in place of a motor 40, the rheostat 43 being replaced by a suitable speed governing device. A phase-adjuster similar to 20, 21 may be placed between the leads 2 and any machine driven synchronously therefrom, so that a plurality of synchronously-driven machines may be separately adjusted in phase. The clutch 33 may be omitted, the gear 36 being directly driven from the motor 34 which is then started and stopped under control of relays. Motor 34 may be driven separately, or from the alternator 39, or mav be dispensed with, the shaft 34<1> being then driven by mechanical connection to the motor and alternator system 39, 40.