Patent GB-190828190-A (GB)
Title: Improvements in Electric Voltage Regulators.
Inventor: TIRRILL ALLEN AUGUSTUS
Filed: 1908-12-24
Granted: 1909-09-23
Abstract: 28,190. Tirrill, A. A. April 27, [date applied for under Section 91 of Patents &c. Act, 1907]. Regulating; switches.-The relay of a voltage-regulator is provided with a number of cores energized by a single winding consisting of two permanently closed coils and two coils energized by the closing of another relay. The cores of the first relay operate armatures which short-circuit resistances in the field circuits of the exciters of the main generators. Resistances 11, 12, 13, Fig. 4, placed in series with the fields of the shunt-wound exciters 8, 9, 10 of the generators 3, 4, are short-circuited by closing the contacts 15, 19, 20, 22 by means of a relay having coils 27,28,29,30. The voltage relay of the regulator consists of two pivoted levers 54, 58 connected to movable cores 52, 57 and carrying contacts 55, 60 respectively. The core 52 is energized by a coil 48 connected in series with a resistance 49 across the leads 7 and surrounded by an iron band 50 ; the core 57 has a potential coil 61 and an adjustable compensating- coil 63. The core 57 is provided with a dash-pot 66, the piston 69 of which is connected adjustably to the core 57, while the cylinder has a by-pass 68 having an adjustable valve 70, Fig. 1. The coils 27, 28 of the second relay of the regulator are permanently connected across the leads 7 by a lead 44, resistance 45, and a lead 46, and the coils 29, 30 are intermittently connected to the leads 7 by the lead 44, resistance 45, lead 47, lever 58, contacts 55, 60, lever 54, and leads 47, 46. The coils 27, 28, 29, 30 are arranged so that the current in the coil 27 flows in the opposite direction to that in the coil 28, while the current in the coil 29 flows in the opposite direction to that in the coil 30. The coils are mounted between the legs of E-shaped cores 31, the arrangement of the windings being such that the inner and outer poles are of the same polarity and opposite to that of the middle poles. The armatures 32 are pivoted to brackets 33 and have arms 34 connected to adjustable springs 35, and their outer ends carry contacts 15, which engage with similar contacts on springs 38 adjustably secured to standards 39. To set the regulator, the rheostats are adjusted to a point that will reduce the voltage of the circuit to be regulated considerably below the normal. The.contacts 55, 60 then engage with one another, so that, when the switches 71 are closed, the resistances 11, 12, 13 are short-circuited and the voltage of the exciters and generators immediately rises. When the voltage rises to a predetermined amount, the contacts 55, 60 opon, thereby de-energizing the coils 29, 30 and opening the short-circuit around the resistances, which tends to lower the voltage again. Both relays then continue to operate at a high speed, with the result that a constant voltage is maintained irrespective of variations in the load on the system. 28,192. Allgemeine Elektricitõts-Ges. Dec. 28, 1907, [date applied for under Section 91 of Patents &c. Act, 1907]. Motor control systems.-Consists in a modification of the method of starting rotary-field motors described in Specification No. 22,870, A.D. 1907. According to the present invention, at starting, the centre point of the transformer is left open, as shown in Fig. 3, and the motor is connected about half-way along the windings, which act as choking- coils and supply the stationary motor with about normal current at about one-eighth of. the line pressure. The neutral point N is then closed, Fig. 2, and the motor speeds up with about four times the normal current at half the line pressure. The neutral leads are then opened, Fig. 3, the motor continuing to speed up, and the current and pressure respectively reaching about one-quarter and three-quarters of their normal values. Lastly, the transformer is short-circuited, Fig. 4, giving the normal running-conditions. The motor terminal pressure is thus increased continually by steps without any interruption of the current, as in the method described in the above-mentioned Specification.