Patent GB-314531-A (GB)
Title: Improvements relating to regulating systems for dynamoelectric machines
IPC: H02P9/12
Filed: 1929-06-22
Abstract: 314,531. Associated Electrical Industries, Ltd., (Assignees of Bergvall, R. C.). June 29, 1928, [Convention date]. Exciting.-In order to regulate the voltage or other electrical quantity of a dynamo-electric machine, the machine or its exciter has in addition to a main separately excited field winding, an auxiliary separately excited differential winding, and a switching device is provided responsive to changes in the electrical quantity to be regulated arranged to vary abruptly the excitation of the auxiliary winding on the occurrence of abnormal changes in the quantity. As shown in Fig. 1 applied to the voltage regulation of a generator or synchronous condenser 1, the exciter 7 is provided with a main field winding 9 and a differential field winding 11 excited from continuous current mains 21, 22. In the circuits of the windings 9 and 11 are rheostats 12 and 13 coupled together and operated by a pilot motor 19. The rheostats are so arranged that when the contact arm of one is on the operative regulating range, the other is in the position of maximum resistance. The motor 19 is controlled by reversing switches 32 and 33 in dependence upon a regulator 34. The regulator 34 is provided with an actuating coil connected to a voltage transformer 36 across the supply conductors 3, 4, 5. In the de-energized position of the switches 32, 33 shown, the armature 38 of the motor 19 is short-circuited through contacts 45, 46 and leads 39, 41, 44. If the voltage of the machine 1 or the connected mains decreases, the winding 35 of the regulator 34 is less strongly energized and contacts 56, 58 are closed to energize the coil 53. whereby switch 32 moves to the right. The short-circuit across the armature 38 is broken at 45 and the armature is connected across the mains 21, 22 through contacts 46, 47. The pilot motor therefore operates in a direction to decrease the resistance in the circuit of the field coil 9. The movement of the switch 32 also shunts the rheostat 12 through conductors 69, 71 and contacts 67 so that the exciter voltage rises rapidly. Contacts 68 on the switch 32 serve to short-circuit a portion of a resistance 72 in series with the coil 35 of the regulator 34 to hasten the separation of contacts 56, 58, and prevent shunting. When the voltage of the machine 1 approaches its normal value, contacts 56, 58 disengage, switch 32 moves to the left, and the motor 19 stops promptly and re-establishes the short-circuit across its armature. If the movement of the rheostat 12 has been insufficient, the action is repeated. If the voltage of the main machine rises above the required value, the regulator 34 closes the contacts 55, 57, thus energizing the coil 54 and moving the switch 33 to the right. The circuit through the armature winding 38 is closed in the opposite direction so that the motor rotates in a direction to increase the resistance in the field winding 9. Movement of the switch also interrupts at the contacts 73 a shunt to a rheostat 27 to cause a rapid decrease in the excitation of the winding 9, and contacts 74 close a circuit through a resistance 75 shunting the regulator coil 35 to hasten the disengagement of the contacts 55, 57. On completion of the regulation, the pilot motor is braked as before and the action is repeated in the event of incomplete regulation. If the voltage of the supply conductors drops below a predetermined amount, as, for example, on the occurrence of a short circuit on the line, the energization of the regulator winding 35 will be reduced sufficiently to permit engagement ot contacts 60, 61 whereby relays 66, 29 are energized in parallel. The former short-circuits a resistance. 24 in the field circuit 9, and the latter interrupts the circuit of the opposing coil 11 at the contacts 28, whereby the excitation of the exciter rises rapidly. In a modification, Fig. 2, the excitation of the field winding 9 is controlled by a vibrating regulator 86 energized as in the previous example through a voltage transformer 26. The regulator comprises a regulating magnet 87 and a vibrating magnet 88. The electromagnet 87 actuates a lever 91 pivoted at 92 to a bell-crank lever 93 supported on a fixed pivot 94, and the electromagnet 88 is mechanically connected to the horizontal part of the lever 93. When the voltage in the circuit 3, 4, 5 falls, the energization of the magnets 87, 88 decreases causing the levers to move a contact 97 on to a fixed contact 96. A circuit is completed from a continuous current source such as a battery 98 through the winding of a relay 99 and a vibrating or anti-hunting relay 101. The relay 99 short-circuits a resistance 84 in the circuit of the field coil 9, and the contacts of the relay 101 short-circuits part of a resistance 102 in series with the coil of magnet 88. The core of this magnet rises and falls and causes separation and engagement of the contacts 96, 97. A polarized relay 103 connected across the exciter terminals is normally energized so that the armature 106 occupies the position shown, but if the energization of the field winding is reduced to such a low value that the differential winding 11 causes a reversal in the field flux, the armature 106 will move to close the circuit of a relay 108 which short-circuits the field coil 11. A relay such as 103 may be employed in connection with the arrangement shown in Fig. 1. The Specification as open to inspection under Sect. 91 (3) (a) contains a claim for the method of regulation applied to a machine in which the main and auxiliary differential windings are not separately excited. This subject-matter does not appear in the Specification as accepted.