Patent GB-210433-A (GB)
Title: Improvements in or relating to electric power and distribution systems
IPC: H02J3/42
Filed: 1924-01-23
Abstract: 210,433. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Wensley, R. J.). Jan. 23, 1923, [Convention date]. Equalizing load on generator; systems depending on the use of two or more machines. - A supply system is provided with a subsidiary power station adapted to be started in response to a distant control apparatus, to a float switch controlled bv the head of water available in a hydro-electric system, or to a frequency relay controlled by the frequency of the system. The prime-mover is started and accelerated until the subsidiary generator is in synchronism with the main generator and the subsidiary generator is connected automatically to the line when synchronism is attained. Upon the occurrence of a heavy short-circuit or failure of the main generator the subsidiary generator is connected up without waiting for the synchronizing apparatus to function. In the event of a short-circuit the subsidiary generator is connected up and disconnected a predetermined number of times and finally remains disconnected unless the shortcircuit is removed. A supply system 1, which normally receives power from a main generator 2, is adapted to receive additional or alternative power from a generator 3 actuated by a water-wheel 4. The starting and switching in of the generator 3 is initiated by a relay 5 energized from a battery 6 by the closure of a float switch 7 or a frequency relay 8, or a selector relay 9, or relay 10, or an additional relay 12 if the control system 11 fails. The operation of the relay 5 closes the switches 14, 15 and opens the switch 16. The switch 14 closes a holding circuit for the relay 5, and the switch 15 closes the circuit of a solenoid 17 which operates a valve controlling the admission of oil to a control mechanism 18 associated with the governor 19 of the water-wheel 4. As the generator 3 and an exciter 20 therefor are accelerated, the voltage of the generator gradually increases and finally a voltage relay 21 closes two switches 23 and 24. The switch 23 connects the coil 25 of a synchronizing device 26 to the generator 3 through a transformer 22 and the switch 24 connects a second coil 27 of the synchronizing device to the supply mains 1 through a transformer 28. The switches 23 and 24 also connect synchronous motors 30, 31 to the generator 3 and supply line 1 respectively. The motors 30, 31 operates a switch contact 33 through differential mechanism 32 in such a manner that the contact 33 engages a contact 34 when the feed of the motor 30 exceeds that of the motor 31, and the contact 33 engages a contact 35 when the speed of the motor 30 is less than that of the motor 31. When the speed of the generator 3 is less than that of the mains 1 the closure of the contacts 33, 35 energizes a relay 36, thereby closing the circuit of a reversible motor 39 through a limit switch 40. The motor 39 controls the governor mechanism to increase the speed of the generator 3. Similarly, if the speed of the generator be greater than that of the mains 1 the closure of the contacts 33, 34 energizes a relay 37, thereby closing the circuit of the motor 39 through a limit switch 43, and the motor 39 controls the governor mechanism to decrease the speed of the generator 3. When the generators 2 and 3 are in synchronism the device 26 closes the circuit of a relay 46 at the switch 45. The relav 46 completes at the switch 49 the circuit of the closing coil 47 of the interrupter 48 which is latched in its closed position. The interrupter 48 is associated with a pluralitv of switches 50, 51, 52 and 53 which are opened when the interrupter 48 is closed, and a plurality of switches 54, 55, 56, 57 and 58 which are closed when the interrupter 48 is closed. The opening of the switch 50 disconnects the synchronizing device 26 and the motors 30, 31 from their operating circuits by deenergizing the relay 21. The closure of the switch 54 energizes a cut-off relay 59 which operates to break the circuit of the relay 46. The opening of the synchronizing switch de-energizes the relay 59. After the generator 3 is connected up, the governor 19 is adjusted to maintain a predetermined speed of the generator by means of a relay 61 the switch 62 of which is connected in parallel with the switch 51. A holding circuit for the relay 61 is closed over the limit switch 40. The closure of the switch 62 of the relay 61 completes the circuit of the relav 36 over the switch 58 and the motor 39 is operated to adjust the governor to the limit at which the switch 40 is set. The opening of the switch 40 de-energizes the relay 61 and consequently the relay 36 so that the governor is now removed from the controlling devices until the interrupter 48 is opened. Upon the occurrence of a heavy short-circuit or the failure of the generator 2 the generator 3 is connected up without waiting for the synchronizing apparatus to function. Under this condition a voltage relay 87 operates to complete the circuit of a reversible motor 67 over the contacts 70, 71 of a switch 65 and the switch 53 across the exciter 20. The switch 65 is operated by the motor 67 to energize the re-setting coil 84 of relay 66 over the segment 78 and the switch 82 if this be closed, thereby closing the switch 81. The motor 67 continues to operate the switch 65 until the segment 75 engages the contacts 72, 73 whereupon the closing relay 46 is energized over the switch 81 of the relay 66 and the contacts of relay 59. If the failure of the line voltage be due to a heavy shortcircuit an overload relay 90 operates to shortcircuit the initiating relay 5. thereby opening the switches 14 and 15 and closing the switch 16 through which and the switch 57 the trip coil 91 is energized to open the interrupter 48. The interrupter 48 is closed on two subsequent occasions if necessary by the further operation of the motor 67 and the engagement of the contacts 72, 73 by the segments 76, 77. If after re-closure of the interrupter 48 the fault be cleared. the switch 65 is returned to its initial position.