Patent GB-266452-A (GB)
Title: Improvements in electric lighting and power plants
IPC: H02J7/34
Filed: 1925-11-25
Abstract: 266,452. Austin Lighting Co., Ltd., and Walker, C. B. Nov. 25, 1925. Charging and discharging batteries; regulation, automatic; supplying consuming devices; starting prime-movers.-An electric generating plant comprises a prime mover B clutched electromagnetically to an alternator A and coupled exciter D. A battery E, charged by the exciter, may supply energy to the alternating current mains through the exciter running as a motor, the prime mover being idle and un-clutched. Governor-controlled speed-regulating means F operating on the shunt field of the exciter maintain constant the speed of the set at such .times. The alternator volts are maintained or compounded at all times by automatic means 35, 38 operating on its field circuit. The engine is started at a given load or battery voltage by automatic energization of the clutch C and is automatically shut down when the load is reduced, provided that the battery voltage is not too low. Overcharge of the battery is prevented by a voltage relay 39 which varies the operation of a solenoid regulator L controlling the exciter field when the engine is running. The field regulators H, J are operated by fluid pressure servomotors and the control of the field of the exciter when motoring is automatically changed over from the solenoid regulator to the governor F when the clutch C is de-energized. On light loads with adequate battery volts the mains 1 ara supplied by the plant E, D, A, the speed of D being kept constant by F and the voltage of A being regulated by a voltage solenoid 35 and a current solenoid 38. The series connected secondaries of current transformers 2 feed the anode circuit of a rectifier 4 which includes the heating coil of a thermal switch 5. At a given load the switch 5 makes contact at 7, armature 13 is lifted and latched and through contact 15 a motor 16 is caused to operate a switch 17. This energizes the clutch which starts the prime mover B and, on reaching contact 19, opens a fuel valve 20 and operates a valve 27 to change the exciter field -control over to the regulator L. This regulator comprises a coil 25 carrying the battery current, a coil 24 energized proportionally to the current in the load circuit and a coil 42 which is switched on by the voltage relay 39 to prevent overcharging. When the load in the mains falls to a certain value the switch 5 leaves contact 7 and makes contact at 8. The prime mover B may be started by low battery volts independently of the load by a thermal switch 9 the heating coil of which is across the battery. At low volts it engages contact 11 the armature 13 is lifted. When the battery is charged this switch makes contact at 10 which is in series with a release magnet 21 and contact 8 of the switch 5. Thus at low load with adequate battery volts the armature 13 is released and contact made at 23 to run the motor 16 in a direction to out off fuel supply, restore governor F to effectiveness and de-energize the clutch C. The voltage relay 39 controls a switch 47 which short circuits contact 10 when the overcharge preventing device is in operation so that resulting reduction in voltage shall not preclude the shutting down of the prime mover which would otherwise result through contact at 10 not being made.