Patent GB-232824-A (GB)
Title: Improvements in arrangements for charging and regulating the voltage of secondary batteries
IPC: H02J7/02
Filed: 1924-07-18
Abstract: 232,824. Western Electric Co., Ltd., (Scruby, S. V. C.). July 18, 1924. Systems of charging galvanic batteries; regula tion, automatic. - A secondary battery system applicable to the power plants of small automatic telephone exchanges, comprises means for maintaining a constant voltage across the busbars during discharge by successively eliminating cells of a counter E. M. F. battery, means for starting a motor-generator charging plant when either a predetermined number of counter cells has been eliminated or a certain quantity of energy has been taken from the battery, the charging being continued until both the, voltage of the battery and the quantity of electricity passing thereto reach predetermined values, and means for signalling at a supervisory exchange the failure of certain parts of the apparatus. The main battery 1 and counter battery 2 are connected through an end cell switch B to busbars 3, 4, the positive one being earthed. A voltage relay VR across the bus-bars closes the contact A upon diminution of voltage and energizes a relay R4 which in turn energizes a relay 23 to connect a pilot-motor SM to the bus-bars in such a way that the switch B is rotated counter clockwise to eliminate some of the cells 2. A cam-wheel C rotating with the switch B closes contacts 37. 39 while the switch B is between contacts and thus maintains energization of the relay 23 even though the voltage relay VR may open. When the switch B reaches a position determined by the position of a plug P between one of three contacts S1, S2, or S3 and a sector 43, a relay R1 is energized and in turn energizes a switch AS to complete the circuit of a motor M driving a generator G, which upon attaining a sufficient voltage is connected to the battery by a cut-in switch AC1. In a similar manner, charging is started when the battery has discharged to a predetermined proportion of its capacity by an ampere-hour meter ARM closing its contact X to energize a relay R7 whose contact is in parallel with that of the relay R1. The switch AS also closes a contact 55 to complete a holdingÀon circuit from busbar 4, through parallel connected contacts of relays R2, R3 to earth, charging therefore continues until both relays R2, R3 are operated. As the charging proceeds the voltage across the bus-bars 3, 4 tends to increase and the relav VR closes the contact B to energize a relay R5 which in turn energizes the relay 23 to connect the motor SM for clockwise rotation, the cam-wheel C functioning as before by closing contacts 38, 40. When the switch B reaches a position determined by the position of a plug P1 between one of three contacts T1, T2 or T3 and a corresponding sector, the relay R2 is energized and locks-up over its right-hand winding and back contact of the relay R3. On completion of the charge, the ampere-hour meter AHM closes its contact Y and energizes the relay R3 thereby causing de-energization of relay R2 and of the switch AS with consequent shutting down of the mator generator GM. Contacts 41, 42 and 44, 45 interrupt the circuit of the relay 23 when the switch B arrives at the limits of its travel. An alarm signal ALS at the supervisory exchange operates should any of the contacts 65 of a motor stator relay SR fail to open or should the cut-in switch AC1 fail to operate, the circuit to the signal being completed through a contact 58 of the switch AS. The signal operates also if contacts 63 of a relav R6 in the circuit of the pilot-motor SM fail to open after the relay 23 has been operated, and also as long as either of the relays R4 or R5 are energized, the circuit being completed through contacts 59 or 61. When manual operation is to be substituted for automatic operation, switches K1, K2 are opened, switch K3 is thrown to cut out a compound winding of the generator G and switch K4 is closed.