Patent GB-250627-A (GB)
Title: Improvements in and connected with electrical installations for railway and like vehicles
IPC: H02J3/14
Filed: 1924-11-18
Abstract: 250,627. Stone & Co., Ltd., J., and Kennard, A. E. Nov. 18, 1924. Controlling lighting and heating systems; regulation, automatic. - In systems ior railway and like vehicles the dynamo is adapted to produce a voltage above that required for the normal circuits which it supplies, and automatic means cut in, progressively and in series with the normal load, auxiliary consumption devices which absorb the excess voltage. These means may be a governor actuated switch, a voltage solenoid or solenoids, a motor driven regulator, or a voltage and current solenoid or a governor or solenoid may control a relay motor. They may act directly, or indirectly (over contacts controlling contactors) and may be combined with the usual cut-in switch. This last may be an automatic reversing switch. The automatic means may also cut in field resistance progressively or in such a way as to limit voltage at high speed. The dynamo may be automatically controlled for constant excitation and constant current output or separate battery excitation may be used; it may commence to generate under self-excitation and subsequently its field may be connected to the battery and later disconnected from the generator. Two dynamos may be used in parallel or in series. The auxiliary devices which absorb the excess voltage may be heaters or cooking elements, additional lighting circuits, fans or other power load, or battery cells, e.g. ferro-nickel, supplying independent circuits. This battery may be interchanged automatically with the main battery and arrangements for switching in its cells alternately from opposite ends of the battery may be provided. Where resistance heaters are used the last two or three of such may have very high resistance to protect the installation. The normal circuits may comprise a complete two-battery system of known type. The automatic arrangements may be connected up to control more than one generator. Fig. 1 shows an automatic reversing cut-in switch as described in Specification 7468/10 arranged to operate by its centrifugally controlled disc g<2> a switch f to cut heating units H<1> H<5> into series with the normal circuits comprising battery B and cookers C. As shown in Fig. 2 the rising voltage of the generator successively opens switches S<1> - - S<7> short circuiting heaters H' - - H' in series with cookers C through relays R<1> - - R'. The dynamo field and the switch coils are connected as shown so that the currents in these circuits are restricted by the resistance of the heaters cut in. In Fig. 3 a solenoid S balanced against a spring l<1> causes a motor M to move a switch arm f to cut in or out heaters H according as the dynamo volts rise or fall. The solenoid S<1>, motor field M<1>, and cookers C are connected in parallel between the negative main lead and the battery terminal on the dynamo D. This arrangement may be modified by using two solenoids and a double ratchet and pawl in place of the motor M. Fig. 4 shows a rectilinear slider actuated by a motor M<2> with a series connected armature against a spring t to insert heaters H as the dynamo volts rise above the battery voltage. A cell switch for a battery which is to be inserted in steps as a series load is shown in Fig. 7. The cells being switched in from opposite ends of the battery at alternate periods of use. A motor M drives an arm f carrying two contacts in the main circuit over two series of contacts f<1> - - f<8> connected as shown and is arranged so as to move the arm away from its central position as the dynamo volts rise and vice versa. Each time the arm reaches the central position it operates a switch 9 to reverse the motor so that the succeeding operation takes place over the opposite series of contacts.