Patent GB-217637-A (GB)
Title: Improvements in or connected with the generation, distribution and control of electric power
IPC: B61L3/10
Filed: 1923-03-15
Abstract: 217,637. Maxwell, J. M. Scott-. March 15, 1923. Systems, sectional-conductor. - An electric railway system is divided into separate sections, each having its own electrical-generator unit which is controlled from a train in that section or in the next section behind, or from both sections. A train leaving a section will reduce the output voltage of that section to zero, if another train is following in the next section, or if that section is empty it will stop the generator. The voltage and capacity of the sections may differ to suit the track alignment. A generator A, Fig. 1, is driven by an internal-combustion engine B started by compressed-air or by a motor C and accumulator D. The engine B may be supplied with oil from small reservoirs or a pipe line. The generator is controlled by energizing its field A' by an exciter E having a field E' connected to a control rail F<4> and the accumulator D. The train contact G connects with a driver's control switch H which, when in starting position H', is opened by a spring when the driver releases his hold. In the position H' the automatic starter J is energized and also on step J<2> the shunt coil L<2> of a time relay L. This relay then lifts and opens its contacts L<3>, L', coil L<2> is de-energized on step J<3>, and the relay L drops to close contacts L<3>, L<4>, a dash-pot L<5> giving several minutes delay to enable the engine B to reach full speed and take full load. Contact L<4> energizes a starting-relay M which is maintained at M<1> and connects field E<1> to rail F<4> through the contacts M<2>, N<1> of a safety relay N. Switch H cannot be placed in position H<2> unless the regulator Q<1> has full resistance, but it then excites field E<1> and series coil L'. A stopping- relay P is energized with relay M, but a dashpot P<3> prevents its movement if coil L<1> is energized as soon as the contacts L<3>, L<4> are closed. Coil L<1> is de-energized whenever the train stops, but relay P only acts when the length of stop is abnormal and it then opens starter J and a device U for stopping the engine B by cutting off the fuel supply. The train can be stopped by opening switch H or a circuit-breaker S without stopping the power unit. The power unit is protected by a series relay T operating an overload and a circuit-breaker S<2> operating on short circuit, the breaker. S<2> being restored by hand or bv remote control from the train. To control the unit in the next section, its control rail F<5> is continued into the preceding section, is energized at contacts V<5> by contacts on the vehicle, and then engaged by a contact G<1> connected to switch H and a regulator Q<2> independent of but operated in synchronism with regulator Q'. The control rails F<4>, F<5> overlap sufficiently for the voltage in section 5 to be adjusted to that in section 4. The train is reversed by switches S<4> interlocked with switch H so that switches S<4> will not operate unless switch H is open and the supply voltage is zero. For blocking purposes, each section has at its entering and leaving ends switches X<21> and X<32>, X<31> and X<42> &c., Fig. 2. These switches are mechanically opened by a passing train and are closed by switches Y<2132>, Y<3142> &c. situated at a train's length from the entrance to the corresponding section. The safety relay N of say 3 station is wired in parallel with switches X<31>, X<32> so that if a train in section 3 opens switch X<32>, before switch X<31> is closed at Y<3142> by a train entering section 5, safety relay N and field E' will be de-energized and the power supply stopped, but as soon as Y<3142> is operated to close X<31>, the relay N operates and the train starts automatically. Each station may have more than one generator set in case of failure of one set, but if all fail, the faulty section may be automatically energized from the section on either side. For terminal lines and junctions, the control rails may be operated with the track points and the third rails correspondingly connected. To run two or more trains into the same terminal track, a separate control rail may be supplied for each train, each rail being successively shorter by one train length, and the third rail divided into sections by one train length, only one train having control.