第三軌条方式
Low Voltage propulsion control was coming into style around the time the earliest A/B Standards were being delivered. Therefore, it was no surprise that they arrived with this feature. On earlier high voltage propulsion control systems, 600 volts ran through the motorman's control stand, as well as through the train via the use of jumpers between cars. This had to be the case to make the electrical contacts to allow all of the motor cars of a train to draw power in a synchronized effort from the Third rail. However, this could be dangerous for motormen and shop personnel alike by creating an electrocution hazard. Even unpowered trailer cars had to carry the 600 volts through these jumpers because it was necessary to pass on the voltage to motor cars behind the trailer so as to synchronize them with the lead car. However, Low Voltage propulsion control utilized battery voltage (32 volts) to control the train's motors. This battery voltage was what would pass through the motorman's control stand and between cars. Tractive effort throughout the train was synchronized by the battery voltage in this way. Meanwhile, each car would respond individually to the battery voltage, by moving its own 600 volt contacts to direct power obtained locally by each car directly from the third rail toward the motors. Using 32 volts to control the propulsion in this way was a much safer proposition than the 600 volts associated with the older high voltage setup. This also meant that an A/B Standard crossing onto a dead section of the third rail would not energize it by bridging the gap between it and the previous live section. This was especially beneficial to track workers who had requested the third rail power off in performing their duties. All told, Low Voltage propulsion control tremendously improved safety for train crews, shop crews, and track gangs. However, the conductor had a 600 volt knife switch located inside his control panel to activate the ventilation system and other accessories.