A Control system for Modern Multiple- Unit Rapid-Transit Cars

Operating the series motors of a street railway car as series generators is a convenient way of providing electric braking, but, since thle motors are self-excited while braking, they are very sensitive to changing speed and load conditions. This is particularly true of modern small highspeed motors which operate at relatively low-flux densities. Control systems are available and in use, however, which provide a smooth, responsive and flexible electric brake which has replaced the air brake as the pricipal means of braking modern cars in street railway service. The use of such a control system with electric braking has been extended to multiple-unit rapid-transit cars by adapting the equipment of the PCC car to conform to the requirements of remote control without sacrifice in safety or reliability, and by providing special features in recognition of the distinctive operating conditions encountered in rapid-transit service.