D-C power supplies and isolation of faults on electric transit systems: Part I

THE PROBLEM of obtaining selective tripping of feeder circuit interrupters on d-c traction systems is an old one which has challenged the ingenuity of design engineers for many years. The ideal operating condition is one that keeps the feeder circuit breaker closed under all conditions of normal loads and quickly opens the interrupter when a short circuit occurs on its circuit, all other interrupters remaining closed.