ANORDNING FOR STROMFORSORJNING AV ETT ANTAL FUNKTIONSENHETER FORDELADE LENGS EN TRANSMISSIONSLEDNING

摘要

A power supply system for a number of functional units distributed along a transmission in which each unit gets its supply from a constant voltage circuit connected across the transmission line. Each unit may have a low power and a high power state. The power supply which is located at one end of the transmission line is a constant voltage supply with current limiting features. The constant voltage circuits each comprises a Zener diode connected in series with an adjustable constant current circuit and a system for setting the constant current circuit on either the low or the high power state. When the high power state is set, the voltage across the constant current circuit is sensed and if this voltage is too high, the constant current is further increased until the current limiting of the power supply operates thereby decreasing the voltage across the constant current circuit to a safe value.