DC line overvoltage limiter cct. - has non-lieear series resistor in each long or shunt branch reacting to temp. variations

摘要

The overvoltage limiter circuit consists of a voltage arrester(s) coupled, across the load and a positive temperature coefficient resistor coupled between the D.C. supply and the load. When the voltage arrester breaks down, heat is developed in it. The resistor responds to the temperature variations, as it lies in thermal contact with the arrester, so that the resistor resistive value increases to a level that reduces the overvoltage to below the arrester breakdown voltage. After the positive temperature coefficient resistor has cooled down, the load is again supplied with full power. This configuration allows voltage arresters of low breakdown voltages to be used.