Measuring circuit for monitoring insulation resistances

摘要

Measuring circuit for monitoring the insulation resistances of wires (Aa1, Ab1; Aa2, Ab2; ...; Aan, Abn) to earth which are arranged in various telecommunication cables for measuring purposes and the length L of which is known, with a voltage-fed resistor allocated to each wire and an evaluating device common to all wires, by means of which the starting points of the wires can be connected via controllable switches via a measuring line. The resistor (Ran; Rbn) allocated to one wire (Aan; Abn) is divided into two different resistors (R1n + R3n; R2n + R4n), the free end of the wire (Aan; Abn) being connected to the output of the second part-resistor (R3n; R4n) and the input of the first part- resistor (R1n; R2n) being continuously connected to a supply potential (UB). A tapping point (4; 5) is connected to the line connecting the two resistors. The tapping points of the divided resistors can be connected to the evaluating unit (10) with the aid of switches (6, 16; 6', 16') which can be controlled sequentially in time. <IMAGE>