Circuit arrangement and method for fault locating in conjunction with equipment for the trunk feeding of electrical loads

Claim 1

In a circuit arrangement for fault location in equipment for a trunk supply loop (B) that supplies electrical loads (53 1 . . . 53 n ; 58 1 . . . 58 n ) by means of dc series feeding, said circuit arrangement including supply equipment provided at a supply point which is switchable from a constant current source for feeding said trunk supply loop to a constant voltage source for feeding a test circuit connected to said supply point via a resistor, said resistor being series-connected in said test circuit to a voltage source so that the current flowing in said test circuit (J T ) is oppositely directed relative to the trunk supply current (J F ), said trunk supply loop being free of devices for automatically closing the trunk supply loop ahead of a point of interruption and being fed unilaterally, there being disposed in said trunk supply loop, (1) diodes (54 1 . . . 54 n ; 57 1 . . . 57 n ), connected parallel to said electrical loads, whose polarity is in the blocking direction for the trunk supply current, and (2) cross branches connected across said trunk supply loop, each comprising a series connection of an ohmic resistance (56 1 . . . 56 n ) and a diode (55 1 . . . 55 n ) whose polarity is in the blocking direction for the trunk supply current, the improvement comprising (1) additional cross branch, connected across said supply point at said supply equipment output and containing a diode which conducts current only in the test direction, and (2) a plurality of window discriminators connected across said supply point, there being one window discriminator per cross branch.