Circuit for measuring loop resistance of a live network - has oscillator feeding coil with conductor as bar primary with pick-up indicating resistance

摘要

A system for measuring the resistance of a closed electrical circuit such as that of a lightning conductor installation. This is achieved having to break the circuit. The system consists of an oscillator (1) which is connected to a coil with a movable magnetic core. The magnetic core acts as a measuring tong (2) which is clamped around the conductor (3) whose resistance has to be measured. There is also a millivolt meter (4) which is linked to a second measuring tong (5). The oscillator feeds an alternating voltage to the coil and this is picked up by the second coil. The reading produced by the second coil will be a function of the resistance of the circuit.